This combination product contains two medications: atazanavir and cobicistat. These two medications are used in combination with other medications to reduce the amount of human immunodeficiency virus (HIV) in the blood.

Atazanavir is a protease inhibitor and works by blocking an enzyme called protease, which the virus needs to multiply. Cobicistat slows down the speed at which the body gets rid of atazanavir. It is included in this medication to increase the length of time that the body is exposed to atazanavir with each dose.

This medication does not cure AIDS and does not reduce the risk of passing HIV to others through sexual contact or blood contamination. It is used in combination with other anti-HIV medications to slow further growth or reproduction of HIV. It also seems to slow down the destruction of the immune system. This may help to delay the development of problems such as infections related to AIDS or HIV disease.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended adult dose of atazanavir - cobicistat is 1 tablet taken once daily with food. It should be taken at approximately the same time each day. The tablet should be swallowed whole and not broken, crushed or chewed.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor.

If you miss a dose, and it is less than 12 hours since the missed dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not take this medication if you:

• are allergic to atazanavir, cobicistat or any ingredients of the medication
• are taking certain other medications, including but not limited to
• alfuzosin
• amiodarone
• ergot derivatives (e.g., dihydroergotamine, ergonovine, ergotamine, methylergonovine)
• indinavir
• irinotecan
• lidocaine
• lovastatin
• midazolam
• pimozide
• quinidine
• rifampin
• ritonavir
• salmeterol
• sildenafil (for the treatment of pulmonary arterial hypertension)
• simvastatin
• St. John's wort
• triazolam

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• rash

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• fast or slow heartbeat
• frequent nausea, vomiting and stomach pain
• gall bladder problems (e.g., abdominal pain, yellowing of the skin, nausea, vomiting, fever, chills)
• irregular heartbeat
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• symptoms of kidney stones (e.g., pain in the side, blood in the urine and painful urination)
• unexpected symptoms (e.g., fever, joint, muscle pain, redness, rash, swelling or fatigue) may be symptoms of infections

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Diabetes: Atazanavir - cobicistat may cause a loss of blood glucose control, and glucose tolerance may change. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Fat redistribution: Over time, this medication may change how fat is distributed in your body and may change your body shape. You may notice increased fat in the upper back and neck, breast, around the back, chest, and stomach area; or loss of fat from the legs, arms, and face. The long-term effects of this are not known.

Heart rhythm: Atazanavir - cobicistat can cause changes to the normal rhythm of the heart, which can cause fainting, seizures and, in severe cases, sudden death. If you are at risk for heart rhythm problems (e.g., if you have heart failure, angina, or low potassium or magnesium levels), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Hemophilia: People with hemophilia type A and B, which are blood-clotting disorders, have experienced increased bleeding and bruising when taking protease inhibitors such as atazanavir. If you have hemophilia, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Immune reconstitution syndrome: This medication may cause immune reconstitution syndrome, where signs and symptoms of inflammation from previous infections appear. These symptoms occur soon after starting anti-HIV medication and can vary. They are thought to occur as a result of the immune system improving and being able to fight infections that have been present without symptoms (such as pneumonia, herpes or tuberculosis). Report any new symptoms to your doctor immediately.

Kidney function: This medication has been reported to cause changes in kidney function. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication. People with severe liver disease should not take atazanavir - cobicistat.

There have been reports of serious liver problems while taking atazanavir. People with liver problems (including hepatitis B or hepatitis C infection) are at a greater risk of experiencing serious liver problems while taking this medication. If you experience symptoms of liver problems (e.g., abdominal pain, persistent vomiting, feeling unwell, fever, itching, yellowing of the skin and eyes, dark urine), contact your doctor immediately.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if atazanavir - cobicistat passes into breast milk. Women who have HIV infection are cautioned against breast-feeding because of the risk of passing HIV to a baby who does not have the infection.

Children: The safety and effectiveness of using this medication have not been established for children.

