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 . If you are concerned about side effects, discuss the risks and benefits of with your doctor.

The following side effects have been reported by at least 1% of people taking . 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.

• abdominal pain
• headache
• nausea or vomiting (infrequent)
• rash

Although most of these 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:

• nausea or vomiting (frequent)
• rapid heartbeat
• signs of gallstones (e.g., nausea, vomiting, severe abdominal pain)
• 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 an autoimmune disorder (e.g., Fever, unusual joint or muscle pain, rash, fatigue)
• 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 irregular heartbeat (e.g., chest pain, dizziness, rapid, pounding heartbeat, shortness of breath)
• weight loss

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

• signs of an allergic reaction (shortness of breath or difficulty breathing; Hives; swelling of the eyes, mouth, lips, or throat)
• signs of Kidney Stones (pain in your side, blood in urine, pain when urinating)
• symptoms of a condition called lactic acidosis (unusual weakness or tiredness, unusual muscle pain, stomach pain with nausea and vomiting, feeling cold especially in arms and legs, dizziness or lightheadedness, and fast or irregular heartbeat)

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 .

150 mg
Each hard-shell gelatin capsule with a greenish-blue opaque cap and blue opaque body, axially printed with "MYLAN" over "AR150" in black ink on both the cap and body, and filled with white-to-pale-yellow powder, contains atazanavir sulfate equivalent to 150 mg of atazanavir. Nonmedicinal ingredients: crospovidone, lactose monohydrate, magnesium stearate; capsule shell: D&C Red 28, FD&C Blue No. 1, FD&C Red No. 3, gelatin, iron oxide yellow, and titanium dioxide; black imprinting ink: black iron oxide, potassium hydroxide, propylene glycol, shellac, and strong ammonia solution. 

200 mg 
Each hard-shell gelatin capsule with a blue opaque cap and blue opaque body, axially printed with "MYLAN" over "ARC200" in black ink on both the cap and body, and filled with white-to-pale-yellow powder, contains atazanavir sulfate equivalent to 200 mg of atazanavir. Nonmedicinal ingredients: crospovidone, lactose monohydrate, magnesium stearate; capsule shell: FD&C Blue No. 1, FD&C Red No. 3, gelatin, and titanium dioxide; black imprinting ink: black iron oxide, potassium hydroxide, propylene glycol, shellac, and strong ammonia solution. 

300 mg
Each hard-shell gelatin capsule with a red opaque cap and greenish-blue opaque body, axially printed with "MYLAN" over "AR300" in black ink on both the cap and body, and filled with white-to-pale-yellow powder, contains atazanavir sulfate equivalent to 300 mg of atazanavir. Nonmedicinal ingredients: crospovidone, lactose monohydrate, magnesium stearate; capsule shell: FD&C Blue No. 1, FD&C Red No. 3, iron oxide red, iron oxide yellow, gelatin, and titanium dioxide; black imprinting ink: black iron oxide, potassium hydroxide, propylene glycol, shellac, and strong ammonia solution.

Do not take atazanavir if you:

• are allergic to atazanavir or any ingredients of the medication
• are taking any of the following medications:
• Alfuzosin
• Apixaban (if also taking ritonavir)
• ergot-type medications (i.e., Dihydroergotamine, ergonovine, ergotamine, or methylergonovine)
• Hepatitis C direct acting antivirals (e.g., elbasvir, grazoprevir, glecaprevir, pibrentasvir)
• indinavir
• Irinotecan
• Lovastatin
• Lomitapide
• Lurasidone (if also taking ritonavir)
• nevirapine
• Pimozide
• Quetiapine
• quinidine
• rifampin
• Rivaroxaban (if also taking ritonavir)
• Sildenafil (when used for pulmonary arterial hypertension)
• Simvastatin
• St. John's wort
• Triazolam

