Published June 14, 2022. This post will be updated when new information becomes available.

Since the beginning of the COVID-19 pandemic, scientists have researched treatments for COVID-19. Most of these treatments have been administered intravenously and usually in a hospital setting.

We now have two COVID-19 antiviral pills available – available from Merck/Ridgeback Biotherapeutics and Pfizer.

The pills are considered a major step forward in the fight against the pandemic.

What antiviral pills for COVID-19 are currently available?

Until recently, there was not a specific COVID antiviral pill approved for treating COVID-19. Researchers have been working on effective treatments and, obviously, a pill, which could be taken at home is ideal.

There are several treatments for COVID-19, but most are not available in a pill form and are limited to use for hospitalized patients. Monoclonal antibody treatments are very effective in treating COVID-19, but they are given by intravenous infusion or injection. They require monitoring by a healthcare professional. This can limit access.

That is why the news coming from two recent clinical trials is so exciting. They point to an oral therapy effective at preventing severe illness from COVID-19. The bonus is that they can be taken in the safety of home. For those patients at high-risk for severe disease, this news may be especially welcome.

On October 1, 2021, Merck, and Ridgeback Biotherapeutics released findings from clinical trials on an oral antiviral drug to treat COVID-19. The Merck/Ridgeback pill is called molnupiravir (brand name Lagevrio).

On November 5, 2021, Pfizer announced findings from their clinical trials on an oral treatment for COVID-19. Pfizer’s Paxlovid is a combination of nirmatrelvir and the HIV drug, ritonavir.

Research shows both medications were effective in preventing hospitalizations and death from COVID-19 infection.

Both medications received an emergency use authorization (EUA) from the U.S. Food and Drug Administration (FDA) in December 2021.

Photo of woman pharmacist taking a medicine from the shelf, wearing lab coat during work in a modern drugstore with various pharmaceutical products.

Who should get a COVID-19 antiviral pill?

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:

  • asthma
  • COPD
  • lung diseases
  • heart disease
  • diabetes
  • 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; it 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.

How soon can Americans get a COVID-19 antiviral pill?

If you have been recently diagnosed with COVID-19, you may be asking, “How can I access the COVID pill?” First, discuss this treatment option with your doctor to find out if a COVID-19 pill is right for you.

Since both Paxlovid and molnuapiravir received their EUAs, doctors are now able to prescribe the medications.

How much and how often should you take COVID-19 antiviral drugs?

Both Paxlovid and molnupiravir should be taken within 5 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, given twice-daily for five days. It is a total of 3 pills 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 4 pills twice a day.

Concept photo of closeup of pills, the Covid Pill is highlighted and the rest are in the dark.

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?

Current data suggest that both Paxlovid and molnupiravir are effective treatments to those infected with the Omicron COVID-19 variant

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 molnipiravir and distributed them to states, with the purpose of providing the medications at no cost to the public.

Keep in mind that supplies of COVID-19 pills may be tight to start but should ramp up as more are made available  in the months ahead.

What is the cost if federal and state governments are no longer able to provide them free of charge? It’s reported that a full course of treatment for molnupiravir costs around $700, while Paxlovid is about $530. Check with your doctor and/or health insurance provider.

Concept photo of scientist doing medical research on the Covid Pill

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
  • copovidone
  • sorbitan monolaurate
  • hydroxypropyl cellulose
  • hypromellose
  • polyethylene glycol 40
  • polyethylene glycol 3350
  • polysorbate 80
  • talc

Merck and Ridgeback’s molnupiravir active ingredient is molnupiravir, with additional ingredients as part of the capsule and printing:

  • molnupiravir
  • croscarmellose sodium
  • hydroxypropyl cellulose
  • magnesium stearate
  • microcrystalline cellulose
  • Hypromellose
  • titanium dioxide
  • red iron oxide
  • butyl alcohol
  • dehydrated alcohol
  • isopropyl alcohol
  • potassium hydroxide
  • propylene glycol
  • purified water
  • shellac
  • 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 the potential risk of side effects and/or may cause an allergic reaction. That is why it is important to know your allergies, make sure they are updated with your doctors and pharmacy, and to read ingredient lists. If you are allergic to any of the ingredients of a medicine, avoid taking it.

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.

Do the COVID-19 antiviral pills interact with other medications and can this lead to a severe reaction?

Both Paxlovid and molnupiravir pills can interact with other medications a person is taking and cause a severe reaction.

NIH 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. 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.

What’s the difference between the Pfizer and Merck COVID-19 antiviral drugs?

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?

While the news about a COVID-19 antiviral pill is exciting, they are not an oral COVID-19 vaccine. They should not be a replacement for vaccination. Remember that COVID-19 vaccines are highly effective in preventing infection. Consider these new medications as another tool in the toolbox used to address the pandemic.

Does the new COVID-19 pill contain ivermectin?

You may be asking, “Is this the same COVID 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

Will there be a COVID-19 pill mandate?

There is no reason to think the federal government or state governments will issue a pill mandate for people diagnosed with COVID-19. There is however a long history of vaccine mandates as a public health measure.

If you are diagnosed with COVID-19, work with your doctor or a healthcare professional to determine the best treatment for you.


Reviewed by
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.