There may be an interaction between atazanavir - cobicistat and any of the following:

• abiraterone acetate
• aliskiren
• alitretinoin
• almotriptan
• alpha blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
• amiodarone
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
• anti-cancer medications (e.g., cabazitaxel, docetaxel; doxorubicin; etoposide, ifosfamide, irinotecan, vincristine)
• antihistamines
• antipsychotic medications (e.g., aripiprazole, chlorpromazine, haloperidol, quetiapine, risperidone)
• apixaban
• aprepitant
• atomoxetine
• avanafil
• “azole” antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• bicalutamide
• benzodiazepines (e.g., chlordiazepoxide, clonazepam, diazepam, lorazepam)
• beta-adrenergic blockers (e.g., carvedilol, metoprolol, propranolol, timolol, sotalol)
• birth control pills
• bosentan
• brinzolamide
• bromocriptine
• buprenorphine
• buspirone
• busulfan
• calcitriol
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• captopril
• carbamazepine
• chloroquine
• cilostazol
• cisapride
• colchicine
• conivaptan
• inhaled corticosteroids (e.g., budesonide, ciclesonide, fluticasone)
• oral corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
• cyclosporine
• dapsone
• darifenacin
• deferasirox
• degarelix
• diabetes medications (e.g., chlorpropamide, glipizide, glyburide, insulin, metformin, nateglinide, rosiglitazone)
• digoxin
• disopyramide
• disulfiram
• dofetilide
• domperidone
• doxepin
• dronedarone
• dutasteride
• eletriptan
• enzalutamide
• eplerenone
• ergot alkaloids (e.g., dihydroergotamine, ergonovine,  ergotamine, methylergonovine)
• estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
• ethosuximide
• everolimus
• flecainide
• flutamide
• “gliptin” diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
• grapefruit juice
• guanfacine
• H2 antagonists (e.g., famotidine, ranitidine)
• hepatitis C antiviral medications (e.g., boceprevir, elbasvir, ledipasvir, sofosbuvir, telaprevir)
• hepatitis C antiviral combinations (e.g., ombitasvir - paritaprevir - ritonavir - dasabuvir, ombitasvir - paritaprevir - ritonavir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delaviridine, efavirenz, etravirine, nevirapine)
• HIV nucleoside reverse transcriptase inhibitors (NRTIs; e.g., abacavir, didanosine, lamivudine, tenofovir, zidovudine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• hydrocodone
• lidocaine
• lomitapide
• loperamide
• losartan
• lurasidone
• macitentan
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• maraviroc
• mefloquine
• meperidine
• mestranol
• methadone
• methamphetamine
• methotrexate
• metronidazole
• mexiletine
• mifepristone
• minocycline
• minoxidil
• mirtazapine
• modafinil
• montelukast
• naloxegol
• nefazodone
• nitrates (e.g., isosorbide dinitrate,  isosorbide mononitrate)
• norfloxacin
• oxybutynin
• oxycodone
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pimozide
• prasugrel
• praziquantel
• primaquine
• procainamide
• progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
• propafenone
• protein kinase inhbitors (e.g., dabrafenib, dasatinib, imatinib, lapatinib, pazopanib, sunitinib)
• proton pump inhibitors (e.g., lansoprazole, omeprazole)
• prucalopride
• quinidine
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, ofloxacin, sparfloxacin)
• repaglinide
• rifabutin
• rifampin
• rilpivirine
• riociguat
• rivaroxaban
• romidepsin
• St. John's wort
• salmeterol
• seizure medications (e.g., carbamazepine, clobazam, ethosuximide, levetiracetam, phenobarbital, phenytoin, primidone, topiramate, valproic acid, zonisamide)
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
• serotonin antagonists (anti-emetic medications; e.g., granisetron, ondansetron)
• serotonin-norepinephrine reuptake inhibitors (SNRIs; e.g., duloxetine, venlafaxine)
• sirolimus
• solifenacin
• "statin" anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
• stiripentol
• tacrolimus
• tamoxifen
• temsirolimus
• tetrabenazine
• tetracycline
• theophylline
• ticagrelor
• ticlopidine
• tizanidine
• tolterodine
• tolvaptan
• tramadol
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
• ulipristal
• zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.