Diphenhydramine: study card

Diphenhydramine — Antihistamine. Study the mechanism, listed uses and warnings from the US label on one sourced card.

Generic name: Diphenhydramine
Class: Antihistamine
Mechanism: Antihistamine with anticholinergic and sedative effects; antihistamines appear to compete with histamine for receptor sites on effector cells.
Used for: Selected immediate allergic reactions when oral therapy is impractical; for anaphylaxis, only adjunctive to epinephrine and standard measures after acute symptoms are controlled; Active treatment of motion sickness when oral diphenhydramine is impractical; Selected parkinsonism settings when oral therapy is impossible or contraindicated
Common side effects: Sedation; Sleepiness; Dizziness; Disturbed coordination; Thickened bronchial secretions
Warnings: Not for neonates or premature infants; Contraindicated in nursing mothers; Not for use as a local anesthetic

Brand questions use only name pairings verified against the linked product source. Unverified pairings are withheld from these questions; the other study content remains available.

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Label date: 20260819 · For learning, not clinical decisions. US label and brand information; always consult the current source.

Source snapshot checked: 2026-10-21. The source document and selected fields were compared. The complete card has not had an independent clinical review.

Practice

Pronunciation

Diphenhydramine: dye-fen-HYE-dra-meen

Pronunciation is shown for the US English generic name.

Body system

Allergy · 10 Drug cards

Compare with related cards

Promethazine

Same body system: Allergy

Mechanism: Phenothiazine H1 receptor blocker with sedative and antiemetic effects and weak dopamine antagonism.

On both cards: Common side effects — Sedation; Dizziness

Only on the Promethazine card: Used for — Allergic rhinitis and conjunctivitis; Urticaria / angioedema (mild); Nausea / vomiting with anesthesia, surgery; Pre-/postoperative sedation · Common side effects — Drowsiness; Blurred vision; Dry mouth · Warnings — Contraindicated in comatose states; Not for lower respiratory symptoms incl. asthma; Neuroleptic malignant syndrome

An item counts as shared only when both cards use the same wording. If a card does not list an item, that is not a statement that the effect never occurs.