Drug Allergies: Diagnosis, Treatment & Prevention (Recording)

This webinar was recorded on October 8, 2025

Drug allergies pose significant challenges in clinical practice, often complicating treatment decisions and limiting therapeutic options. This webinar will provide a comprehensive review of best practices for the diagnosis and risk stratification of suspected drug hypersensitivity, with an emphasis on when and how to apply diagnostic testing. Evidence-based strategies for the management of acute reactions and long-term care will be discussed, along with practical approaches to prevention and patient counseling. Attendees will gain clinically relevant tools to improve diagnostic accuracy, minimize unnecessary drug avoidance, and optimize patient safety in everyday practice.

Speaker:

Mariana Castells, M.D., Ph.D.

Mariana Castells, M.D., Ph.D., is a clinician-scientist with over 30 years of experience in allergy and immunology and over 200 publications. She is the Director of the Brigham and Women’s Hospital Mastocytosis Center, one of the few nationally and internationally recognized centers of excellence, which provides diagnosis, management, and treatment options for patients with mastocytosis and mast cell activation disorders. She is actively involved in mast cell-related research and is the PI on several clinical trials, including Blueprint, Cogent, and Thelios. She is also the Director of the Drug Hypersensitivity and Desensitization Center at Brigham and Women’s Hospital and the Dana Farber Cancer Institute. This center has provided over 900 high-risk desensitization per year for over 20 years to patients with cancer and chronic inflammatory diseases. Dr. Castells is also a Professor of Medicine at Harvard Medical School and Editor in Chief of Current Allergy and Asthma Reports.

This Advances webinar is in partnership with the American College of Allergy, Asthma, & Immunology. ACAAI offers CMEs for physicians for this webinar. If you are a member of ACAAI, you can obtain CME through the member portal for the Advances webinars.

All attendees will be offered a certificate of attendance. No other continuing education credit is provided.

CME is available through ACAAI for this webinar.

Sponsored by the American College of Allergy, Asthma and Immunology

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Transcript: While this transcript is believed to be accurate, errors sometimes occur. It remains your responsibility to evaluate the accuracy and completeness of the information in this transcript. This transcript is not intended to substitute for professional medical advice.

Ruthie: Hello, everyone. Thank you for joining us today. I’m delighted to welcome you to this afternoon’s webinar pair we have an excellent program planned focusing on drug allergies, diagnosis, treatment, and prevention. Before we start today’s program, I would like to cover a few housekeeping details. First, everyone will be muted during the webinar, two minus distractions. We will be recording today’s session and uploaded to our website. You can watch all of our previous recorded webinars and allergy at — at allergyasthma network.org. There will be time at the end for questions. You can send in your questions at any time using the Q&A box at the bottom of your screen. A team member will be checking the chat for any questions, should you need help during the webinar. We will do our best to answer as many questions at the end of the presentation, as possible. This webinar is brought to you in collaboration with the American College of allergy, asthma immunology. The college offers continuing education credits for physicians and attendance credits for others. You can create a free ACA account to earn CME or get credits for these webinars via their member portal. All attendees will receive a certificate of attendance. Please note no other continuing education credits will be provided. If he days after the webinar, you will receive an email containing supplemental information and a link to download the recording. We will share a link in the chat for the certificate of attendance. Today’s presentation is titled drug allergies: Diagnosis, treatment and prevention. Drug allergies constitute a substitute of adverse reactions mediated by the immune system, with a range of — wide range of presentation from rashes. These conditions present substantial challenges in clinical practice, frequently resulting in limitations of treatment options and complexity of care. It is my pleasure to introduce our presenter, an internationally recognized expert in the field. She will guide us through the latest evidence and brother — and best practices. Strategies to improve patient care. Dr. Cassels is a clinical scientist with over 30 years of experience in allergy and immunology and over 200 publications. She is the director of Brigham and Williams Hospital, one of the few nationally and internationally recognized centers of excellence which provides diagnosis, management, treatment options for patients with mast cell activation syndrome. She is actively involved in mast cell related research and is the PI on several clinical trials. She is also the director of the drug hypersensitivity and desensitization Center at Brigham’s and Williams hospital. The center has provided over 900 virus desensitizations per year for the last 20 years to patients with cancer and chronic inflammatory disease. It is my pleasure to hand it over to her for this afternoon’s presentation.

