Drug interactions
Diphenhydramine + Mirtazapine
Severity: Moderate
Diphenhydramine and Mirtazapine: moderate 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
Both drugs are strongly antihistaminic and sedating, so combined use can cause pronounced drowsiness, psychomotor impairment and next-day sedation. Diphenhydramine's anticholinergic effects may add confusion and falls risk in older adults.
What this interaction means in plain words
Diphenhydramine and Mirtazapine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Diphenhydramine belongs to Respiratory; Mirtazapine belongs to Central Nervous System.
Why it happens
Additive H1 receptor antagonism and CNS depression.
What to do
Avoid using diphenhydramine as a routine sleep aid with mirtazapine. If needed, use the lowest dose and counsel about driving and alcohol.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Mirtazapine
- Isocarboxazid + Mirtazapine Contraindicated
- Mirtazapine + Phenelzine Contraindicated
- Mirtazapine + Pimozide Contraindicated
- Mirtazapine + Procarbazine Contraindicated
- Mirtazapine + Rasagiline Contraindicated
- Mirtazapine + Selegiline Contraindicated
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Mirtazapine?
MediHelp rates the interaction as moderate. Diphenhydramine and Mirtazapine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Both drugs are strongly antihistaminic and sedating, so combined use can cause pronounced drowsiness, psychomotor impairment and next-day sedation. Diphenhydramine's anticholinergic effects may add confusion and falls risk in older adults.
How serious is the interaction between Diphenhydramine and Mirtazapine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid using diphenhydramine as a routine sleep aid with mirtazapine. If needed, use the lowest dose and counsel about driving and alcohol.
What other medicines interact with Mirtazapine?
MediHelp also lists interactions of Mirtazapine with, for example, Isocarboxazid, Phenelzine, Pimozide. The full list is on the Mirtazapine page.
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