9 Things to Know About Paxlovid

Experts answer commonly asked questions about the oral antiviral medication.



Paxlovid has been shown to be 88% successful in reducing severe illness, reduce hospitalization and death from COVID-19 if taken early on in the course of an infection (within 5 days of infection).

Paxlovid is the latest COVID-19 treatment that’s been all over the news. The drug was granted an emergency use authorization (EUA) by the Food and Drug Administration (FDA) in December for anyone ages 12 and older who weighs at least 88 pounds, and is at high risk for severe disease.

Paxlovid is an oral antiviral pill that can be taken at home to help keep high-risk patients from getting so sick that they need to be hospitalized. So, if you test positive for the coronavirus and a health care provider writes you a prescription, you can take pills at home and lower your risk of going to the hospital. It is also often covered by most insurance providers whereas Ivermectin and Hydroxychloroquine are not.

1. How does Paxlovid work?

Paxlovid is an antiviral therapy that consists of two separate medications packaged together. When you take your three-pill dose, two of those pills will be nirmatrelvir, which inhibits a key enzyme that the COVID virus requires in order to make functional virus particles. After nirmatrelvir treatment, the COVID virus that is released from the cells is no longer able to enter uninfected cells in the body, which, in turn, stops the infection. The other is ritonavir, a drug that was once used to treat HIV/AIDS but is now used to boost levels of antiviral medicines.

As a COVID-19 treatment, ritonavir essentially shuts down nirmatrelvir’s metabolism in the liver, so that it doesn’t move out of your body as quickly, which means it can work longer—giving it a boost to help fight the infection.

2. When should I take Paxlovid?

You have to take Paxlovid within five days of developing symptoms. Like all antivirals, Paxlovid works best early in the course of an illness—in this case, within the first five days of symptom onset, says Jeffrey Topal, MD, a Yale Medicine infectious diseases specialist who is involved in determining COVID-19 treatment protocols for Yale New Haven Hospital patients. “Once you’ve been ill with the virus for more than a week, the damage done to the body in a severe case can’t be undone by the antiviral,” he says.

3. How often do I take Paxlovid?

You take three Paxlovid pills twice daily for five days for a full course that adds up to 30 pills. It helps that the pills are packaged in a “dose card,” basically a medication blister pack that allows you to punch out the pills as needed.


4. Is Paxlovid similar to Tamiflu?

“I think it's a good comparison,” says Dr. Roberts. Tamiflu is an antiviral drug that reduces flu symptoms. Both are prescription-only oral antiviral pills given early in illness.

Tamiflu is taken twice a day for five days, and it must be started within 48 hours of flu onset. “When you give a patient Tamiflu beyond that, it doesn’t really change the course of their flu,” Dr. Roberts says.


But there are also differences between the two, starting with the way they were studied, Dr. Topal adds. Researchers showed that Paxlovid can prevent hospitalization and death. But since influenza causes fewer severe cases, clinical trials focused on whether Tamiflu could shorten the length of flu illness—which it did, he says.

5. Can anyone get a Paxlovid prescription?

The FDA authorized Paxlovid for people ages 12 and older who weigh at least 88 pounds. But in order to qualify for a prescription, you must also have had a positive COVID-19 test result and be at high risk for developing severe COVID-19.


That means you must either have certain underlying conditions (including cancer, diabetes, obesity, or others) or be 65 or older (more than 81% of COVID-19 deaths occur in in this group). The more underlying medical conditions a person has, the higher their risk for developing a severe case of COVID-19, according to the CDC.


The hope is that the restrictions on who can take Paxlovid will be relaxed over time. The FDA granted the EUA in December, just as a staggering number of people were infected with Omicron and the need for care skyrocketed, leading to supply issues.

6. How well does Paxlovid work?

When it applied for FDA authorization, Pfizer presented data from a clinical trial conducted between mid-July and early December in 2021. The data showed that participants (all of whom were unvaccinated) who were given Paxlovid were 88% less likely to develop severe illness and death compared to trial participants who received a placebo. (While the recommendation is to take Paxlovid within five days of symptom onset, participants in the clinical trial took the drug within three days.)


Scientists will continue to study the drug’s effectiveness as it is used to treat patients in the real world.

7. Does Paxlovid work against Omicron?

Paxlovid’s clinical trials took place before Omicron became predominant, but Pfizer says the drug works against the highly contagious variant. Three laboratory-based studies claim to back this up—two of those studies were conducted by Pfizer, while the third was done by Pfizer in partnership with the Icahn School of Medicine at Mount Sinai. These studies have not yet been published in peer-reviewed medical journals.3. How often do I take Paxlovid?


You take three Paxlovid pills twice daily for five days for a full course that adds up to 30 pills. It helps that the pills are packaged in a “dose card,” basically a medication blister pack that allows you to punch out the pills as needed.


8. What are the side effects from Paxlovid?

Most people who take Paxlovid should not experience serious side effects, explains Dr. Roberts. “Paxlovid is usually very well-tolerated,” he says. Common side effects, which are usually mild, include an:

  • altered or impaired sense of taste

  • diarrhea

  • increased blood pressure, and

  • muscle aches

Since Paxlovid is cleared by the kidneys, dose adjustments may be required for patients with mild-to-moderate kidney disease, explains Dr. Topal. “For patients with severe kidney disease—or who are on dialysis—or those with severe liver disease, Paxlovid is not recommended; the levels of the drug can become too high and could cause increased side effects,” he says.


It’s worth noting that because Paxlovid is still being monitored in the real world, it is possible that all of the risks are not yet known. (The FDA has provided a fact sheet on Paxlovid with a full list of known side effects.)


9. Can COVID-19 symptoms return after taking Paxlovid?


There have been reports that COVID-19 patients have improved or even tested negative after taking Paxlovid, only to have symptoms flare up again a few days later. The rebound may occur just four or five days after treatment, although symptoms appear to be milder the second time around.


“There isn’t enough data yet to understand why viral rebound after Paxlovid treatment happens. But I caution patients about discontinuing their medication before completing the entire course of treatment,” says Dr. Sharieff. “It’s important take Paxlovid as prescribed — at the right time, in the right way and the right frequency — in order to get the best results.”


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