Dr. Castells: Thank you so much. We seek to have a problem with the connection. Do you have — would you be able to put the slides back on? I don’t seem to have access to it. OK, here we are. Thank you very much. It is my great pleasure to share with you today this seminar. One second. Are you able to see my screen?

Ruthie: No.

Dr. Castells: You cannot see my screen, OK. We have a problem with the connection here. Let me see if I can share with you. OK. Here we are. Let’s see if I can share. Are you able to see the screen now?

Ruthie: Yes.

Dr. Castells: OK. Perfect. Thank you so much. I’m delighted to be here with you to review with you a very important topic of drug allergy. The diagnosis, treatment and prevention, and also to go to important topics such as desensitization. My disclosures are here. I work and consult with several companies, and also I write for this. The learning objectives today would be able to assess patients with suspected drug allergies. To develop individualized plans for acute reactions, and also long-term care with patient histories. And then to apply consulting and prevention strategies to enhance patient safety. Let’s start with this. It is seen in 70% of the population. It has actually increased in hospitalized patients, up to 15%. And not all of the patients will be — are allergic we will see that in the next two slides. One thing that is really important is that we see increasing drug allergy and hypersensitivity, due to the longevity of our patients. But also, we have wonderful medications that target inflammatory and protective tissue disorders, cancer, and other diseases. Patients are exposed to either — for longer times. What you see here, what we are trying to do in modern drug hypersensitivity, we have a large network, and we have information that is here from the data that we can see from the patients. We have a lot of knowledge network that at the end of the day, it includes the clinical knowledge, electronic health medical records. And also, we have biomedical research and discovery.

We want our patients to have an accurate diagnosis, we want a targeted treatment, and we want to have improved outcomes. Let me guide you to what we know. We know drug allergy and hypersensitivity has been — we see here that those are described here as anti-body reactions, and delayed reactions. In the antibody reactions, we have type one, which typically would be IG reactions. We know they are more than just IG reactions. We see that in a few minutes. There is what we call type one. And we have reactions that occur because of IG into bodies, cytotoxic reactions. And then we have immuno complexes that drive those reactions. And we have what we call type four reactions. From the severe reactions with systemic symptoms starting — and others. What we call phenotypes is what we actually see. We actually see the patient’s presenting from hives to rashes. What we call endo-types is what is underlying those reactions. Those reactions can be, as we mentioned, IG type reactions but also IG reactions. Deactivation of cells will lead to reactions that are associated with the release of histamine and the symptoms of hives to echo lack six. We have uncovered in the last few years since 2016, we have uncovered that a new mast cell receptor is capable of inducing reactions in patients who are not IG mediated. We see that — we also see that with morphine and some contrast media. When our patients present reactions that are from hives to Aflac six, that have negative skin testing, we don’t have direct tools but we can assume that it is mediated through this scepter.

Now categorize the act — the reactions as immediate reactions. Like we saying, it can occur at first or after several exposures. We have also have reactions to aspirin. And we have delayed reactions where we have a single organ involved that can be with T cells and multiple organ involvement. In those, we have what we call the severe — Those reactions, and a lot of them will be mediated by HLA happily owed hides. We have here an example of what I was mentioning. A severe systemic syndrome with about 5% to 10% mortality induced, associated to 32-1 pair there is an extensive rash that can be peripheral or tissue. It can affect the kidney and the liver. And this can be associated to the expression of this happily or tied. Other drugs have been associated to HLA. In modern allergies, we have to think that HLA genotyping may be part of our evaluation of the patient’s. And you see here for example, that a patient who had a delayed attack reaction to penicillin compound, and when treated with it, this is what we would not like our patients to have. Can these be prevented? Are there tools to identify those reactors? How can this be treated? I think we are going in this direction with modern hypersensitivity. Hypersensitivity to monoclonal checkpoint inhibitors and modulators. These are one of the things we assume. EC patients can present in fusion when they are infused with monochrome’s, and those reactions can present some fever, chills, nausea, may be pain. We have reactions that are type one. Seito can relax — cytokine rely — reactions are exacerbated with more severe fever, chills, pain. Those reactions, we have had success with that. In reactions that are type one reactions

[INDISCERNIBLE]

