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What to know about antiviral pills to treat COVID-19

A man wrapped in a blanket holds a mug and rests his head on his hand.

There are two kinds of pills OK'd by the U.S. Food and Drug Administration (FDA) for emergency use to treat COVID-19 at home. These medicines may help keep certain people who test positive for COVID-19 from getting very sick.

Here are some key questions and answers about these COVID-19 treatment options, with information from FDA.

What are they?

The first drug is Pfizer's Paxlovid. Paxlovid is authorized for adults and children 12 and older who test positive for COVID-19 and have a high risk for severe illness. This includes people with underlying health conditions.

Paxlovid consists of nirmatrelvir and ritonavir taken together. During treatment with Paxlovid, three tablets are taken twice a day for five days.

The other drug is Merck's molnupiravir. Molnupiravir (Lagevrio) is only for adults with COVID-19 who are at high risk of severe illness. It should not be used to treat children with COVID-19. This is because it may affect bone and cartilage growth. With molnupiravir, four capsules are taken every 12 hours for five days.

Molnupiravir does not work as well as Paxlovid. For this reason, it should only be used when other COVID-19 treatments (like Paxlovid) are not available or cannot be used.

Do they work?

Yes. But they must be started as soon as possible—within five days of getting COVID-19 symptoms.

In the clinical trials, among people at high risk for getting severely sick from COVID-19:

  • Paxlovid reduced the risk of being hospitalized for COVID-19 or dying by 88%.
  • Molnupiravir reduced the risk of hospitalization or death by 30%.

How do they work?

Paxlovid interferes with a protein on the coronavirus. This helps keep the virus from making copies of itself. Molnupiravir introduces errors in the genetic code of the virus to help keep it from replicating.

Are they safe?

Before issuing emergency use authorizations (EUAs) for Paxlovid and molnupiravir, FDA looked at the scientific evidence. The agency decided that the benefits of these treatments outweigh any risks.

What are the risks and side effects?

All medicines may cause side effects. The side effects of Paxlovid may include:

  • Diarrhea.
  • High blood pressure.
  • Muscle aches.
  • Reduced sense of taste.

Some of the potential risks of Paxlovid include:

  • Experiencing a bad reaction from taking the drug at the same time as certain other drugs. Be sure to tell your doctor about all the other medicines you take.
  • Making HIV treatment drugs less effective for people with uncontrolled or undiagnosed HIV.
  • Making liver or kidney problems worse.

The side effects of molnupiravir may include:

  • Diarrhea.
  • Nausea.
  • Dizziness.

Molnupiravir is not recommended for pregnant women. Animal studies found that it may harm the fetus. And there is a risk that molnupiravir may affect sperm cells.

Sexually active men and women who use molnupiravir should use contraception to avoid a pregnancy during and after treatment. Women who used molnupiravir should prevent pregnancy for four days after treatment is completed. Men who used molnupiravir should use contraception for at least three months after treatment.

How do you get them?

You will need a prescription from a doctor.

Remember: Both of these COVID-19 treatment options should be started as soon as possible. So if you think you might have COVID-19, call your doctor. Your doctor might recommend a COVID-19 test.

Reviewed 4/18/2023

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