Atazanavir: what it is and how to use it

Atazanavir is an HIV medicine from the protease inhibitor class. People take it to lower the amount of HIV in the blood and help keep the immune system working. It’s often used with a booster (ritonavir or cobicistat) and with other antiretrovirals. Here’s a clear, practical look at what you need to know if you or someone you care for is prescribed atazanavir.

How atazanavir works and common dosing

Atazanavir blocks the HIV protease enzyme so new virus particles can't mature. Typical adult dosing is 300 mg atazanavir plus 100 mg ritonavir once daily with food. Sometimes cobicistat (150 mg) is used as the booster instead of ritonavir. Unboosted atazanavir (400 mg once daily) is less common and usually only used in specific situations.

Always take atazanavir with food — it raises absorption. If you miss a dose, follow your doctor’s instructions, but don’t double up unless told to. Keep pills in their original container at room temperature and away from moisture.

Side effects, interactions and monitoring

Expect some side effects but most are manageable. A common effect is indirect hyperbilirubinemia — that can cause yellowing of the skin or eyes without liver damage. Other possible effects: nausea, headache, rash, and rarely PR-interval prolongation (a heart rhythm change). Atazanavir tends to have a smaller impact on cholesterol than some other protease inhibitors.

Drug interactions matter a lot. Atazanavir is broken down by CYP3A enzymes, so many medicines raise or lower its levels. Avoid or adjust doses of strong inducers (like rifampin, some anticonvulsants) and strong inhibitors. Acid-reducing drugs are a special case: proton pump inhibitors (PPIs) usually shouldn’t be used with atazanavir, and H2 blockers or antacids must be spaced out (take atazanavir with food and avoid antacids within a few hours). Tell your provider about all prescriptions, OTC drugs, and supplements.

Your clinic will monitor viral load and CD4 counts, bilirubin and liver tests, and sometimes ECG if you have a heart condition. Check kidney function if you develop symptoms like flank pain or blood in urine, since stones can occur rarely.

Pregnancy and breastfeeding: atazanavir is used in pregnancy but needs close monitoring. Drug levels can change during pregnancy, so clinicians may adjust dosing or choose alternatives. If you’re pregnant, planning pregnancy, or breastfeeding, discuss options with your HIV care team.

Why adherence matters: skipping doses can lead to resistance and limit future treatment choices. Use alarms, pill boxes, or a partner reminder to keep a steady routine. If side effects make it hard to stay on the drug, contact your clinician — there are other regimens that may work better for you.

If you notice jaundice, new heart symptoms, severe rash, trouble breathing, or signs of infection, get medical help right away. For routine questions — timing with antacids, pregnancy concerns, or switching boosters — your HIV clinic or pharmacist can give quick, practical answers tailored to you.