Nirmatrelvir and ritonavir

Generic name: nirmatrelvir and ritonavir
Brand name: Paxlovid
Dosage forms: oral tablet (150 mg-100 mg (150 mg-100 mg Dose), 150 mg-100 mg (300 mg-100 mg Dose))
Drug class: Antiviral combinations

Medically reviewed by Drugs.com on Apr 9, 2025. Written by Cerner Multum.

What is nirmatrelvir and ritonavir?

Nirmatrelvir in combination with another medicine called ritonavir is used for the treatment of mild-to-moderate COVID-19 in adults who are at high risk for progression to severe COVID-19, including hospitalization or death.

Nirmatrelvir and ritonavir may also be used for purposes not listed in this medication guide.

Nirmatrelvir and ritonavir side effects

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Nirmatrelvir and ritonavir may cause serious side effects. Call your doctor at once if you have:

• liver problems--loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects of nirmatrelvir and ritonavir may include:

• changes in your sense of taste; or

• diarrhea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Related/similar drugs

Warnings

Use only as directed. Tell your doctor if you use other medicines or have other medical conditions or allergies. Some drugs should not be used with nirmatrelvir and ritonavir.

Before taking this medicine

You should not use nirmatrelvir and ritonavir if you are allergic to it.

Some drugs should not be used with nirmatrelvir and ritonavir. Your treatment plan may change if you also use:

• sildenafil (Revatio) when used to treat pulmonary arterial hypertension (PAH);

• lumacaftor, ivacaftor;

• bosentan;

• alfuzosin, colchicine;

• tolvaptan;

• naloxegol;

• finerenone;

• flibanserin;

• lomitapide;

• voclosporin;

• rifampin, rifapentine;

• St. John's Wort;

• heart medicine--ivabradine, amiodarone, eplerenone, dronedarone, flecainide, propafenone, quinidine, ranolazine;

• prostate medicine--silodosin;

• antipsychotic medicine--lurasidone, pimozide;

• ergot medicines--dihydroergotamine, ergotamine, methylergonovine;

• migraine headache medicine--eletriptan, ubrogepant;

• cholesterol-lowering medicine--lovastatin, simvastatin;

• a sedative--triazolam, oral midazolam;

• a cancer medicine--apalutamide, enzalutamide; or

• seizure medicine--primidone, carbamazepine, phenobarbital, phenytoin.

Tell your doctor if:

• you have an HIV-1 infection;

• kidney disease (or if you are on dialysis); or

• you have liver problems or a liver disease such as hepatitis.

It is not known if nirmatrelvir and ritonavir will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Nirmatrelvir and ritonavir can make hormonal birth control less effective, including birth control pills, injections, implants, skin patches, and vaginal rings. Use barrier birth control to prevent pregnancy: condom, diaphragm, cervical cap, or contraceptive sponge.

Ask a doctor if it is safe to breastfeed while using nirmatrelvir and ritonavir.

How should I take nirmatrelvir and ritonavir?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Take nirmatrelvir together with ritonavir twice a day for 5 days.

Your kidney function will need to be tested and your dose or medication schedule may be changed based on the results.

Ask your doctor before stopping this medicine.

Tell your doctor if you do not feel better or if you feel worse after 5 days.

You may take nirmatrelvir and ritonavir with or without food.

Swallow the tablets whole and do not crush, chew, or break them.

You may need frequent blood tests to check your liver function.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Use the medicine as soon as you can, but skip the missed dose if you are more than 8 hours late for the dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking nirmatrelvir and ritonavir?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

What other drugs will affect nirmatrelvir and ritonavir?

Sometimes it is not safe to use certain medicines at the same time. Some drugs can affect your blood levels of other drugs you use, which may increase side effects or make the medicines less effective.

Many drugs can affect nirmatrelvir and ritonavir, and some drugs should not be used at the same time. Tell your doctor about all other medicines you use. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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