Those reactions I mentioned to you were not contemplated by that. At that time, there were no antibodies. Infusion reactions are a modern expression of drug hypersensitivity. Cytokine reactions as well. And fixed reactions are something that we are learning as we go. When we look at a patient with a hypersensitivity of reaction, we have to look at what we see, such as a phenotype. What is the drug, the timing of the reaction, what other symptoms, what is the severity of the reaction. We have to try to look at what is underneath the potential reaction, or was it cytokine, is it mixed reaction. And the biomarkers I was mentioning, we will see that biomarkers can be skin testing, can also be in vitro levels. We are looking at mile markers in this way. Tryptase is worth taking for patients that are associated with changes in vital signs. A patient presenting with hives after taking penicillin or chemotherapy drugs. And also presenting with hypertension. Here is elevated to normal range with 11.4. We have 39.2. And it goes back to normal. Here is a patient who had a decent cetacean — desensitization, and goes back to normal. When should we be taking Tryptase?

Within 30 minutes of the symptoms starting. The symptoms should involve two organ systems. That would be the definition of Aflac six and the gastrointestinal. For changes in vital signs. In those patients, we should have tremendous — The patient had an apple lactic reaction. How can we do this? IL-6 is the new biomarker. It is elevated in reactions that we will see. You will see that in those reactions, IL-6 is highly elevated. When the patient’s present with a fever, chills, palpitations, and also with pain. A new biomarker of the drug is IL-6. Skin testing, we all know about skin testing. Skin testing is really available for all the medications that we want to address, not only penicillin. But also chemotherapy and antibodies and others. Again, one of the most important and useful tests is the skin testing. When we look at penicillin skin testing and penicillin allergies in general, we hear about 10% of the general population is thought to have penicillin allergies. But when we evaluate the patient’s one by one, PC less than 1% is totally allergic. This is really something on our plate that we have to define patients who truly have an allergy and who would benefit from using either a medication because they claim to be allergic but one fully evaluated, they do not have it. The process is called the labeling. This is also one of the important tools that we have in drug allergies.

As mentioned, up to 20% of the population will say I am penicillin allergic. What happens with that? Fewer antibiotics are available, the ones available will be more toxic. They use broad-spectrum antibiotics and there is more data where if not — it also has a strong public health implication. There are higher rates of C. diff. There are more costly into biotics that we have to think about. Increased hospital stays. An allergy evaluation will allow us to say, less than 1% of those patients will be allergic. The penicillin allergy impact is well known to all of us. It is — the clinical failure in bacteria or — bacteria, increase of hospital stay. Most importantly, the time of first dose of antibiotic, maybe 50 minutes or more, and acutely in sick patient. The multidrug-resistant infection is really critical in those patients. Over — the increase in the surgical site infections. What do we know about it? Beta-lactam allergies are the most commonly listed allergies. Among all of those individuals, 90% are not going to be allergic. When we confirm the allergy, 80% to 90%, those patients also lose their allergy within 10 years. If a patient had a reaction 40 years ago, the likelihood that today that they are allergic is probably less than 10%.

Penicillin has cross-reactivity is expected to be less than 10%. ther1 sidechain similarity. It’s very rare to find a beta-lactam core allergy. Most of our patients will have reactions and potentially allergies who have similar online chains. By not removing all beta-lactam in the patient would be critical. Most patients are able to tolerate carbo tannins. It is a good time to evaluate those patients. We have to do it at routine outpatients when we see, our patients for the first time they come in for a food Audi. We have to ask the question at that time. We also maybe — at those times, we do have two ask that question. Emergency and inpatient. There is not a site place where we say, we have to do that in our allergy clinics. We have to try to capture the patient’s Intel are colleagues of all of their special. Please ask your patients if you have a penicillin allergy. This is what we call the penicillin chart, available in hospitals. When we have a patient who comes, or they are in need of an antibiotic and they have an — have a history, they can use a fifth generation — if they have a mild reaction, they could do that. Or they could have a test dose with their first and second generations. If the patient had had that severe scars, we have to try to avoid, if there is Aflac six, we may desensitize.

