Updated June 15, 2023. This post will be updated when new information becomes available.
Two COVID-19 antiviral pills are available and now one is fully approved by the U.S. Food and Drug Administration (FDA). The FDA fully approved Paxlovid in May 2023 for adults who are at risk for severe illness. It continues to be approved under an Emergency Use Authorization (EUA) for children ages 12-18 at risk for severe illness.
The antiviral pills have been a major step forward in the fight against the COVID-19 pandemic. Prior to the pills, most COVID-19 treatments were administered intravenously and usually in a hospital. Monoclonal antibody treatments are effective in treating COVID-19, but they require monitoring by healthcare providers. This can limit access.
Two COVID-19 antiviral pills are available, one from Pfizer and one from Merck/Ridgeback Biotherapeutics:
- Paxlovid – fully approved by FDA, it is a combination of nirmatrelvir and the HIV/AIDS drug ritonavir (Pfizer).
- Molnupiravir – approved under an EUA, its brand name is Lagevrio (Merck/Ridgeback Biotherapeutics).
The antiviral pills are designed to prevent severe symptom onset from COVID-19. The antiviral therapy can be taken at home, making this antiviral treatment ideal for many patients.
Clinical trials showed both medications were able to help prevent hospitalization and death from COVID-19 infection.
Paxlovid and molnupiravir are approved for people with mild or moderate COVID-19 who are more likely to become seriously ill. These include people with chronic diseases such as:
- lung diseases
- heart disease
- a compromised immune system
Paxlovid is authorized for patients who are 12 years of age and older. Molnupiravir is approved only for adults 18 years of age or older. Molnupiravir is not recommended for use by pregnant women.
People with asthma or COPD should talk with their doctor about using their asthma medications while taking Paxlovid. Long-acting beta-agonists (LABA) taken with Paxlovid may cause cardiac risks. Salmeterol, in particular, may need to be withheld during Paxlovid treatment. Certain inhaled corticosteroids taken with Paxlovid may put patients at increased risk for Cushing’s syndrome and adrenal suppression.
In most cases, the benefits of a short course of Paxlovid to treat COVID-19 will outweigh the potential risks. It may be more dangerous to stop taking asthma medication even for a short period of time. That’s why it’s important to talk with your doctor about the risks and any possible alternative medications.
Learn more about Paxlovid from FDA.
If you test positive for COVID-19, you may ask, “How can I get access to the COVID pill?” Discuss this treatment option with your doctor to find out if a COVID-19 pill is right for you.
Doctors can prescribe Paxlovid and molnupiravir to people with a positive COVID-19 test; or to people who are diagnosed with COVID-19 based on symptoms or recent exposures to others with COVID-19.
While it’s recommended you see your doctor for Paxlovid, FDA has also authorized state-licensed pharmacists to prescribe Paxlovid with certain limitations. Patients should provide the following information to the pharmacist:
- electronic or printed health records less than 12 months old;
- a list of all medications you are taking so the pharmacist can screen for drugs that may interact with Paxlovid.
Remember, Paxlovid is not for everyone. Doctors prescribe Paxlovid for people who are at high risk for severe disease. It may help treat mild symptoms but only in people who may progress to severe disease. In fact, a recent Pfizer study indicated Paxlovid may not benefit patients who are low-risk for severe illness and are vaccinated.
Pharmacists should refer patients to doctors for special considerations. These considerations may include possible drug interactions with Paxlovid.
Both Paxlovid and molnupiravir should be taken within five days of experiencing COVID-19 symptoms.
Paxlovid is given at a dose of 300 mg (two 150 mg tablets) of nirmatrelvir with one 100 mg tablet of ritonavir, twice-daily for five days. It is a total of three tablets twice a day.
Molnupiravir is given at a dose of 800 mg (four 200 mg tablets) every 12 hours for five days. This is a total of four pills twice a day.
How does the COVID pill work?
Both the Paxlovid and molnupiravir pills work by limiting the ability of the virus to replicate. Molnupiravir is a type of nucleoside analog. Paxlovid is a protease inhibitor. Both these types of medications have been valuable in the fight against HIV/AIDS.
Paxlovid is a combination of two medications: nirmatrelvir, which stops the virus from replicating, and ritonavir, which stops nirmatrelvir from breaking down.
Merck and Ridgeback’s molnupiravir has been shown to reduce the risk of hospitalization and death by 30%. In patients who received molnupiravir, 6.8% were hospitalized. This is compared to 9.7% of placebo patients who were hospitalized. Nine deaths were reported in those who received a placebo and one in molnupiravir group. The incidence of drug-related adverse events was comparable between those who received molnupiravir (12%) and those who received a placebo (11%).
Pfizer’s Paxlovid has been shown to reduce the risk of hospitalization and death by 89% as compared to a placebo. In patients who received Paxlovid, 0.8% were hospitalized. This is compared to 7.0% of patients who received placebo and were hospitalized or died. There were no deaths reported in those who received Paxlovid. The incidence of treatment-emergent adverse events was 19% in those that received Paxlovid compared to 21% in those that received a placebo.
According to the National Institutes of Health (NIH), molnupiravir has been shown to be effective against all RNA (ribonucleic acid) viruses while Paxlovid “has demonstrated antiviral activity against all coronaviruses that are known to infect humans.”
Do the COVID pills work for the Omicron variant?
Both Paxlovid and molnupiravir are effective treatments to those infected with the Omicron variants.
