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(koe bik' i stat)

Brand Name(s): Tybost®, Evotaz® (as a combination product containing Atazanavir, Cobicistat), Prezcobix® (as a combination product containing Cobicistat, Darunavir)

WHY is this medicine prescribed?

Cobicistat is used to increase the amounts of atazanavir (Reyataz, in Evotaz ) in adults and children weighing at least 77 pounds (35 kg) or darunavir (Prezista, in Prezcobix ) in adults and children weighing at least 88 pounds (40 kg) in the blood when these medications are used to treat human immunodeficiency virus (HIV). Cobicistat is in a class of medications called cytochrome P450 3A (CYP3A) inhibitors. It works by increasing the amount of atazanavir or darunavir in the body so that they can have a greater effect.

Are there OTHER USES for this medicine?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

HOW should this medicine be used?

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.

What SPECIAL PRECAUTIONS should I follow?

Before taking cobicistat,

  • tell your doctor and pharmacist if you are allergic to cobicistat, any other medications, or any of the ingredients in cobicistat tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor if you are taking any of the following medications: alfuzosin (Uroxatral); carbamazepine (Carbatrol, Epitol, Equetro, Tegretol); cisapride (Propulsid) (not available in the U.S.); colchicine (Colcrys, Mitigare, in Col-Probenecid); dronedarone (Multaq); ergot medications such as dihydroergotamine (D.H.E. 45, Migranal), ergotamine (Ergomar, in Cafergot, in Migergot), and methylergonovine (Methergine); lomitapide (Juxtapid); lovastatin (Altoprev); lurasidone (Latuda); midazolam (Versed) by mouth; phenobarbital; phenytoin (Dilantin, Phenytek); pimozide (Orap); ranolazine (Ranexa); rifampin (Rimactane, Rifadin, in Rifamate, in Rifater); sildenafil (only Revatio brand used for lung disease); simvastatin (Flolipid, Zocor); St. John's wort; or triazolam (Halcion). If you are taking atazanavir along with cobicistat, tell your doctor if you are taking drospirenone and ethinyl estradiol (certain oral contraceptives such as Beyaz, Safyral, Yasmin, Yaz, others); indinavir (Crixivan), irinotecan (Camptosar), or nevirapine (Viramune). Your doctor will probably tell you not to take cobicistat if you are taking any of these medications.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: anticoagulants ('blood thinners') such as apixaban (Eliquis), betrixaban (Bevyxxa), dabigatran (Pradaxa), edoxaban (Savaysa), rivaroxaban (Xarelto), and warfarin (Coumadin, Jantoven); antiplatelet medications such as clopidogrel (Plavix) and ticagrelor (Brilinta); atorvastatin (Lipitor, in Caduet); benzodiazepines such as diazepam (Valium), estazolam, midazolam given intravenously (into a vein), and zolpidem (Ambien, Edluar, Intermezzo); beta blockers such as carvedilol (Coreg), metoprolol (Lopressor), and timolol; boceprevir (Victrelis) (not available in the U.S.); bosentan (Tracleer); buprenorphine (Belbuca, Butrans, Probuphine); buprenorphine and naloxone (Suboxone, Zubsolv); buspirone; calcium channel blockers such as amlodipine (Norvasc), diltiazem (Cardizem, Cartia, Tiazac, others), felodipine, nifedipine (Adalat, Afeditab, Procardia), and verapamil (Calan, Verelan, others); clarithromycin (Biaxin, in PrevPac); corticosteroids such as beclomethasone (Beconase AQ), budesonide (Rhinocort Aqua), ciclesonide (Omnaris), dexamethasone (Decadron), fluticasone (Flonase, Flovent), methylprednisolone (Medrol), momentasone (Flonase), and triamcinolone (Nasacort AQ); dasatinib (Sprycel); efavirenz (Sustiva, in Atripla); erythromycin (E.E.S, Erytab, others); etravirine (Intelence); fentanyl (Abstral, Actiq, Fentora, others); itraconazole (Onmel, Sporanox); ketoconazole; medications for depression such as amitriptyline, desipramine (Norpramin), imipramine (Tofranil), nortriptyline (Pamelor), paroxetine (Brisdelle, Paxil, Pexeva), and trazodone; medications for irregular heartbeat such as amiodarone (Cordarone, Nexterone, Pacerone), digoxin (Lanoxin), disopyramide (Norpace), flecainide, mexiletine, propafenone (Rythmol), and quinidine (in Nuedexta); medications for seizures such as clonazepam (Klonopin), eslicarbazepine (Aptiom), and oxcarbazepine (Trileptal); medications that suppress the immune system such as cyclosporine (Gengraf, Neoral, Sandimmune), everolimus (Afinitor, Zortress), sirolimus (Rapamune), and tacrolimus (Astagraf, Envarsus XR, Prograf); lopinavir (in Kaletra); maraviroc (Selzentry); methadone (Dolophine, Methadose); nilotinib (Tasigna); oral contraceptives (birth control pills); perphenazine; certain phosphodiesterase (PDE5) inhibitors such as avanafil (Stendra), sildenafil (Viagra), tadalafil (Adcirca, Cialis), and vardenafil (Levitra); quetiapine (Seroquel); rifabutin (Mycobutin); risperidone (Risperdal); ritonavir (Norvir, in Kaletra); rivaroxaban (Xarelto); rosuvastatin; salmeterol (Serevent, in Advair); simeprevir (Olysio); telaprevir (Incivek) (not available in the U.S.); telithromycin (Ketek); tenofovir (Viread, in Atripla, Complera, Truvada, others), thioridazine; tramadol (Conzip, Ultram, in Ultracet); vinblastine; vincristine (Marqibo Kit); and voriconazole (Vfend). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with cobicistat so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • if you are taking cobicistat with atazanavir and you are also taking antacids (Maalox, Mylanta, Tums, others), take them 2 hours before or 2 hours after cobicistat and atazanavir.
  • if you are taking cobicistat with atazanavir and you are also taking a medication for indigestion, heartburn, or ulcers (H2 blockers) such as cimetidine, famotidine (Pepcid, in Duexis), nizatidine (Axid), or ranitidine (Zantac), take them at the same time or at least 10 hours after taking the H2 blocker.
  • if you are taking cobicistat with atazanavir and you are also taking a medication for indigestion, heartburn, or ulcers (proton pump inhibitors) such as esomeprazole (Nexium, in Vimovo), lansoprazole (Prevacid), omeprazole (Prilosec, in Zegerid), pantoprazole (Protonix), or rabeprazole (AcipHex) take them at least 12 hours after taking the proton pump inhibitor.
  • tell your doctor if you have or have ever had kidney or liver disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking cobicistat, call your doctor. You should not breastfeed if you are infected with HIV or if you are taking cobicistat.

What SPECIAL DIETARY instructions should I follow?

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

What should I do IF I FORGET to take a dose?

If your next dose is due in 12 hours or more, take the missed dose as soon as you remember it. However, if the next dose will be taken in less than 12 hours, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

Cobicistat may cause side effects. Tell your doctor if this symptom is severe or does not go away:

  • nausea

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:

  • yellowing of the skin or eyes
  • rash
  • decreased urination

Cobicistat may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about STORAGE and DISPOSAL of this medication?

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.

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 ( for more information if you do not have access to a take-back program.

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What OTHER INFORMATION should I know?

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.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists® represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists® makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists® does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

Pronunciation Guide for Drug Names is used with permission. © 2009. The United States Pharmacopeial Convention. All Rights Reserved.

AHFS® Patient Medication Information™. © Copyright, 2021. The American Society of Health-System Pharmacists®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: November 15, 2020.