Switching gears to what we have almost forgotten. We had a pandemic of while ago. At the beginning of the pandemic, there was a crisis in terms of people thinking that potential reaction to those vaccines would actually be preventing many people to have the vaccination. You can see here, and we wrote this with Dr. Phillips, that their reactions to vaccines are rare reactions. Not all the reactions are hypersensitivity or allergies. There is also — We have available a lot of tools to evaluate if the patient had hypersensitivity reaction. Those were the recommendations. At the beginning, there was a thought that it may have been part of that. The mRNA vaccines contain those particles. We think there is an extremely rare occurrence. Patients with polythene like all our patients who can actually be vaccinated with good vaccines. What we uncovered, this was done by my colleagues. Mostly in people who had already presented for other medications for vaccines and food, but the majority of them were females and individuals who had — again, here, females were more than 90% of those patients who had had anaphylactic’s. And the reaction to those were within seven minutes.

They occurred very quickly. Importantly, and now we are back to COVID vaccination, most patients who had severe delayed reactions were able to receive the second dose. You see here that this is a really important work from my colleagues at the Mass General Hospital. The first dose you see here is pretty severe, and the second dose. Some of those patients were pre-medicated with an antihistamine. Most, if not all of the second is reactions were smaller. Vaccines and in particular, COVID vaccines, anaphylactic’s is rare there there were no fatalities. Females were more affected. We had vaccinated patients with different disorders. And multiple reactions do not recur. A word of safety for those reactions. Now, let’s talk a little bit of complex allergies. We want to give you an overview of what is a modern approach to reactions. We have here a young woman, 59, who has ovarian cancer. She is treated with chemotherapy. For cancer seems to be under control. She has a reoccurrence two years later. With her exposure, she has shortness of breath.

Her two cases — The patient had anaphylaxis, and we see that her — see that she is elevated. 15 to go this patient — In modern times, we say, let’s evaluate this. This contest is positive and the patient is a great candidate for desensitization. We have done many of those, hundreds of thousands of desensitization’s to patients who otherwise would not be able to use first-line therapies. We have also found those patients that the symptoms that occur are typical symptoms that we know continuous, and we have learned that pain is part of the reactions to chemotherapies. We have here the reaction to those chemotherapies, such as tax lanes and others, may not be related to the chemical structure. It may be related to solvents. They are part of those reactions that we CP those reactions may be related, as we said at the beginning, to the deadline of those medications. We have here a gentleman who has a marginal lymphoma. Responding really well to the chemotherapy. And then he has after the eighth exposure, a reaction. This reaction involves things we had not seen in the previous reaction. Fever and chills. We see this patient has an elevation of IL-6. This is not our typical reaction. It involves an element of cytokine. The patient has a positive test and is capable of also undergoing desensitization. Again, 10 to 15 years ago, this would say you can no longer take it. This is first-line that the patient can be exposed. Our approach to reactions, to the chemotherapies and monoclonal’s, is if the reaction is mild, we can premedicated patients, and we talked to their oncologists or though — or their gastroenterologist.

We can add some premedication in antihistamines and we can do a slower infusion, potentially. Patients with moderate to severe reactions are going to be ending up with desensitization. Induced skin testing for those. For patients with scar, there is a potential for reintroduction of those medications. As I was mentioning, her skin testing, it is a great tool to evaluate those patients and be able to decide what is the risk stratification of our patients. I was mentioning the approved monoclonal antibodies, they are increasing. We have different kinds of monoclonal antibodies, including antibodies. We have wonderful medications that will be available to our patients. The price to pay for those medications is that they are not totally human. Most of those, including this, is likely submitted with different sugars, some of them nonhuman sugars. Reaction to the monoclonal’s are continuing to be seen. In addition to that, we have immuno — patients exposed to that. Those are going to reduce other side effects they have revolutionized cancer care. They are inducing a lot of other immunity, but they are also inducing hypersensitive reactions. We can address those reactions. When we look here at what is the hypersensitivity to monoclonal’s, we see up to 10%. There is a proportional of those patients exposed after multiple exposures, sometimes after first exposure, including the alpha gap. That will continue to react. Our goal is to evaluate those reactions, to understand and evaluate those reactions, to understand their phenotype, Endo type. And to look at the biomarkers, and be able to see if those patients are patients who actually qualify for desensitization. One you look at 104 patients who underwent 526 sub canned — sub containing us intravenous desensitization, a great proportion may have had infusion reactions. And those were not actually desensitized. Most of the reactions were type one reactions. We have cytokine reactions, and mixed reactions. Monoclonal antibodies have a tendency to present those reactions that were not contemplated. Mixed reactions, also non-reactions. Those patients are patients that we can help and treat, then we can identify the reactions and potentially those patients could be desensitized. We see here that we were looking a few years ago, and with the drugs that we had at our center desensitizing. We saw 46% of them, now it is more than 50%, are monoclonal.

