Drug interactions
Dimenhydrinate + Diphenoxylate
Severity: Moderate
Dimenhydrinate and Diphenoxylate: 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
Diphenoxylate, an opioid antidiarrheal, can cause drowsiness, and it is formulated with atropine, which adds anticholinergic effects. Combining it with dimenhydrinate increases sedation and anticholinergic burden, including constipation, urinary retention and possible ileus.
What this interaction means in plain words
Dimenhydrinate and Diphenoxylate 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.
Dimenhydrinate belongs to Respiratory; Diphenoxylate belongs to Gastrointestinal Tract.
Why it happens
Additive CNS depression and additive anticholinergic effects.
What to do
Monitor for oversedation, urinary retention and reduced bowel motility. Avoid use in young children and use extra care in older adults.
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 Dimenhydrinate
Other interactions of Diphenoxylate
Frequently asked questions
Can I take Dimenhydrinate with Diphenoxylate?
MediHelp rates the interaction as moderate. Dimenhydrinate and Diphenoxylate 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. Diphenoxylate, an opioid antidiarrheal, can cause drowsiness, and it is formulated with atropine, which adds anticholinergic effects. Combining it with dimenhydrinate increases sedation and anticholinergic burden, including constipation, urinary retention and possible ileus.
How serious is the interaction between Dimenhydrinate and Diphenoxylate?
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 oversedation, urinary retention and reduced bowel motility. Avoid use in young children and use extra care in older adults.
What other medicines interact with Dimenhydrinate?
MediHelp also lists interactions of Dimenhydrinate with, for example, Belladonna and opium, Brexanolone, Calcium / magnesium / potassium / sodium oxybates. The full list is on the Dimenhydrinate page.
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