Paxlovid is an antiviral medication used to treat mild to moderate COVID-19 in people who are at high risk of becoming seriously ill. It works by stopping the virus from replicating inside your body, and in its pivotal clinical trial, it reduced the risk of hospitalization or death by 89% compared to placebo. The treatment is a five-day course of pills taken twice daily, and it must be started within five days of your first symptoms to be effective.
Who Qualifies for Paxlovid
Paxlovid is approved for adults and for adolescents over 12 who weigh at least 88 pounds (40 kg). The key requirement is that you have at least one risk factor for developing severe COVID-19. It is not intended for people who are already hospitalized with severe illness, nor for otherwise healthy people with a low risk of complications.
Risk factors that may make you eligible include:
- Age over 65, with risk increasing substantially above 75
- Being unvaccinated or not up to date on COVID-19 vaccinations
- Chronic medical conditions, especially when multiple conditions are present (diabetes, heart disease, obesity, chronic lung disease, and others)
- Weakened immune system, whether from a condition like HIV or from medications such as chemotherapy
- Living in a long-term care facility
Your doctor may also consider factors not on a standard checklist. Clinical judgment plays a role, particularly when someone has a combination of moderate risks that together raise their overall vulnerability.
How Paxlovid Works
Each dose of Paxlovid contains two separate medications that work together. The first is the active antiviral, which blocks an enzyme the coronavirus needs to process its proteins and assemble new copies of itself. Without that enzyme functioning, the virus can’t replicate.
The second component doesn’t fight the virus directly. Instead, it slows down your liver’s ability to break down the antiviral, keeping it active in your bloodstream longer and at higher concentrations. This “booster” approach is well established in medicine and has been used in HIV treatment for decades. The downside is that this same liver-slowing effect can interfere with many other medications, which is why your prescriber will carefully review everything you’re taking before writing a prescription.
The Five-Day Treatment Course
The standard regimen is three pills taken together, twice a day, for five days. You take them with or without food. Timing matters: treatment should begin as soon as possible after a positive test and symptoms, and it must start within five days of symptom onset. The earlier you start, the better the drug works.
If you have moderate kidney disease, your prescriber will reduce the dose. You’ll take two pills instead of three at each dose, but the five-day schedule stays the same. Paxlovid is not currently recommended for people with severe kidney disease or severe liver disease.
How Effective It Is
The original randomized trial, called EPIC-HR, tested Paxlovid in unvaccinated people with no prior infection during a period before the Omicron variant dominated. In that group, treatment reduced the risk of hospitalization or death by 89%. Real-world studies conducted later, during Omicron and in populations with more immunity from vaccines and prior infections, have generally shown smaller but still meaningful benefits. The drug remains one of the most effective outpatient treatments for COVID-19, particularly for older adults and immunocompromised patients.
Common Side Effects
The most talked-about side effect is what people call “Paxlovid mouth,” a metallic or bitter taste that can linger between doses. In clinical trials, about 5% of people taking Paxlovid reported this altered taste, compared to less than 1% on placebo. Diarrhea is the other common side effect, occurring in about 3% of treated patients. Both typically resolve after you finish the course. Serious side effects are rare.
COVID Rebound After Treatment
Some people experience a return of symptoms or a positive test a few days after finishing Paxlovid. This “rebound” phenomenon got significant attention, but the data suggest it’s less unique to Paxlovid than early reports implied. A large retrospective study found rebound rates of about 6.6% in people treated with Paxlovid and 4.5% in untreated people, a difference that was not statistically significant.
That said, some smaller observational studies have reported higher rebound rates, ranging from 10% to 14% in treated patients, and one prospective study found symptom rebound in about 32% of treated individuals compared to 20% of untreated ones. The wide variation likely reflects differences in how rebound was defined and measured. What’s consistent across studies is that rebound episodes are generally mild and do not lead to hospitalization. If your symptoms return after finishing treatment, you don’t need a second course of Paxlovid, but you should isolate again while symptomatic.
Drug Interactions to Watch For
Because of the way Paxlovid’s booster component affects liver enzymes, it interacts with a long list of medications. Some of the most common conflicts involve certain cholesterol-lowering drugs, blood thinners, heart rhythm medications, anti-seizure drugs, and some sedatives. Certain herbal supplements, including St. John’s wort, can also cause problems by reducing Paxlovid’s effectiveness.
Your prescriber or pharmacist will screen for interactions before dispensing the medication. In some cases, a conflicting drug can be temporarily paused for the five-day treatment window. In others, Paxlovid may not be safe to use, and an alternative COVID-19 treatment would be considered instead. Being upfront about every medication and supplement you take, including over-the-counter products, is essential to using Paxlovid safely.