Classic reactions would occur. But most — those are humanized. Yet, they use hypersensitive reactions that we can treat. The modern venue that we can address is patients who present these reactions and patients who present type for reactions can be reintroduced to their medication either process of desensitization. Weather in hours or days. End inducing a state of temporary tolerance. We have seen that that happens with aspirin. They can be to sensitized. Now we know those patients with chemotherapy and monoclonal skin can also be desensitized, and can be addressed with therapies. This is a tremendous advance that we have had in the last 10 years. Desensitization is at high risk. They produce a medication that the patient reacted to. They are performed on patients that have chronic inflammatory disease, connective tissue diseases. Either there is no alternative or the alternative has not the same value of the one that we want to do. And want to provide that with first-line treatment. It is antigen specific. We can do that with introducing small doses over an increasing amount of time. Once the desensitization is completed, we can maintain continuous introduction. Are they indications of desensitization? They are. As I was mentioning before, the type to reactions, star reactions, and hepatitis, those are indications for desensitization’s.

Patients who are high risk, for example, in pregnancy, cystic fibrosis, patients with Baha’i comorbidities — with high comorbidities. And patients who are using beta blockers. All of those are at high risk. The indications are such that patients with presenting what we have as type one, mixed reactions, they are candidates for desensitization. Desensitization decision has to be done along with the patients. The patients are scared when they react, they do not want to be exposed. They know that that medication is the best one, they come to us and say, I was on this one, that really controlled my Crohn’s disease. What should I do? We can offer desensitization to those patients, to improve their quality of life. Most of it, their life expectancy with cancer and others. That we have to make that decision along with the patient. In the patient making the decision with us. The principles of desensitization are really something that we have worked in the laboratory. When we desensitize a patient, we are below the threshold of anaphylaxis. Patients who are desensitized have a negative skin tests at the end of the desensitization. Those are lab cells, they have a drug allergen. And when they are activated, they release a histamine. The cell really is an aggravated one. They desensitize it with the same dose. The cells are stable. And we go through the threshold. Desensitization is safe and we have worked out the principles for those patients. IGE with antibiotics, non-IGE, cytokine, mixed reactions, which can occur at first exposure, they are candidates for this. The type for reactions also can be desensitized. This is one of the critical’s and most commonly used for desensitization. Antibiotics and chemotherapy. Diluting the medication, one another thousand, one in 10, going through 1, 2, 3, 4 bags depending on the severity of the reaction, and completing the full dose in about five to six hours is what is accomplished. We can also desensitize patients by other means. We know that females who have progesterone hypersensitivity, where they have acquired using Plan B or when they have IVF. There is this dermatitis that can present as an anaphylaxis. Those patients can be desensitized either orally or in vaginally, or also intramuscularly. All the ways that those sensations can be performed by many ways, not just oral. And the safety, which is critically important, is seen here. The safety is paramount.

Patients who did not react, 70 portrait — 74%. In green, patients who had a mild reaction and are continuing desensitization. 7% of those patients may stop the infusions. Treat that, and able to continue the desensitization. Each graph is its own world. We cannot say we know how to desensitize all the drugs. Because carboplatin is different than something else. We also see the cost of desensitization were contained when we desensitize our patients to their antibiotics. Or how in chemotherapy, we know how those patients are going to have care that can be compounded on the time of the desensitization or electrolytes can be given. The cost may not be higher than the regular infusions. One important caveat is the life expectancy of this patient’s in red is not only here, but somehow better. There is a found reason for us to desensitize patients such as cystic fibrosis. Chemotherapy patients to the ambitions with allergies, and we can do that. The life expectancy in the efficacy of those drugs remains untouched. We have also something that I wanted to mention. Patients who present anaphylactic reactions may have this. It is not a disease, it is a genetic trait. It is present in the general population in 4% to 6% of the general population. It is a location in chromosome 16. Those patients have a high representation in patients with disorders. But also patients who have anaphylaxis. Those patients, the episodes of anaphylaxis can be profound and severe. This is a dominant trait. Patients that we see a pattern of presenting profound reactions to drugs, even to foods. This can also be observed in children with food allergies. When they have the alpha duplication present more profound reactionsl. There is gender typing available for that treat. In our population of patients, we are able to provide those in genotyping care once the patient knows what they had, we can protect them if they have already reacted to medications. Potential future reactions. It is important to know that there are eight nanograms, that is the threshold. If a patient reacts to medication, it is elevated. When we have a second case that we obtain, and the second trip cases eight nanograms, that is potentially a person who has this. That is something that potentially needs to be evaluated in those patients. As we were saying, we can actually approach patients with allergies and ask them what is the phenotype of the reaction. Do we have a type four that is non-scar.

