Paxlovid is an antiviral pill that was granted emergency use authorization (EUA) last December by the Food and Drug Administration (FDA) for the treatment of COVID-19. If you test positive for the virus (from a home test or one given by your doctor), your doctor can prescribe Paxlovid to be taken at home. The Pfizer drug has been found to reduce the risk of hospitalization and death by 89% and is effective against the omicron variant.

Dr. Scott Roberts, an infectious disease specialist at Yale Medicine tells Eat This, Not That!, “It’s really our first efficacious antiviral pill for this virus, and it can really prevent hospitalization and death in people who are at high risk.”

Here are 10 important facts to know about Paxlovid:

1. How it works. Paxlovid is a three-dose antiviral treatment that’s composed of two medications packaged together. Two of those pills are nirmatrelvir, a drug that stops the virus from reproducing. The third is ritonavir, a medication boosts the levels of antiviral drugs.
2. When to take the medication. Patients must take 30 pills over a five-day period. Paxlovid must be started within five days of symptoms, says STAT News.
3. Who can get a prescription for the drug? The FDA authorized Paxlovid for individuals aged 12 years and older, says Eat This, Not That! But you must also have a positive COVID-19 test and prove that you are in the high-risk category. This means you are 65 or older, or have underlying medical conditions, such as cancer or diabetes. Consult with your doctor to determine if you are a high-risk.
4. Does Paxlovid work in children?  Experts at Yale Medicine say that while the drug is authorized for use in adolescents and teenagers ages 12 years and up, and weighing at least 88 pounds, that group wasn’t tested in the original clinical trial. But because many children reach 88 pounds the FDA has allowed extensions for emergency use authorization in those who may be at high risk due to underlying medical conditions.
5. Is it effective? Pfizer presented the FDA with clinical data that showed unvaccinated study participants given Paxlovid were 89% less likely to develop severe illness or die compared to participants who received the placebo.
6. Does Paxlovid work against omicron? Pfizer asserts that its drug works well against the highly contagious variant and has three laboratory-based studies to back this up.
7. What are the side effects of Paxlovid? According to Roberts, most people who take Paxlovid will not experience serious side effects. Common side effects, which include impaired sense of taste, diarrhea, increased blood pressure and muscle aches, are typically mild.
8. Does the drug react with other medications? There is a long list of potential interactions when Paxlovid is taken with other medications, according to Yale Medicine, and some can lead to serious complications.  Paxlovid can decrease the metabolism of blood thinners that many older adults depend upon, driving up levels of those medications in the body to a point where they are unsafe. WebMD compiled a comprehensive list of cautionary combinations. However, it is best to check with your healthcare provider or pharmacist to be sure Paxlovid is right for you.
9. What is the rebound effect of Paxlovid? There have been several reports of a “rebound” of COVID-19 symptoms after people have completed the five-day course of the drug. “This is being closely investigated and we should have guidance soon,” said Roberts.
10. Do I still need to stay up to date with vaccinations if Paxlovid is available? Vaccination is still a key part of prevention, says Yale’s Jeffrey Topal, M.D. Picture a pyramid, he says, with vaccination and mitigation efforts, such as masking and testing, forming the base of the pyramid and medication at the top point. “Early testing is key to making these medications work,” he said. “It’s always been the Achilles’ heel of these antiviral drugs that most people don’t get tested — or they don’t have access to testing.” Topal says that while home tests aren’t as sensitive as PCR tests, they are still very helpful at making a diagnosis.