SIDE EFFECTS: Nausea may occur. If this persists or worsens, tell your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she 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 trouble breathing/swallowing/moving your eyes, drooping face, paralysis, trouble speaking). Tell your doctor right away if you have any serious side effects, including: persistent nausea/vomiting, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine. 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.

PRECAUTIONS: Before taking cobicistat, tell your doctor or pharmacist if you are allergic to it; 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: kidney disease. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). During pregnancy, this medication should be used only when clearly needed. Treatment can lower the risk of passing HIV infection to your baby, and cobicistat may be part of that treatment. Discuss the risks and benefits with your doctor. It is unknown if this medication passes into breast milk. Because breast milk can transmit HIV, do not breast-feed.

DRUG INTERACTIONS: 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: elvitegravir, 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, tamsulosin), certain benzodiazepines (such as midazolam, triazolam), dronedarone, ergot alkaloids (such as dihydroergotamine, ergotamine), quinidine, pimozide, salmeterol, simeprevir, certain drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as avanafil, sildenafil), certain "statin" cholesterol drugs (lovastatin, simvastatin), among others. Other medications can affect the removal of cobicistat from your body, which may affect how cobicistat works. Examples include certain drugs used to treat seizures (such as carbamazepine, phenobarbital, phenytoin, primidone), enzalutamide, certain HIV NNRTI drugs (such as efavirenz, etravirine, nevirapine), rifamycins (such as rifabutin, rifampin), St. John's wort, among others. This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Talk to your doctor about additional or alternative reliable forms of birth control, and always use an effective barrier method (latex or polyurethane condoms/dental dams) during all sexual activity to decrease the risk of spreading HIV to others. Tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your hormonal birth control is not working well. Do not take this medication with other products that contain cobicistat.

OVERDOSE: 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 their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.