Drug interactions
Diphenhydramine + Ephedrine
Severity: Minor
Diphenhydramine and Ephedrine: minor 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
Ephedrine is a stimulant that may partly offset the drowsiness caused by diphenhydramine. Both can cause tachycardia, and the net effect varies between patients, so the interaction is generally of little concern.
What this interaction means in plain words
Diphenhydramine and Ephedrine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Diphenhydramine belongs to Respiratory; Ephedrine belongs to Cardiovascular.
Why it happens
Opposing CNS effects of sympathomimetic stimulation and H1 antagonism, with some overlapping cardiovascular effects.
What to do
No specific action is needed. Monitor heart rate and blood pressure in patients with cardiovascular disease.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Diphenhydramine
Other interactions of Ephedrine
- Ephedrine + Isocarboxazid Contraindicated
- Ephedrine + Phenelzine Contraindicated
- Ephedrine + Procarbazine Contraindicated
- Ephedrine + Rasagiline Contraindicated
- Ephedrine + Selegiline Contraindicated
- Ephedrine + Tranylcypromine Contraindicated
Frequently asked questions
Can I take Diphenhydramine with Ephedrine?
MediHelp rates the interaction as minor. Diphenhydramine and Ephedrine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Ephedrine is a stimulant that may partly offset the drowsiness caused by diphenhydramine. Both can cause tachycardia, and the net effect varies between patients, so the interaction is generally of little concern.
How serious is the interaction between Diphenhydramine and Ephedrine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No specific action is needed. Monitor heart rate and blood pressure in patients with cardiovascular disease.
What other medicines interact with Diphenhydramine?
MediHelp also lists interactions of Diphenhydramine with, for example, Alfentanil, Belladonna and opium, Benzhydrocodone / acetaminophen. The full list is on the Diphenhydramine page.
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