The main antiviral for COVID-19 is Paxlovid, a pill you take at home twice a day for five days. It’s the most widely prescribed COVID antiviral and remains the first-line treatment for people at higher risk of getting seriously ill. Two other antivirals are also available: molnupiravir (Lagevrio), another oral option, and remdesivir (Veklury), which is given by IV at a healthcare facility.
Paxlovid: The Primary Oral Antiviral
Paxlovid is a combination of two drugs packaged together. The first, nirmatrelvir, blocks a key enzyme the virus needs to copy itself. Without that enzyme functioning, the virus can’t assemble new copies and the infection stalls. The second component, ritonavir, doesn’t fight the virus directly. Instead, it slows your body from breaking down nirmatrelvir too quickly, keeping the active drug at effective levels in your bloodstream.
Each dose is three pills taken together: two tablets of nirmatrelvir and one tablet of ritonavir. You take that combination twice a day for five days. Treatment needs to start within five days of your first symptoms, and the sooner the better. Paxlovid is FDA-approved for adults and authorized for adolescents aged 12 and older who weigh at least 88 pounds (40 kg).
The treatment is specifically aimed at people who are more likely to develop severe COVID. That includes older adults, people with chronic conditions like diabetes or heart disease, and those with weakened immune systems. If you’re otherwise healthy and at low risk, your doctor may not prescribe it.
Drug Interactions With Paxlovid
The ritonavir component is the reason Paxlovid comes with a long list of drug interactions. Ritonavir interferes with the same liver enzyme that processes dozens of common medications, which can cause those other drugs to build up to dangerous levels in your body. Some of the most notable medications that can’t be taken alongside Paxlovid include certain heart rhythm drugs (amiodarone, flecainide), cholesterol-lowering statins (lovastatin, simvastatin), some anti-seizure medications (carbamazepine, phenytoin), certain sedatives, and even the herbal supplement St. John’s Wort.
Some of these medications can simply be paused for the five-day treatment course and resumed afterward. Others create risks that rule out Paxlovid entirely. People with severe kidney or liver problems also need dose adjustments or may not be candidates. This is why your prescriber will review your full medication list before writing the prescription. If you take multiple daily medications, have that list ready when you call.
Molnupiravir: The Alternative Pill
Molnupiravir (brand name Lagevrio) works differently from Paxlovid. Rather than blocking a viral enzyme, it introduces errors into the virus’s genetic code as it tries to replicate, producing copies so flawed they can’t function. It’s taken orally, twice daily for five days, and must also be started within five days of symptom onset.
In clinical trials published in the New England Journal of Medicine, molnupiravir reduced the combined risk of hospitalization or death from 14.1% to 7.3% compared to placebo at the interim analysis. One death occurred in the molnupiravir group versus nine in the placebo group over 29 days. These numbers are meaningful but generally considered less impressive than Paxlovid’s efficacy, which is why molnupiravir is typically reserved for adults who can’t take Paxlovid due to drug interactions or other contraindications.
Molnupiravir carries a specific caution around pregnancy. Because of how it works (disrupting genetic copying), women who can become pregnant and their partners should use reliable birth control during and shortly after treatment. It’s not recommended for pregnant women.
Remdesivir: The IV Option
Remdesivir (Veklury) is the only COVID antiviral given intravenously. For hospitalized patients, it has been FDA-approved since 2020. For non-hospitalized patients at high risk of progression, it can also be used as a three-day IV infusion course, but each session requires a visit to a healthcare facility. The treatment window is slightly longer than the oral options, with a start deadline of seven days from symptom onset.
Because it requires IV access and multiple clinic visits, remdesivir is less convenient than the oral antivirals. It’s most commonly used for patients already in the hospital or for those who can’t take either Paxlovid or molnupiravir.
The Five-Day Treatment Window
All three antivirals share one critical requirement: they must be started early. Paxlovid and molnupiravir need to begin within five days of your first symptoms. Remdesivir allows up to seven days. After these windows close, the medications become significantly less effective because the virus has already done most of its damage and the immune system’s inflammatory response, not viral replication, is driving the illness.
This means getting tested quickly matters. If you develop symptoms and you’re in a higher-risk group, test promptly and contact your healthcare provider the same day you get a positive result. Waiting a few days to “see how it goes” can push you past the treatment window.
COVID Rebound After Treatment
Some people who take Paxlovid experience what’s called COVID rebound: symptoms improve during or right after the five-day course, then return a few days later along with a positive test. Estimates of how often this happens vary widely, from under 1% to around 32%, partly because rebound also occurs at similar rates in people who don’t take any antiviral at all (1% to 31%).
The reassuring finding is that rebound episodes are typically mild and short-lived. They rarely lead to severe illness or hospitalization. Research into whether a second course of Paxlovid helps during rebound found it sped up the decline of viral levels but didn’t produce meaningful clinical benefit, largely because the rebound resolved on its own.
Pregnancy and Breastfeeding
Pregnant and breastfeeding women were not included in the original Paxlovid clinical trials, so direct safety data is limited. However, major medical organizations including the American College of Obstetricians and Gynecologists and the National Institutes of Health support offering Paxlovid to pregnant patients at higher risk of severe COVID, based on a careful weighing of benefits and risks. Indirect evidence from long-standing use of ritonavir in pregnant women with HIV has not shown significant birth defect risks, and animal studies on nirmatrelvir haven’t raised teratogenicity concerns either.
Remdesivir safety data in pregnancy is similarly inconclusive but is used on a case-by-case basis. Molnupiravir, because of its mechanism of introducing genetic errors, is the one antiviral specifically flagged to avoid during pregnancy.
Cost and Access
Paxlovid’s list price can be significant without assistance. Pfizer has offered programs to reduce costs: commercially insured patients have been eligible for co-pay savings of up to $1,500 per prescription, potentially bringing their out-of-pocket cost to as little as $0 to $25. Medicare, Medicaid, TRICARE, and uninsured patients have had access through a separate government patient assistance program at no cost, though the terms of these programs can change year to year. If cost is a concern, ask your pharmacy about current assistance options before assuming you can’t afford treatment.