Cimetidine and Azelastine Nasal Spray: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Cimetidine
Azelastine Nasal Spray
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of azelastine adverse effects (increased somnolence, headache, bitter taste)
Interaction Deep Dive
Concurrent use of cimetidine (400 mg twice daily) and oral azelastine (4 mg twice daily) increased the mean Cmax and area under the concentration-time curve (AUC) of azelastine by approximately 65% in normal volunteers1.
Why it happens (mechanism)
Inhibition of azelastine metabolism
Common questions
Can I take Cimetidine and Azelastine Nasal Spray together?
An increased risk of azelastine adverse effects (increased somnolence, headache, bitter taste) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cimetidine and Azelastine Nasal Spray interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Cimetidine or Azelastine Nasal Spray need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Product Information: Astelin(R), azelastine. Wallace Laboratories, Cranbury, NJ, 2000. DailyMed
Keep reading about Cimetidine
Keep reading about Azelastine Nasal Spray
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist