Dog · Canis lupus familiaris · typical adult weight 2.00–80.00 kg
Diphenhydramine is dosed at 2–4 mg/kg IM Single dose or q8h in dogs, per Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.437 (2026-08-01).. Diphenhydramine is used in dogs for Acute allergic reaction, pre-chemotherapy, Allergic reactions, motion sickness, mild sedation. Routes documented in dogs: IM, PO. A typical adult dog weighs 2.00–80.00 kg. ExoticRx lists 2 cited dose rules for Diphenhydramine in dogs, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Benadryl
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| IM | 2–4 mg/kg | Single dose or q8h | Acute | Acute allergic reaction, pre-chemotherapy | Moderate | Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.437 (2026-08-01). |
| PO | 2–4 mg/kg | q8-12h | As needed | Allergic reactions, motion sickness, mild sedation | Moderate | Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.437 (2026-08-01). |
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These ranges are per kg. Enter your dog's weight to get the precise dose and draw-up volume — unit and concentration math done for you.
Competitive antagonist at histamine H1 receptors. Also has anticholinergic, anti-motion sickness, and mild sedative properties.
Sedation common (first-generation). Anticholinergic effects (dry mouth, urinary retention). Ensure product does not contain xylitol or pseudoephedrine. Dogs and cats. Less effective than second-gen antihistamines for pruritus.
Species-specific contraindications and adverse-reaction reports for dogs may differ from canine / feline reference data — consult the primary citations listed with each rule.
Diphenhydramine dose ranges in dogs, with cited source references: IM 2–4 mg/kg Single dose or q8h; PO 2–4 mg/kg q8-12h. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for Diphenhydramine in dogs: IM, PO.
Cited course lengths for Diphenhydramine in dogs include: Acute; As needed. Duration depends on the indication — match it to the specific dose rule in the table above.
Diphenhydramine is indicated in dogs for: Acute allergic reaction, pre-chemotherapy, Allergic reactions, motion sickness, mild sedation.
These are general warnings for Diphenhydramine across species; consult the dog dosing table above for species-specific guidance. Sedation common (first-generation). Anticholinergic effects (dry mouth, urinary retention). Ensure product does not contain xylitol or pseudoephedrine. Dogs and cats. Less effective than second-gen antihistamines for pruritus.
Why a species-specific page? Diphenhydramine pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in dogs — the rules above are the citations specific to this species, not generic recommendations.
Sourced from published veterinary references; awaiting credentialed clinical reviewer. See our editorial process. Reference only — not veterinary advice.