Cobicistat is given together with atazanavir (Reyataz) or darunavir (Prezista) to treat human immunodeficiency virus (HIV), the virus that can cause acquired immunodeficiency syndrome (AIDS).

Cobicistat is used to increase your blood levels of these medicines, helping to make them safer and more effective at lower doses.

Cobicistat is not an antiviral medicine and will not treat HIV or AIDS. Cobicistat is given only to help increase your blood levels of atazanavir or darunavir.

When given with atazanavir, cobicistat is for use in adults and children weighing at least 77 pounds (35 kilograms). When given with darunavir, cobicistat is for use in adults and children weighing at least 88 pounds (40 kilograms).

Cobicistat may also be used for purposes not listed in this medication guide.

Cobicistat is not a complete treatment and must be used in combination only with atazanavir or darunavir.

Tell your doctor about all your current medicines and any you start or stop using. Many drugs can interact with cobicistat and cause dangerous effects that could lead to death.

Cobicistat comes as a tablet to take by mouth. It is usually taken with food once a day along with atazanavir or darunavir. Take cobicistat with atazanavir or darunavir at around the same time 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 cobicistat exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

It is important to always take cobicistat at the same time as atazanavir or darunavir.

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.

Cobicistat is usually taken once per day with atazanavir or darunavir.

Take your HIV medicines with food at the same time each day to be sure you do not miss a dose.

If you take cobicistat with atazanavir and you also take medicine to reduce stomach acid, follow these recommendations unless your doctor tells you otherwise:

• If you take an antacid, take it at least 2 hours before or 2 hours after you take cobicistat and atazanavir.

• If you take a medicine such as cimetidine, ranitidine, Tagamet, Axid, Zantac, Pepcid, and others: Take the stomach medicine at the same time you take cobicistat and atazanavir; or wait at least 10 hours after taking the stomach medicine to take your cobicistat and atazanavir doses.

• If you take a proton pump inhibitor such as omeprazole, esomeprazole, Nexium, Prevacid, Prilosec, Protonix: Wait at least 12 hours after taking the stomach medicine to take your cobicistat and atazanavir doses.

You will need frequent medical tests.

Use all HIV medications as directed and read all medication guides you receive. Do not change your dose or dosing schedule without your doctor's advice. Every person with HIV should remain under the care of a doctor.

Store in the original container at room temperature, away from moisture and heat. Keep the bottle tightly closed when not in use.

Cobicistat is not a complete treatment and must be used in combination only with atazanavir or darunavir. You should not take cobicistat with any other antiviral medicines that your doctor has not prescribed.

You should not take cobicistat if you are allergic to it.

Many drugs can interact and cause dangerous effects that could lead to death. Some drugs should not be used together.

You should not take cobicistat with atazanavir if you also take:

• indinavir;

• irinotecan;

• nevirapine; or

• birth control pills that contain drospirenone and ethinyl estradiol (Beyaz, Sayfral, Yasmin, Yaz).

You should not take cobicistat with atazanavir or darunavir if you also take:

• alfuzosin;

• cisapride;

• colchicine;

• dronedarone;

• oral midazolam, or triazolam;

• ranolazine;

• rifampin;

• sildenafil (Revatio, for treating pulmonary arterial hypertension);

• St. John's wort;

• antipsychotic medicine--lurasidone, pimozide;

• cholesterol medication--lomitapide, lovastatin, simvastatin;

• ergot medicine--dihydroergotamine, ergotamine, methylergonovine; or

• seizure medication--carbamazepine, phenobarbital, phenytoin.

You may not be able to take cobicistat if you also take:

• darunavir 600 milligrams twice daily; or

• certain other antiviral medicines--fosamprenavir, saquinavir, or tipranavir.

Tell your doctor if you have ever had:

• liver disease; or

• kidney disease, especially if you also take tenofovir.

Cobicistat may not work as well if you take it during pregnancy. Do not start taking the medicine if you are pregnant. Tell your doctor right away if you become pregnant.

If you plan to get pregnant, ask your doctor for another antiviral medicine to use during pregnancy. Use all medications properly to control your infection. HIV can be passed to your baby if the virus is not controlled during pregnancy. Your name may be listed on a registry to track any effects of antiviral medicine on the baby.

If you do not plan to get pregnant, ask your doctor about using a non-hormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy. Cobicistat can increase certain side effects when taken with hormonal birth control (pills, injections, implants, skin patches, vaginal rings).

Women with HIV or AIDS should not breastfeed a baby. Even if your baby is born without HIV, the virus may be passed to the baby in your breast milk.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Get your prescription refilled before you run out of medicine completely.

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.

Using cobicistat will not prevent your disease from spreading. Do not have unprotected sex or share razors or toothbrushes. Talk with your doctor about safe ways to prevent HIV transmission during sex. Sharing drug or medicine needles is never safe, even for a healthy person.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Cobicistat may cause serious side effects. Call your doctor at once if you have:

• kidney problems--little or no urination, swelling in your feet or ankles, feeling tired or short of breath; or

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

Common side effects of cobicistat may include:

• nausea;

• jaundice; or

• rash.

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.

When you start or stop taking cobicistat, your doctor may need to adjust the doses of any other medicines you take on a regular basis.

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

Tell your doctor about all your current antiviral medicines.

Many drugs can affect cobicistat, and some drugs should not be used at the same time. Tell your doctor about all your current medicines and any medicine you start or stop using. 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 and the laboratory. Your doctor will order certain lab tests before and during your treatment to check your body's response to cobicistat.

Keep a supply of medication on hand. Do not wait until you run out of medication to refill your prescription.

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

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.