Drug interactions
Promethazine + Scullcap
Severity: Moderate
Promethazine and Scullcap: 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
Scullcap is used traditionally as a sedative herb and may add to the sedation caused by promethazine. This could impair alertness and psychomotor performance.
What this interaction means in plain words
Promethazine and Scullcap 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 depressant effects; scullcap is thought to have GABAergic activity, though the evidence is limited.
What to do
Advise patients to avoid driving or hazardous tasks until the combined response is known. Discourage concurrent use of sedative herbal products with promethazine.
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 Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Promethazine with Scullcap?
MediHelp rates the interaction as moderate. Promethazine and Scullcap 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. Scullcap is used traditionally as a sedative herb and may add to the sedation caused by promethazine. This could impair alertness and psychomotor performance.
How serious is the interaction between Promethazine and Scullcap?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise patients to avoid driving or hazardous tasks until the combined response is known. Discourage concurrent use of sedative herbal products with promethazine.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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