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International Association of Providers of AIDS Care
Revised April 30, 2018

Fact Sheet 447

Atazanavir (Reyataz)



Atazanavir, also called Reyataz, is a drug used as part of antiretroviral therapy (ART).  Atazanavir is a protease inhibitor manufactured by Bristol-Myers Squibb. Atazanavir was approved by the FDA in 2003.  Generic versions have been tentatively approved under PEPFAR (see Fact sheet 925). A combination of atazanavir and cobicistat (see Fact Sheet 455) was approved in 2015 under the name Evotaz.

Protease inhibitors prevent the protease enzyme from working. HIV protease acts like a chemical scissors. It cuts the raw material for HIV into specific pieces needed to build a new virus (see Fact Sheet 106, step 8). Protease inhibitors “gum up” these scissors.



Atazanavir was approved in 2003 as an antiretroviral drug (ARV) for people living with HIV. It can be given to children over 6 years old, and adults.  

There are no absolute rules about when to start ART. You and your health care provider should consider your CD4 cell count, your viral load, any symptoms you are having, and your attitude about taking ART. Fact Sheet 404 has more information about U.S. guidelines for the use of ART.

If you take atazanavir with other ARVs, you can reduce your viral load to extremely low levels, and increase your CD4 cell counts. This should mean staying healthier longer. Although other protease inhibitors lead to increases in blood fats, atazanavir does not. If you have high cholesterol or triglycerides, or other risk factors for heart disease, your health care provider might prescribe atazanavir.



Many new copies of HIV are mutations. They are slightly different from the original virus. Some mutations can keep multiplying even when you are taking an ARV. When this happens, the drug will stop working. This is called “developing resistance” to the drug (see Fact Sheet 126).

Sometimes, if your virus develops resistance to one ARV, it will also be resistant to other ARVs. This is called “cross-resistance.”

Atazanavir provides blood levels that are high enough to control HIV that has already developed some resistance to other protease inhibitors.

Resistance can develop quickly. It is very important to take ARVs according to instructions, on schedule, and not to skip or reduce doses.



Atazanavir is taken once a day with food as capsules. For adults just starting ART, the normal dose is 300 mg plus 100 mg of ritonavir, once a day.

Patients who cannot tolerate ritonavir should take 400 mg of atazanavir. However, this is not recommended for patients who have taken other HIV medications and experienced treatment failure.


Special guidelines for pregnant women were issued in 2011. They should take 300 mg atazanavir with 100 mg of ritonavir. Make sure your health care provider knows if you are taking tenofovir or H2 blockers, a type of antacid, because these can affect atazanavir levels.


Dosing for children at least 6 years old is based on their weight and prior treatment history. For more information see 

Atazanavir is available in capsules of 150 mg, 200 mg and 300 mg, and as a powder in 50 mg packets. Store atazanavir at room temperature, protected from moisture in a tightly sealed container. Do not keep powder that has been mixed with water or food for more than one hour.



Atazanavir can cause high levels of bilirubin, nausea, headache, rash, stomach pain, vomiting, diarrhea, tingling in hands or feet, and depression. Rash may be severe. Patients with severe rash should stop taking atazanavir. Atazanavir may cause changes in heart rhythm. Tell your health care provider if you feel dizzy while taking atazanavir.

Bilirubin is produced by the liver when old red blood cells are broken down. High levels of bilirubin can cause yellow skin or eyes. This is called jaundice. About 10% of people using atazanavir get jaundice.

High bilirubin levels can be a sign of liver damage. However, this is usually not the case for people taking atazanavir because the drug blocks normal removal of bilirubin. 

Atazanavir does not seem to increase the levels of fat or sugar in the blood. That is, triglyceride, cholesterol and glucose levels stay close to normal, unlike with other protease inhibitors. This could be an advantage for people who want to reduce their long-term risk of heart disease. Atazanavir may cause immune reconstitution inflammatory syndrome (IRIS, see Fact Sheet 483).



Atazanavir can interact with other drugs or supplements that you are taking. These interactions can change the amount of each drug in your bloodstream and cause an under- or overdose. New interactions are being identified all the time.

Drugs to watch out for include other ARVs, especially efavirenz or nevirapine), drugs to treat tuberculosis (see Fact Sheet 518), for erectile dysfunction (such as Viagra), irregular heart rhythm (antiarrhythmics), and migraine headaches. Interactions are also possible with several antihistamines (allergy medications), sedatives, drugs to lower cholesterol, and anti-fungal medications. Make sure that your health care provider knows about ALL drugs and supplements you are taking.

  • Atazanavir should not be taken with indinavir (Crixivan; see Fact Sheet 441) due to the increased risk of jaundice.
  • Amprenavir (Agenerase) levels are increased by atazanavir. 
  • Atazanavir can increase levels of hormones contained in birth control pills. Other methods of contraception are recommended.
  • Efavirenz (Sustiva; see Fact Sheet 432) and tenofovir (Viread; see Fact Sheet 419) lower blood levels of atazanavir.
  • There is no interaction between atazanavir and methadone.
  • Watch for signs of excessive sedation if you take atazanavir with buprenorphine.
  • Do not combine atazanavir with midazolam (Versed)
  • Guidelines for taking antacids with atazanavir are complicated. They were updated in 2008. Be sure your health care provider knows if you are taking Prilosec, Zantac, Pepsid or other antacids.
  • The herb St. John's Wort (See Fact Sheet 729) lowers the blood levels of some protease inhibitors. Do not take it with atazanavir.



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