Drug interactions

Doxylamine + Pentobarbital

Severity: Major

Doxylamine and Pentobarbital: major interaction.

Last updated 29 Oct 2026 Sources: US FDA label

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

Pentobarbital is a barbiturate with strong sedative-hypnotic effects, and doxylamine adds further CNS depression. The combination may cause excessive sedation and respiratory depression.

Doxylamine

What this interaction means in plain words

Doxylamine and Pentobarbital can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.

Evidence level: Moderate

Why it happens

Additive CNS depression from barbiturate GABA-A potentiation and central H1 blockade.

What to do

Avoid the combination or use reduced doses. Monitor sedation and respiration closely.

What to ask your pharmacist

Does the benefit of taking both outweigh the risk in my case?
Do I need any blood test, ECG or other check while on both?
What early warning signs should I watch for, and what should I do if they appear?

Bring a full list of your medicines, including over-the-counter products, supplements and herbal remedies, to every pharmacy visit.

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References

Pentobarbital Sodium - FDA drug label (DailyMed) - section 7 Drug Interactions (class statement: antihistamines; "The concomitant use of other central nervous system depressants, including other sedatives or hypnotics, antihistamines, tranquilizers, or alcohol, may produce ") — DailyMed (FDA label)

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Frequently asked questions

Can I take Doxylamine with Pentobarbital?

MediHelp rates the interaction as major. Doxylamine and Pentobarbital can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Pentobarbital is a barbiturate with strong sedative-hypnotic effects, and doxylamine adds further CNS depression. The combination may cause excessive sedation and respiratory depression.

How serious is the interaction between Doxylamine and Pentobarbital?

MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination or use reduced doses. Monitor sedation and respiration closely.

What other medicines interact with Doxylamine?

MediHelp also lists interactions of Doxylamine with, for example, Belladonna and opium, Benzhydrocodone / acetaminophen, Brexanolone. The full list is on the Doxylamine page.

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