Drug interactions
Atazanavir + Cimetidine
Severity: Major
Atazanavir and Cimetidine: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Atazanavir solubility falls as gastric pH rises, so H2 antagonists such as cimetidine can substantially lower its levels. This risks virologic failure and resistance.
What this interaction means in plain words
Atazanavir and Cimetidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Atazanavir belongs to Anti Virals; Cimetidine belongs to Gastrointestinal Tract.
Why it happens
Increased gastric pH reduces atazanavir dissolution and absorption.
What to do
Give atazanavir at least 2 hours before or 10 hours after the H2 antagonist and keep within labeled maximum H2 antagonist doses. In treatment-experienced patients use atazanavir with ritonavir per labeling.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Atazanavir and Cimetidine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram Major
- Cimetidine + Clozapine Major
Other interactions of Atazanavir
- Alfuzosin + Atazanavir Contraindicated
- Atazanavir + Avanafil Contraindicated
- Atazanavir + Dronedarone Contraindicated
- Atazanavir + Eletriptan Contraindicated
- Atazanavir + Eplerenone Contraindicated
- Atazanavir + Ergotamine Contraindicated
Frequently asked questions
Can I take Atazanavir with Cimetidine?
MediHelp rates the interaction as major. Atazanavir and Cimetidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Atazanavir solubility falls as gastric pH rises, so H2 antagonists such as cimetidine can substantially lower its levels. This risks virologic failure and resistance.
How serious is the interaction between Atazanavir and Cimetidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Give atazanavir at least 2 hours before or 10 hours after the H2 antagonist and keep within labeled maximum H2 antagonist doses. In treatment-experienced patients use atazanavir with ritonavir per labeling.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
