This drug is used with other HIV medications to help control HIV infection. It helps to decrease the amount of HIV in your body so your immune system can work better. This lowers your chance of getting HIV complications (such as new infections, cancer) and improves your quality of life. Atazanavir belongs to a class of drugs known as protease inhibitors. Cobicistat is used to increase ("boost") the levels of atazanavir. This helps atazanavir work better.

Atazanavir/cobicistat is not a cure for HIV infection. To decrease your risk of spreading HIV disease to others, continue to take all HIV medications exactly as prescribed by your doctor. Use an effective barrier method (latex or polyurethane condoms/dental dams) during sexual activity as directed by your doctor. Do not share personal items (such as needles/syringes, toothbrushes, and razors) that may have contacted blood or other body fluids. Consult your doctor or pharmacist for more details.

Read the Patient Information Leaflet if available from your pharmacist before you start taking atazanavir/cobicistat and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth with food as directed by your doctor, usually once daily. Since this medication may cause kidney problems, drink plenty of fluids during treatment to lower your risk.

If you are taking antacids or buffered forms of drugs (such as buffered aspirin), take this medication at least 2 hours before or 1 hour after these medications.

It is very important to keep taking this medication (and other HIV medications) exactly as prescribed by your doctor. Do not skip any doses.

For the best effect, take this medication at evenly spaced times. To help you remember, take this medication at the same time every day.

Do not take more or less of this drug than prescribed or stop taking it (or other HIV medicines) even for a short time unless directed to do so by your doctor. Doing so may cause the amount of virus to increase, make the infection more difficult to treat (resistant), or worsen side effects.

Nausea may occur. If this effect lasts or gets worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

As your immune system gets stronger, it can begin to fight off infections you already had, possibly causing disease symptoms to come back. You could also have symptoms if your immune system becomes overactive. This reaction may happen at any time (soon after starting HIV treatment or many months later). Get medical help right away if you have any serious symptoms, including:

• unexplained weight loss
• severe tiredness
• muscle aches/weakness that doesn't go away
• headaches that are severe or don't go away
• joint pain
• numbness/tingling of the hands/feet/arms/legs
• vision changes
• signs of infection (such as fever, chills, swollen lymph nodes, trouble breathing, cough, non-healing skin sores)
• signs of an overactive thyroid (such as irritability, nervousness, heat intolerance, fast/pounding/irregular heartbeat, bulging eyes, unusual growth in the neck/thyroid known as a goiter)
• signs of a certain nerve problem known as Guillain-Barre syndrome (such as unsteadiness, loss of coordination, trouble swallowing/speaking/chewing, trouble moving your eyes)

Tell your doctor right away if you have any serious side effects, including:

• increased thirst/urination
• dizziness
• lightheadedness
• signs of kidney problems (such as pain in side/back/abdomen, painful urination, blood in the urine, change in the amount of urine)
• signs of liver problems (such as nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine)

Get medical help right away if you have any very serious side effects, including:

• signs of a heart attack (such as chest/jaw/left arm pain, shortness of breath, unusual sweating)

Changes in body fat may occur while you are taking this medication (such as increased fat in the upper back and stomach areas, decreased fat in the arms and legs). The cause and long-term effects of these changes are unknown. Discuss the risks and benefits of treatment with your doctor, as well as the possible use of exercise to reduce this side effect.

This medication can commonly cause a rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe reaction. Get medical help right away if you develop any rash.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking atazanavir/cobicistat, tell your doctor or pharmacist if you are allergic to atazanavir; or to cobicistat; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• liver problems (including hepatitis B or C infections)
• kidney problems (including kidney stones)
• heart problems (such as heart rhythm problems, irregular heartbeat, coronary artery disease, heart attack)
• a certain bleeding problem (hemophilia)

This medication may increase the level of cholesterol and fats (triglycerides) in your blood. HIV infection can also cause this effect. This could increase your risk for heart problems such as a heart attack. Discuss the risks and benefits of treatment with your doctor and ways to lower your risk of heart disease. Tell your doctor if you have heart problems, if you smoke, or if you have other conditions that increase your risk of heart disease such as high blood pressure, diabetes, or high cholesterol/triglyceride levels.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This medication is not recommended for use during pregnancy. It may not work well in a pregnant woman. If you become pregnant or think you may be pregnant, tell your doctor right away. Your doctor may change your HIV medications.

Atazanavir passes into breast milk. It is unknown if cobicistat passes into breast milk. Because breast milk may transmit HIV, consult your doctor before breastfeeding.

See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• drospirenone/estradiol
• elvitegravir
• certain medications used to treat chronic hepatitis C (such as elbasvir/grazoprevir, glecaprevir/pibrentasvir)
• indinavir
• orlistat
• ritonavir

This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include certain alpha blockers (such as alfuzosin, silodosin), certain benzodiazepines (midazolam, triazolam), dronedarone, ergot alkaloids (such as dihydroergotamine, ergotamine), irinotecan, lurasidone, pimozide, ranolazine, rivaroxaban, salmeterol, certain drugs to treat erectile dysfunction-ED or pulmonary hypertension (avanafil, sildenafil), certain "statin" cholesterol drugs (lovastatin, simvastatin), among others.

Other medications can affect the removal of this medication from your body, which may affect how this medication works. Examples include apalutamide, lumacaftor, mitotane, certain HIV NNRTIs (such as efavirenz, etravirine, nevirapine), certain rifamycins (such as rifampin, rifapentine), certain drugs used to treat seizures (such as carbamazepine, phenobarbital, phenytoin, primidone), St. John's wort, among others.

Prescription and nonprescription drugs to treat heartburn, indigestion, or ulcers (including H2 blockers such as famotidine, proton pump inhibitors such as lansoprazole/omeprazole) reduce stomach acid and decrease the absorption of atazanavir. This may prevent atazanavir from working well. Ask your doctor or pharmacist how to use these medications safely.

This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use reliable backup birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.

Do not use this medication with other products that contain atazanavir or cobicistat.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: severe dizziness, lightheadedness.

Do not share this medication with others.

Lab and/or medical tests (such as viral load, T-cell counts, liver/kidney function, cholesterol/triglyceride levels, blood sugar levels) should be done before you start taking this medication and while you are taking it. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.