Nirmatrelvir in combination with ritonavir is an experimental medicine being studied for the treatment of mild-to-moderate COVID-19. This drug is still being studied and all of its risks are not yet known.

The US Food and Drug Administration (FDA) has authorized emergency use of nirmatrelvir in combination with another medicine called ritonavir for the treatment of mild-to-moderate COVID-19 in adults and people 12 years of age and older (weighing at least 40 kg or 88 lbs) who are at high risk for progression to severe COVID-19, including hospitalization or death.

Nirmatrelvir and ritonavir is not authorized for use:

• for initiation of treatment in people needing hospitalization due to COVID-19;
• for prevention before or after exposure of COVID-19; or
• longer than 5 consecutive days.

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

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

Some drugs should not be used with nirmatrelvir and ritonavir, such as those listed below.

• alfuzosin, colchicine;
• sildenafil (Revatio) when used to treat pulmonary arterial hypertension (PAH);
• pain medicine--pethidine, piroxicam, propoxyphene;
• heart medicine--amiodarone, dronedarone, flecainide, propafenone, quinidine, ranolazine;
• antipsychotic medicine--lurasidone, pimozide, clozapine;
• ergot medicine--dihydroergotamine, ergotamine, methylergonovine;
• cholesterol-lowering medicine--lovastatin, simvastatin; or
• a sedative--triazolam, oral midazolam.

Nirmatrelvir and ritonavir should not be started immediately after discontinuation of any of the following drugs:

• rifampin;
• St. John's Wort;
• a cancer medicine--apalutamide; or
• seizure medicine--carbamazepine, phenobarbital, phenytoin.

Tell your doctor if:

• you have liver problems or a liver disease such as hepatitis;
• you have kidney problems;
• you have an HIV-1 infection;
• you are pregnant or breastfeeding; or
• you have any serious or chronic disease.

COVID-19 is more likely to cause serious illness or death in a pregnant woman. Not all risks are known yet, but being treated with nirmatrelvir and ritonavir is likely to be less harmful than being infected with COVID-19 during pregnancy.

Ritonavir can make birth control pills or skin patches less effective. Ask your doctor about other birth control options such as an injection, implant, vaginal ring, condom, diaphragm, cervical cap, or contraceptive sponge.

Use Nirmatrelvir And Ritonavir (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

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).

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).

Ritonavir affects your immune system, which may cause certain side effects (even weeks or months after you've taken this medicine). Tell your doctor if you have:

• signs of a new infection--fever, night sweats, swollen glands, cold sores, cough, wheezing, diarrhea, weight loss;
• trouble speaking or swallowing, problems with balance or eye movement, weakness or prickly feeling; or
• swelling in your neck or throat (enlarged thyroid), menstrual changes, impotence.

Common side effects may include:

• changes in your sense of taste;
• diarrhea;
• elevated blood pressure; or
• muscle pain.

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.

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