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.

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).

The combination of nirmatrelvir and ritonavir comes as tablets to be taken by mouth. The nirmatrelvir and ritonavir must be taken together for the medication to work correctly. It is usually taken with or without food two times a day for 5 days. Take nirmatrelvir and ritonavir at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take nirmatrelvir and ritonavir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not split, chew, or crush them.

Take nirmatrelvir and ritonavir until you finish the prescription, even if you start to feel better. Do not stop taking nirmatrelvir and ritonavir without talking to your doctor. If you stop taking nirmatrelvir and ritonavir too soon or skip doses, your infection may not be completely treated.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

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 (two tablets of nirmatrelvir and one tablet of ritonavir) twice a day for 5 consecutive days.

Take nirmatrelvir and ritonavir as soon as possible after diagnosis of COVID-19 and within 5 days of when symptoms first appear.

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.

Being treated with nirmatrelvir and ritonavir will not make you less contagious to other people. Keep using infection control methods such as self-isolation, social distancing, hand-washing, using protective face covering, disinfecting surfaces you touch a lot, and not sharing personal items with others.

Nirmatrelvir and ritonavir are still being studied and all of the risks are not yet known.

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 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.

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

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

Unless your doctor tells you otherwise, continue your normal diet.

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

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).

Ritonavir affects your immune system, which may cause certain side effects (even weeks or months after you've taken nirmatrelvir and ritonavir). 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 of nirmatrelvir and ritonavir 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.

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.

Keep all appointments with your doctor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

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

You should continue to isolate as directed by your doctor and follow public health practices such as wearing a mask, social distancing, and frequent hand washing.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.