This patients can be reintroduced. Do we have a type three or type two reactions? Those patients cannot be arranged. We have those reactions with cytokine in type one reactions that are candidates for potential desensitization. We see here that a patient with this hypersensitivity is able — this is a young woman with metastatic small lung cancer, reactive to her medication. She had a pretty profound event with swelling. She was desensitized. She could not have a skin test done because of the cost of those antibodies are this is one of the things we are actively working. Skin testing for a lot of the medications that now are providing reactions to patients is off limits because we are not able to have small samples for skin testing of antibodies. We should look into the future of having small doses of that. As I was mentioning before, we are able to now discern those cytokine and mixed reaction and provide that to the patient’s. These are the patients I was mentioning to you. When the initial reaction, it could be that — They can be react — be mixed reactions.

Those patients here in blue, they have no reaction in the neutrality of them. The severity, not reproduced. Those patients are able to tolerate most of the desensitization without reactions what can we do to address patients who have pretty severe type one and anaphylaxis reactions to desensitization? We have the availability of biologicals used for severe asthma. We have actually used this in patients who have been desensitized and have had profound reactions to desensitization, and really needed that medication. The same availability of biologicals is something that we can use for drug allergies. Importantly, I was mentioning to you addressing this cannot be addressed with the desensitization. It has now been addressed with anti-five is one of the targets we have for this severe asthma. Patients who address these symptoms, there are a few studies indicating it can address and it can reduce the disease and reduce the amount of steroids the patient needs. There is ongoing research at our hospital and others that the first-line therapy for severe asthma, it is being evaluated as anti-therapy. This is very new and ongoing. Essentially, we have to approach those biologicals the same way we approach antibiotics and chemotherapies. We have to understand that symptoms we never thought would be symptoms of hypersensitivity are now presenting as back pain and hypotension. IL-6 is in those reactions. Those patients are capable of being desensitized. Research is ongoing. The sensitization cannot be done if there are scars. The reason is a lot these are — we cannot change HLA in this way, by desensitization. We have tools available to us. Practice parameters by Dr. Cannon, although colleagues, everybody in the country that is doing drug allergies was included here. They have the timing of the reactions that we are facing.

You can see here that we have — it does happen within 24, 48 hours. And then fixed drug abruption within that. It occurs many days, after five to seven days. And that drug induced liver injury can occur many weeks after they drug is introduced. It can occur a couple weeks after the drug was introduced. The timing might guide us a little bit. And sometimes, it is the only tool we have to further understand what happened to the patient. Vasculitis can occur up to two months after the patient has been exposed. But once the reactions, like I mentioned at the beginning, there is IGE reactions that occur almost immediately. I have to say an important thing for us to understand his patients who want to go on treatments and chemotherapies are all premedicated. Some of them are premedicated with steroids. That has changed a little bit, the timing. We use to say the immediate reactions were occurring within an hour of the exposure, whether oral or IV. We now say immediate reactions are considered up to six hours, because the patients are premedicated and waning of the antihistamines. It will take about six hours. We consider acute reactions to the ones that occurred within six hours of the introduction of those medications.

I was mentioning this. We have that modern and targeted medication, addressing EGF are. It may actually have this THIQ motive and patients may react to that through this motif. We have seen patients reacting to this reaction. Those are non- THI Q reactions. That is selective for lung cancer, metastatic. Those patients may present with anaphylaxis reactions where we are able to help them with those reactions. I was mentioning also here, this is the study that was published, and patients who presented with COVID. The patients had a pretty profound and significant recovery after being treated with this. This is the modern era and the new era. To finalize, we also have in practice the guidelines that we generated a few years ago that also are living documents that provide you with the guidelines of skin testing, challenges in desensitization. We have been working at the college also providing documents that provide the guidance for skin testing, for challenges and desensitization. This was introduced, last year and this year, we are working on providing documents on chemotherapy monoclonal antibodies.