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

• Alitretinoin
• alpha-blockers (e.g., alfuzosin, Doxazosin, Silodosin, Tamsulosin)
• Amiodarone
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
• anticancer medications (e.g., Cabazitaxel, Docetaxel, Doxorubicin, Etoposide, Ifosfamide, irinotecan, Vincristine)
• antipsychotics (e.g., Clozapine, Haloperidol, lurasidone, Olanzapine, pimozide, quetiapine, Risperidone)
• Apalutamide
• apixaban
• Aprepitant
• "azole" antifungals (e.g., fluconazole, itraconazole, ketoconazole, Voriconazole)
• benzodiazepines (e.g., Chlordiazepoxide, Clonazepam, Diazepam, Lorazepam, midazolam, triazolam)
• birth control pills (estrogen and progestin)
• Bosentan
• Bromocriptine
• Buprenorphine
• Buspirone
• calcifediol
• Calcitriol
• calcium channel blockers (e.g., diltiazem, Felodipine, nicardipine, Nifedipine, verapamil)
• cannabis
• Cobicistat
• Colchicine
• conivaptan
• corticosteroids (e.g., Dexamethasone, fluticasone, Hydrocortisone, Prednisone)
• Cyclosporine
• dabigatran
• Dapsone
• Darifenacin
• Deferasirox
• Degarelix
• diabetes medications (e.g., Canagliflozin, Glyburide, insulin, Linagliptin, Metformin, Repaglinide, Rosiglitazone, Sitagliptin)
• Disopyramide
• Domperidone
• Dronedarone
• Dutasteride
• Elagolix
• Eliglustat
• Eluxadoline
• enfuvirtide
• Enzalutamide
• Eplerenone
• ergotamine or ergot-type medications (e.g., dihydroergotamine, ergonovine, or methylergonovine)
• estrogens (e.g., conjugated estrogen, Estradiol, ethinyl estradiol)
• Everolimus
• Flibanserin
• Galantamine
• grapefruit juice
• Guanfacine
• H2 antagonists (e.g., Famotidine, Ranitidine)
• hepatitis C antivirals (e.g., glecaprevir and pibrentasvir, grazoprevir, ledipasvir, sofosbuvir)
• HIV integrase inhibitors (e.g., bictegravir, dolutegravir, elvitegravir, raltegravir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., efavirenz, etravirine, nevirapine)
• other HIV protease inhibitors (e.g., indinavir, ritonavir, saquinavir)
• HIV nucleoside reverse transcriptase inhibitors (NRTIs; e.g., abacavir, didanosine, lamivudine, tenofovir, zidovudine)
• Ivabradine
• Ivacaftor
• lidocaine
• lomitapide
• lumacaftor and ivacaftor
• Macitentan
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• maraviroc
• Mefloquine
• Methadone
• mifepristone
• Minocycline
• Minoxidil
• Mirtazapine
• Modafinil
• Naloxegol
• narcotics (e.g., Codeine, Fentanyl, Morphine, Oxycodone)
• nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
• Orlistat
• Oxybutynin
• phosphodiesterase (PDE 5) inhibitors (e.g., sildenafil, Tadalafil, Vardenafil)
• Pimecrolimus
• praziquantel
• progestins (e.g., Dienogest, Levonorgestrel, medroxyprogesterone, Norethindrone)
• Propafenone
• protein kinase inhibitors (e.g., Bosutinib, imatinib, Nilotinib)
• proton pump inhibitors (e.g., Lansoprazole, Omeprazole)
• quinidine
• quinine
• rifabutin
• rifampin
• rilpivirine
• Riociguat
• rivaroxaban
• Romidepsin
• rupatadine
• St. John's wort
• salmeterol
• Sarilumab
• seizure medications (e.g., Carbamazepine, Clobazam, Levetiracetam, Phenobarbital, Phenytoin, primidone, Topiramate, Valproic acid, zonisamide)
• siltuximab
• Sirolimus
• Solifenacin
• "statin" anti-cholesterol medications (e.g., Atorvastatin, lovastatin, simvastatin)
• Tacrolimus
• Tamoxifen
• Ticagrelor
• Tocilizumab
• Tolterodine
• Tolvaptan
• Tramadol
• Trazodone
• tricyclic antidepressants (e.g., Amitriptyline, Desipramine, Imipramine, Nortriptyline)
• "triptan" migraine medications (e.g., Almotriptan, Eletriptan)
• Ulipristal
• Vilazodone
• Warfarin
• Zolpidem
• 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 . 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.

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 .

Diabetes: Some people taking protease inhibitor medications such as atazanavir have developed diabetes during treatment, and some people who already had diabetes noticed that their diabetes became worse during treatment. If you have diabetes, discuss with your doctor how may affect your medical condition, how your medical condition may affect the dosing and effectiveness of , and whether any special monitoring is needed.

