Drug interactions
Doxylamine + Morphine
Severity: Moderate
Doxylamine and Morphine: 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
Doxylamine is a sedating antihistamine and adds to the central depressant effects of morphine, increasing drowsiness, impaired psychomotor performance and risk of respiratory depression. Older or frail patients are at particular risk.
What this interaction means in plain words
Doxylamine and Morphine 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.
Doxylamine belongs to Respiratory; Morphine belongs to Musculoskeletal.
Why it happens
Additive CNS depression from histamine H1 blockade and opioid receptor agonism.
What to do
Avoid routine use of doxylamine as a sleep aid in patients on opioids, or use the lowest dose and monitor sedation and breathing. Advise against alcohol and driving.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Doxylamine and Morphine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Morphine
- Alvimopan + Morphine Contraindicated
- Isocarboxazid + Morphine Contraindicated
- Morphine + Olanzapine / samidorphan Contraindicated
- Morphine + Phenelzine Contraindicated
- Morphine + Tranylcypromine Contraindicated
- Alfentanil + Morphine Major
Other interactions of Doxylamine
Frequently asked questions
Can I take Doxylamine with Morphine?
MediHelp rates the interaction as moderate. Doxylamine and Morphine 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. Doxylamine is a sedating antihistamine and adds to the central depressant effects of morphine, increasing drowsiness, impaired psychomotor performance and risk of respiratory depression. Older or frail patients are at particular risk.
How serious is the interaction between Doxylamine and Morphine?
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 routine use of doxylamine as a sleep aid in patients on opioids, or use the lowest dose and monitor sedation and breathing. Advise against alcohol and driving.
What other medicines interact with Morphine?
MediHelp also lists interactions of Morphine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Morphine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
