Drug interactions
Chlorpheniramine + Doxylamine
Severity: Moderate
Chlorpheniramine and Doxylamine: 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
Two sedating first-generation antihistamines taken together produce duplicated therapy with greater drowsiness, impaired alertness and anticholinergic adverse effects. Doxylamine is often present in OTC sleep and cold products, so inadvertent duplication is common.
What this interaction means in plain words
Chlorpheniramine and Doxylamine 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.
Chlorpheniramine belongs to Respiratory; Doxylamine belongs to Respiratory.
Why it happens
Additive central H1-receptor blockade and anticholinergic activity.
What to do
Avoid using both; check combination cold and sleep products for duplicate antihistamines. Use one agent at the lowest effective dose.
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 Chlorpheniramine
Other interactions of Doxylamine
Frequently asked questions
Can I take Chlorpheniramine with Doxylamine?
MediHelp rates the interaction as moderate. Chlorpheniramine and Doxylamine 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. Two sedating first-generation antihistamines taken together produce duplicated therapy with greater drowsiness, impaired alertness and anticholinergic adverse effects. Doxylamine is often present in OTC sleep and cold products, so inadvertent duplication is common.
How serious is the interaction between Chlorpheniramine and Doxylamine?
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 both; check combination cold and sleep products for duplicate antihistamines. Use one agent at the lowest effective dose.
What other medicines interact with Chlorpheniramine?
MediHelp also lists interactions of Chlorpheniramine with, for example, Belladonna and opium, Benzhydrocodone / acetaminophen, Brexanolone. The full list is on the Chlorpheniramine page.
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