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Nirmatrelvir and ritonavir

Brand names: Paxlovid

Paxlovid is an antiviral pill that lowers the risk of severe COVID-19 in people at higher risk. It must start within 5 days of symptoms.

Brand namesPaxlovid
Type of medicineAntiviral (COVID-19 medicine)
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

Ritonavir boosts nirmatrelvir but interacts with many medicines, so a pharmacist should review everything you take.

What it's used for

  • Mild to moderate COVID-19 in adults and some children at high risk of severe illness

How to take it

  • Take all the pills in each dose together, twice a day, for 5 days.
  • Start as soon as possible after a positive test.
  • Tell your provider about every medicine and supplement.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Altered or metallic taste
  • Diarrhea
  • Higher blood pressure
  • Muscle aches
Call 911Swelling of the face, lips, or throat, hives, or trouble breathing
Call 911A blistering, peeling, or widespread red rash, especially with fever
Call 911Trouble breathing, chest pain, or confusion (COVID getting worse)
Call your provider todayYellow skin or eyes

Warnings

  • Boxed warning: serious interactions with many medicines.
  • Doses are lower with kidney disease.

Other medicines, foods, and alcohol

  • Many medicines must be paused or adjusted, including some statins, blood thinners, heart rhythm medicines, sedatives, and seizure medicines.
  • St. John's wort and rifampin make it less effective.
  • It can make hormonal birth control less effective.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

It can be used in pregnancy. Talk with your provider.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember. If it's almost time for the next dose, skip the missed one. Don't double up, and still finish the full course.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.