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Molnupiravir: an oral treatment for COVID-19?

yael coopermangina-allegretti

Reviewed by Yael Cooperman, MD, written by Gina Allegretti, MD

Last updated: Feb 09, 2022
6 min read


Information about the novel coronavirus (the virus that causes COVID-19) is constantly evolving. We will refresh our novel coronavirus content periodically based on newly published peer-reviewed findings to which we have access. For the most reliable and up-to-date information, please visit the CDC website or the WHO’s advice for the public.

Since the beginning of the coronavirus pandemic, researchers have been focused on finding ways to prevent and treat COVID-19. The availability of COVID vaccines was a big step towards prevention. 

But if you got infected, there weren’t always many options for treatment. Most COVID-19 drugs (like monoclonal antibodies and the antiviral drug, remdesivir) are IV medications reserved for hospitalized patients with severe illness.  

But oral drugs like molnupiravir may offer a treatment solution to reduce the risk of severe disease among people who don’t need hospitalization. Molnupiravir has received emergency use authorization (EUA) from the U.S. Food and Drug Administration (FDA) for the treatment of mild to moderate COVID in people at high risk for developing severe COVID-19 (Merck, 2021-c).



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What is molnupiravir? 

Molnupiravir was first studied as a medication to treat viruses like influenza. However, researchers discovered that it works against other viruses too––including coronavirus (Imran, 2021). The medication works by attacking the virus’s genetic material, preventing it from making more copies of itself (Willyard, 2021; Mendez-Arias, 2021). 

What makes molnupiravir different from other available COVID treatments? The biggest difference is that it’s available in pill form. This opens the door to new possibilities, like treating COVID at home instead of at the hospital. Molnupiravir is sold under the brand names Lagevrio and Molulife.

How effective is molnupiravir at treating COVID? 

Evidence suggests that molnupiravir effectively treats mild to moderate COVID and lowers the risk of hospitalization and death.  

In one clinical trial, people infected with the coronavirus were treated either with molnupiravir or a placebo. After 29 days, 7% of people in the molnupiravir group were hospitalized compared to almost twice as many in the placebo group. There were nine deaths in the placebo group and only one in the molnupiravir group. The study concluded that molnupiravir lowered the risk of hospitalization and death from COVID significantly (Jayk Bernal, 2021). 

In another trial, researchers gave people either molnupiravir or a placebo in the first seven days they showed symptoms. They found that after just four days of treatment, the virus was no longer detectable among any of the participants who took molnupiravir. 

Even though they were treated early, the molnupiravir group still developed protective antibodies within a month of being infected, which indicated that they still might get long-term protection from the virus. This study is not yet peer-reviewed, but the results are encouraging (Fischer, 2021).

Does molnupiravir work against new COVID variants? 

In clinical trials, molnupiravir was equally effective against different strains of the virus, including newer variants like Delta, Mu, and Omicron (Merck, 2021-c; Vangeel, 2021). 

Advantages of molnupiravir 

One of the biggest draws of molnupiravir is that it can be taken by mouth, meaning you don’t necessarily need to be in a hospital to get it. It’s most effective for mild to moderate COVID and can stop symptoms before severe disease sets in, keeping you out of the hospital entirely.

Disadvantages of molnupiravir

When you’re treating an infection, timing is everything. And that’s definitely the case with some antivirals. For example, if you’ve ever taken Tamiflu (also known as oseltamivir) for the flu, you know it has to be taken within the first few days of symptoms for it to work. 

The same is true for molnupiravir. You need to take the medication within five days of symptom onset for it to be effective. There’s no evidence from clinical trials showing any benefit to this drug for advanced or severe disease (Gupta, 2021; Willyard, 2021). 

Since the medication when symptoms first appear, getting the drug distributed to all of the people who come down with COVID is complicated. This is why treatment is mostly focused on people at high-risk of developing severe COVID.

Molnupiravir side effects

Most people who take molnupiravir don’t have many side effects and the ones that occur are usually mild. The incidence of side effects in clinical trials was similar in the treatment and placebo groups. Common side effects include headache, nausea, runny nose, and insomnia (Painter, 2021; Fischer, 2021). 

Where can you get molnupiravir? 

Currently, molnupiravir has EUA in the United States and full authorization in the United Kingdom for COVID treatment in people at high-risk for developing severe disease. Risk factors include people with a history of heart disease, diabetes, or obesity (Merck, 2021-b; Gov.UK, 2021). 

A COVID-19 pill that’s taken at home, keeps you out of the hospital, and prevents severe disease and death is one more tool in our arsenal when it comes to fighting the pandemic. While the drug may not be widely available in the United States, if you’re at high risk of developing severe COVID you may be a candidate for it if you catch the coronavirus. 

In the meantime, the best way to protect yourself from COVID is getting vaccinated, making sure to get a booster shot, and following guidelines regarding handwashing and social distancing. 


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Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.