Again, when evaluating patients, we have many tools that are available to us through the practice parameters, and through tools that we are providing through both societies in terms of, how can we address our patients? As I was mentioning before, to understand this reactions, we look at them, have the patients provide pictures when the reactions occur, typically we are not there, the patient is at home or in the emergency room. A picture is really important. We also are in an era where artificial intelligence is going to help us. We know with programs that are well-defined, the phenotypes of those patients, understanding what is underneath that. And potential treatment avenues, and potential desensitization protocols. Dear working very actively to make all of those tools available to you. Because drug hypersensitivity is increasing. We are all going to be faced with patients who actually need those wonderful medications, and cannot use them unless we provide a good approach, a good understanding of what is happening, and guide with recommendations whether there were — whether the exposure is possible. We will end that here. I would be happy to answer any questions.

Ruthie: Thank you, Dr. Castells for that excellent presentation. You gave us a lot of information to think about. We have a couple of questions. We will answer those. The first question is, why do more children present with amoxicillin rashes these days, but the chemical makeup of the drug, did it change?

Dr. Castells: Why are more children having reactions? Is that the question? That is an excellent question. The same question was posed for food allergies. Why do we have more food allergies now Van when our grandparents were there? Whether the clean hypothesis, where we are more exposed to things. When people have a cold, they take antibiotics. Definitely there is more exposure. There are things that we have to consider like the micro biome. We are changing our micro biomes depending on what we eat, what we are exposed to. Micro biomes are really important. This bacteria we have an error — have in our guts dictates how we will react to foreign things. I think it will be a combined answer of exposure and also micro biome and environmental factors.

Ruthie: Thank you for answering that. Another question is in the case of SCARS, is the recommendation to avoid structurally related drugs? Or would he want to avoid all drugs that commonly cause SCARS?

Dr. Castells: That’s a really good question. With the anticonvulsants, there is an HLA associated with Carbo masses seen. Those drugs that have similar structures. We have to avoid structural related drugs. In the case of penicillin, those can be defined as immuno penicillin. When a scar occurs with one of them, it is possible that we can use nonrelated. . Most of the SCARS are specific. If the structure is similar or the same, those drugs have to be avoided.

Ruthie: Thank you. We will in to one more question before we conclude today. Are there special considerations for evaluating drug allergies in children versus adults?

Dr. Castells: This is a great question also. It should be done very quickly. When a child has a rash during a viral infection, and taking amoxicillin, we cannot wait that the child is 12 or 18 or even an adult. That is actually too late. The recommendation for children is that they should be evaluated shortly after presenting reactions to medications. We have a direct oral challenges from children who have — who are at low risk. Kids who have vomiting symptoms, symptoms not related to hypersensitive reactions, can be labeled by direct oral challenges. This is a modern era that doing that in adults is also possible. It is easier done in children. Those kids have to be done in the first, second, third year of age, and not trailing that label of penicillin, amoxicillin allergy until they are in their 20’s or 40’s. Quick do labeling shortly after their reaction is the recommendation for children.

Ruthie: Thank you. I’m so glad we were able to answer a few questions after today’s webinar. We thank you so much for being with us, Dr. Castells. And for such an engaging presentation. Thank you to all of you for joining us today. We hope this session was able to provide valuable tools and strategies to support you and your practice, the diagnosis, treatment and prevention of drug allergies. In a few days, Zoom will email you a link to this recording along with supplemental information. And a post webinar evaluation. Your feedback is very important to us so please feel free to send that into help us shape the future of this program. Join us on November 19 at 12:00 p.m. Eastern for another advances webinar. We will be talking about managing atopic conditions and food allergies in infants. In this session, our doctor will review current best practices, clinical. — guidelines and approaches to treatment. From everyone here at the allergy announcement network, we thank you for joining us and we look forward to having everyone next month. Thank you.

Dr. Castells: Thank you so much. I enjoyed being here.

Ruthie: Thank you. Have a good afternoon, everyone.