How much is the pill for COVID?
Paxlovid and molnupiravir are free at this time. The federal government purchased large supplies of both Paxlovid and molnupiravir and distributed them to states, with the purpose of providing the medications at no cost to the public.
What is the cost if federal and state governments are no longer able to provide them free of charge? It’s uncertain at this time. A starting point to determine the cost is using what the U.S. government paid for the medications: Paxlovid cost about $530 per course. Molnupiravir cost about $700 per course. Check with your health insurance provider to see if it will be covered.
What are the COVID pill ingredients?
Pfizer’s Paxlovid is a combination of the two active ingredients, nirmatrelvir and ritonavir. Additional inactive ingredients include:
- colloidal silicon dioxide
- croscarmellose sodium
- lactose monohydrate
- microcrystalline cellulose
- sodium stearyl fumarate
- hydroxypropyl methylcellulose
- iron oxide red
- polyethylene glycol
- titanium dioxide
- anhydrous dibasic calcium phosphate
- sorbitan monolaurate
- hydroxypropyl cellulose
- polyethylene glycol 40
- polyethylene glycol 3350
- polysorbate 80
Merck and Ridgeback’s active ingredient is molnupiravir, with additional ingredients as part of the capsule and printing:
- croscarmellose sodium
- hydroxypropyl cellulose
- magnesium stearate
- microcrystalline cellulose
- titanium dioxide
- red iron oxide
- butyl alcohol
- dehydrated alcohol
- isopropyl alcohol
- potassium hydroxide
- propylene glycol
- purified water
- strong ammonia solution
If you are allergic to any of the active or inactive ingredients to these medications, make sure to let your doctor know and discuss risks vs. benefits.
Do COVID-19 pills have side effects or allergens?
Medications always have a risk for potential side effects and/or may cause an allergic reaction. That is why it is important to know your allergies. Make sure your healthcare records are updated with your doctors and pharmacy. And be sure to read ingredient lists of medications.
If you are allergic to any of the ingredients of a medicine or vaccine, don’t take it. Instead, talk with your doctor. There may be alternative medicines or vaccines available.
Does Merck/Ridgeback’s COVID-19 pill have side effects?
According to the FDA patient fact sheet for molnupiravir, side effects include nausea, dizziness, and diarrhea.
Molnupiravir is not recommended for use by pregnant women as some studies indicate it could impact the development of a fetus. It’s also not recommended for women who are breastfeeding.
In addition, scientists are studying how molnupiravir affects sperm in men and whether it could impact the development of a fetus. It is recommended that sexually active men use a reliable method of birth control while taking molnupiravir and for at least 3 months after the last dose.
Does Pfizer’s COVID-19 pill have side effects?
According to the FDA patient fact sheet, Paxlovid may cause liver problems, resistance to HIV medications, an altered sense of taste, diarrhea, high blood pressure, and muscle aches. Most side effects are reported as mild.
Both Paxlovid and molnupiravir pills can interact with other medications a person is taking and cause a severe reaction.
The National Institutes of Health has posted a list of medications that may interact with Paxlovid. The list includes salmeterol, which is a long-acting beta2-agonist (LABA) medication used to treat asthma and COPD. Salmeterol taken with Paxlovid may cause cardiac risks. Paxlovid can also interact with medications such as statins, blood thinners and some antidepressants.
It’s important to tell your doctor all of the medications you’re taking and whether any of them will interact with the COVID-19 pill. The doctor may withhold the COVID-19 pill and/or prescribe an alternative COVID-19 therapy.
Both Paxlovid and molnupiravir are classified as antiviral medications.
Paxlovid is a protease inhibitor. Protease is an enzyme which works by chopping up viral proteins into smaller portions so they can spread easily. Protease inhibitors work by poisoning the protease so the viral protein chain remains long and cannot effectively replicate.
Molnupiravir is a nucleoside analog and works by inserting errors into the virus’s genetic code. This interferes with the virus’s ability to replicate itself.
The common thread with both medications is they limit the ability of the COVID-19 virus to replicate. Viruses replicate very quickly at the beginning of an illness, so that is why it is important for these pills to be taken as early as possible from the onset of symptoms. The longer the virus has to replicate, the more challenge to reducing symptoms and risk.
Can I take a COVID-19 pill instead of a vaccine?
The COVID-19 antiviral pill is not a replacement for vaccination. The pill treats COVID-19 and prevents severe symptoms in people already diagnosed with the condition and who are at high risk for severe illness. The COVID-19 vaccines can help prevent infection and reduce the risk of severe illness but they do not treat COVID-19 after diagnosis.
Consider the antiviral pills as another tool in the toolbox to treat COVID-19.
Does the new COVID-19 pill contain ivermectin?
You may be asking, “Is this the same COVID-19 pill that’s also for horses?” The answer is no. The “horse pill” is ivermectin. Ivermectin is an antiparasitic approved to treat some tropical diseases in humans. It is also used to deworm livestock, including horses. Ivermectin is not approved to treat COVID-19.
Neither the pill from Merck/Ridgeback or Pfizer contains ivermectin. They have different chemical structures and compositions.
Purvi Parikh, MD, FACAAI is an adult and pediatric allergist and immunologist at Allergy and Asthma Associates of Murray Hill in New York City. She is on faculty as Clinical Assistant Professor in both departments of Medicine and Pediatrics at New York University School of Medicine.