Drug interactions
Diphenhydramine + Thiothixene
Severity: Moderate
Diphenhydramine and Thiothixene: 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
Thiothixene is an antipsychotic with sedative and some anticholinergic effects, so combined use with diphenhydramine increases drowsiness and antimuscarinic effects such as dry mouth, constipation, urinary retention and confusion. Diphenhydramine is sometimes used deliberately to treat antipsychotic extrapyramidal symptoms.
What this interaction means in plain words
Diphenhydramine and Thiothixene 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.
Why it happens
Additive CNS depression and muscarinic blockade.
What to do
Monitor for excessive sedation, anticholinergic toxicity and cognitive effects, especially in older patients. Use the lowest effective diphenhydramine dose and reassess the need regularly.
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 Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Thiothixene?
MediHelp rates the interaction as moderate. Diphenhydramine and Thiothixene 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. Thiothixene is an antipsychotic with sedative and some anticholinergic effects, so combined use with diphenhydramine increases drowsiness and antimuscarinic effects such as dry mouth, constipation, urinary retention and confusion. Diphenhydramine is sometimes used deliberately to treat antipsychotic extrapyramidal symptoms.
How serious is the interaction between Diphenhydramine and Thiothixene?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for excessive sedation, anticholinergic toxicity and cognitive effects, especially in older patients. Use the lowest effective diphenhydramine dose and reassess the need regularly.
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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