Atazanavir may be marketed under the brand name Reyataz, but generic versions are also available. It is taken in combination with other antiretroviral drugs.

You should not take atazanavir with any of the following medicines: alfuzosin, astemizole, bepridil, cisapride, dihydroergotamine, ergonovine, ergotamine, grazoprevir, lovastatin, methylergonovine, midazolam (oral), pimozide, quetiapine, quinidine, rifampicin, sildenafil (when used to treat pulmonary arterial hypertension), simvastatin, St John’s wort, terfenadine, triazolam.

Drugs that affect the acidity of your stomach and gastrointestinal tract can stop atazanavir being absorbed, meaning it may not be effective at suppressing the virus.

Proton pump inhibitors (indigestion remedies that reduce gastric acid, such as lansoprazole, pantoprazole or omeprazole) should not be taken with atazanavir, unless they have been prescribed by your HIV doctor and the dose of atazanavir is increased. H2 blockers (treatments for ulcers, such as ranitidine (Zantac)) should be taken only once a day, 4 to 12 hours after atazanavir. If atazanavir is taken with tenofovir, you should never take H2-receptor antagonists without speaking to your doctor or pharmacist first. Indigestion remedies or calcium supplements should be taken at least two hours before or one hour after atazanavir. ‘Buffered’ medicines (drugs that have been prepared so they are released slowly into the body) should be taken at least two hours before or one hour after atazanavir. Talk to your HIV doctor or pharmacist before taking any of these drugs with atazanavir, even if you only take them occasionally.

Atazanavir should not be taken with the anti-HIV drug nevirapine or the chemotherapy drug irinotecan.

Taking NNRTI drugs with atazanavir is not recommended.

Kidney stones, severe rash and fever, changes in heart rhythm.

Nausea, diarrhoea, rash, abdominal pain, headache, vomiting, heartburn, tiredness, raised bilirubin levels, sometimes leading to jaundice. Developing some yellowing of the skin and/or eyes (jaundice) is fairly common when taking atazanavir, especially when you first start the drug. Although this can look alarming, it is harmless and does not mean that your liver is damaged, or not working in any way.

Take with food to improve absorption.

The usual adult dose is one 300mg atazanavir capsule taken together with one 100mg ritonavir tablet, once a day. Atazanavir is available as a generic drug so appearances will vary.