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.

Side Effects Of Cobicistat

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.

Warnings & Precautions

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: atorvastatin (Lipitor, in Caduet); benzodiazepines such as diazepam (Valium) and midazolam given intravenously (into a vein); beta blockers such as carvedilol (Coreg), metoprolol (Lopressor), and timolol; boceprevir (Victrelis) (not available in the U.S.); bosentan (Tracleer); budesonide (Entocort, Pulmicort, , Uceris); 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); dasatinib (Sprycel); dexamethasone; efavirenz (Sustiva, in Atripla); erythromycin (E.E.S, Erytab, others); etravirine (Intelence); fentanyl (Abstral, Actiq, Fentora, others); fluticasone (Flonase, Flovent, in Advair); 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) 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); voriconazole (Vfend); and warfarin (Coumadin, Jantoven). 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.

Dosage Of Cobicistat

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.


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.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.