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What Is Paxlovid?

Paxlovid is a prescription antiviral medication containing nirmatrelvir and ritonavir. It is approved in the United States to treat mild to moderate COVID-19 in adults at high risk of progression to severe illness, including hospitalization or death. Nirmatrelvir acts against the virus responsible for COVID-19, while ritonavir increases nirmatrelvir exposure by slowing its breakdown. Paxlovid is taken orally for five days and must be started within five days of symptom onset. It is not approved for preventing COVID-19 before or after exposure.

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What Is Paxlovid?

Paxlovid is a prescription antiviral medication containing nirmatrelvir and ritonavir. It is approved in the United States to treat mild to moderate COVID-19 in adults at high risk of progression to severe illness, including hospitalization or death. Nirmatrelvir acts against the virus responsible for COVID-19, while ritonavir increases nirmatrelvir exposure by slowing its breakdown. Paxlovid is taken orally for five days and must be started within five days of symptom onset. It is not approved for preventing COVID-19 before or after exposure.

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How Does Paxlovid Work?

Nirmatrelvir inhibits the SARS-CoV-2 main protease, also called Mpro or 3CLpro, which the virus needs to process proteins required for replication. Blocking this enzyme interferes with the production of new viral particles. Ritonavir inhibits the CYP3A enzyme system, slowing the metabolism of nirmatrelvir and helping maintain therapeutic drug concentrations. Ritonavir also creates a substantial risk of interactions with other medications. Paxlovid reduces the risk of severe COVID-19 in eligible patients but does not eliminate all possibilities of disease progression or symptom recurrence.

Who Can Receive Paxlovid Treatment?

Paxlovid is approved for adults with mild to moderate COVID-19 who are at high risk of developing severe disease. Risk factors can include older age, certain chronic medical conditions, and immune system impairment. Treatment should begin as soon as possible after diagnosis and within five days after symptoms start. Paxlovid is not approved in the United States for pediatric patients, and treatment eligibility requires consideration of kidney function, liver health, and medication interactions. A clinician reviews current prescriptions, over-the-counter medicines, and supplements before prescribing it.

How Should Paxlovid Be Taken?

The standard adult dose is 300 mg nirmatrelvir with 100 mg ritonavir taken together twice daily for five days, with or without food. Patients with moderate kidney impairment receive 150 mg nirmatrelvir and 100 mg ritonavir twice daily. For severe kidney impairment, including patients receiving hemodialysis, the approved adjusted regimen includes 300 mg nirmatrelvir with 100 mg ritonavir once on day one, followed by 150 mg nirmatrelvir with 100 mg ritonavir once daily on days two through five. Hemodialysis-day doses are taken afterward. Tablets must be swallowed whole, and patients should follow the exact prescribed dose pack.

What Are the Side Effects and Warnings of Paxlovid?

Common adverse effects include an altered sense of taste and diarrhea. Paxlovid carries a boxed warning for significant drug interactions because ritonavir strongly inhibits CYP3A. Certain combinations can cause dangerous increases in medication concentrations or reduce antiviral effectiveness. Serious allergic reactions, severe skin reactions, and liver problems have also been reported. Paxlovid is not recommended for patients with severe liver impairment. Healthcare professionals must review all medications before treatment, including certain heart medicines, cholesterol-lowering drugs, sedatives, and other prescriptions. Patients should report severe rash, breathing difficulties, or jaundice promptly.

Common Questions About Paxlovid

Does Paxlovid treat COVID-19?

Yes. Paxlovid is approved to treat mild to moderate COVID-19 in adults at high risk of progression to severe disease. It must be started within five days of symptom onset.

How long is Paxlovid treatment?

Paxlovid is taken for five consecutive days. The standard regimen is twice daily, but patients with severe kidney impairment follow a reduced once-daily schedule after the first day.

Can Paxlovid interact with other medications?

Yes. Ritonavir can significantly alter the concentrations of numerous medications. A healthcare professional must review all prescriptions, supplements, and over-the-counter products before treatment begins.

Can COVID-19 symptoms return after Paxlovid treatment?

Yes. Some patients experience recurrent symptoms or a positive COVID-19 test after initially improving. COVID-19 rebound can also occur without antiviral treatment.

References

COVID-19 Treatment Clinical Care for Outpatients. Centers for Disease Control and Prevention. https://www.cdc.gov/covid/hcp/clinical-care/outpatient-treatment.html. Date Accessed October 30, 2026.

DailyMed - PAXLOVID (nirmatrelvir and ritonavir) kit. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8a99d6d6-fd9e-45bb-b1bf-48c7f761232a. Date Accessed October 30, 2026.

FDA Approves First Oral Antiviral for Treatment of COVID-19 in Adults. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fda-approves-first-oral-antiviral-treatment-covid-19-adults. Date Accessed October 30, 2026.

Nirmatrelvir and Ritonavir. MedlinePlus. https://medlineplus.gov/druginfo/meds/a622005.html. Date Accessed October 30, 2026.

Oral Nirmatrelvir for High-Risk, Nonhospitalized Adults with Covid-19. The New England Journal of Medicine. https://pubmed.ncbi.nlm.nih.gov/35172054/. Date Accessed October 30, 2026.