medication

Diphenhydramine

Also known as: Benadryl

Chemical structure of Diphenhydramine (PubChem CID 3100)
Structure via PubChem
Half-life
8 h
Typical timing
bedtime
Food rule
either
Default unit
mg

Overview

Diphenhydramine is an antihistamine commonly used to relieve symptoms of allergies, such as sneezing, runny nose, watery eyes, and itching. It is also used to treat insomnia, motion sickness, and some symptoms of Parkinson's disease (such as tremors) or drug-induced extrapyramidal symptoms. As an over-the-counter (OTC) medication, it is widely available under various brand names, most notably Benadryl, and in many combination cold and flu preparations. It is a first-generation antihistamine, meaning it readily crosses the blood-brain barrier, contributing to its sedative effects.

Deep dive

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Known interactions

  • Category rule: supplement × medication
    Note

    Some supplements change how the body processes medications (absorption, liver enzymes, or additive effects).

    Specific pairs are checked against a licensed drug database and shown with their own severity. Always confirm with your provider or pharmacist.

  • Category rule: vitamin × medication
    Note

    Certain vitamins interact with specific medications (e.g., vitamin K with blood thinners).

    Specific pairs are checked against a licensed source; confirm with your provider.

  • Compound-pair rule
    Note

    Additive sedation possible.

    Start at low melatonin dose (0.3–1 mg) when combined with prescription sedatives.

Frequently asked

Sources referenced

["NIH Office of Dietary Supplements (ODS)", "MedlinePlus", "PubChem", "Mayo Clinic", "FDA (Food and Drug Administration) label information", "DrugBank"]

Stackwise compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician.

Related compounds

Others in the medication category or studied for the same goals.

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