Gallstones: Atazanavir can cause gallstones, concentrations of the bile that is produced by the liver. If you experience symptoms of gallstones, such as persistent severe pain on the right side of your abdomen, nausea and vomiting, or pain between the shoulder blades or under the right shoulder, contact your doctor as soon as possible.

Heart effects: Atazanavir can affect heart rhythm (heartbeat) for some people. If you have problems with the electrical conduction system of your heart (e.g., first-, second-, and third-degree AV block) or are taking medications that affect the electrical conduction system of the heart (e.g., Diltiazem, Verapamil), discuss with your doctor how may affect your medical condition, how your medical condition may affect the dosing and effectiveness of , and whether any special monitoring is needed.

Hemophilia: People with hemophilia A or B may be at an increased risk of bleeding while taking atazanavir. If you have a bleeding condition, discuss with your doctor how may affect your medical condition, how your medical condition may affect the dosing and effectiveness of , and whether any special monitoring is needed.

Immune reconstitution inflammatory syndrome: When you start taking HIV medications such as atazanavir, your immune system may get stronger and start to fight other infections that have been hidden in your body (e.g., pneumonia, herpes, or Tuberculosis). Contact your doctor if you develop any new symptoms after starting HIV medications such as atazanavir.

Kidney function: Chronic Kidney Disease has been reported with the use of atazanavir. If you have a history of kidney disease, discuss with your doctor how may affect your medical condition, how your medical condition may affect the dosing and effectiveness of , and whether any special monitoring is needed.

Kidney stones: Some people taking atazanavir have developed kidney stones. If you develop signs or symptoms of kidney stones (e.g., pain in your side, blood in your urine, or pain when you urinate), contact your doctor immediately.

Lactic acidosis: People taking atazanavir in combination with some other HIV medications (e.g., abacavir, didanosine, lamivudine, and zidovudine) may be at risk of a serious condition called lactic acidosis. Lactic acidosis is a buildup of lactic acid in the blood. If you notice any of the symptoms of lactic acidosis, such as difficulty breathing, abdominal pain, muscle weakness, nausea, and vomiting, stop taking and contact your doctor immediately.

Lactose:  contains lactose. If you have hereditary problems of galactose intolerance, lactase deficiency, or glucose-galactose malabsorption, talk to your doctor about whether is appropriate for you.

Liver function: Liver disease or reduced liver function may cause to build up in the body, causing side effects. can also cause liver failure and reduced liver function. People with hepatitis B or C, or liver disease, may experience worsening of their liver disease symptoms while taking . Your doctor will monitor your liver function while you are taking atazanavir. Report any 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) to your doctor immediately. People with severe liver disease should not take .

Other medications: Atazanavir may interact with a number of medications, which may mean a change in how you take (see "What medications can interact with ?"). Tell your doctor about all the medications that you are taking. Certain medications should not be taken with atazanavir at all (see "Who should NOT take ?").

Atazanavir should never be used alone; it should always be used in combination with other HIV medications.

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

Breast-feeding:  passes into breast milk. If you are breast-feeding and are taking atazanavir, it may affect your baby. Breast-feeding is not recommended for HIV-positive women since the virus can be transmitted through breast milk.

Children and adolescents: The safety and effectiveness of using have not been established for children between 3 months and 6 years of age. Do not give to children younger than 3 months as it can cause a form of brain damage known as kernicterus.

Atazanavir belongs to the class of medications known as azapeptide HIV-1 protease inhibitors. It is used in combination with other medications to treat human immunodeficiency virus 1 (HIV-1) infection. HIV is the virus responsible for acquired immunodeficiency syndrome (AIDS). HIV infection destroys CD4 (T) cells, which are important to the immune system. The immune system helps fight infections.

Atazanavir reduces the amount of HIV in the blood by interfering with the enzyme protease that the HIV virus needs in order to multiply. Atazanavir may also help the immune system by increasing the number of CD4 (T) cells in the body.

does not cure HIV infection or AIDS and does not reduce the risk of passing HIV on to others through sexual contact or blood contamination.

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

Your doctor may have suggested 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 , speak to your doctor. Do not stop taking without consulting your doctor.

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