ExoticRx · exoticrx.com/drugs/diphenhydramine
US brand names:Benadryl
Diphenhydramine is dosed at 2–4 mg/kg PO q12h in african grey parrots, per 952. van Zeeland Y. Medication for behavior modification in birds. Vet Clin North Am Exot Anim Pract. 2018;21(1):115-149. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.472 doi:10.1016/j.cvex.2017.08.005 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.10 (Psychotropic and Antiepileptic Agents Used in Birds.a,b). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929. Verify against current literature before clinical use.
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.
Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.
A dog/cat sample is shown here. Cited dosing for all 15 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.
| Species | Route | Dose | Frequency | Evidence | Source |
|---|---|---|---|---|---|
| Dog (Domestic) | PO | 1–2 mg/kg | q8-12h | Moderate | Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.437 (2026-08-01). — Plumb's 10th ed (held) printed p.410, Diphenhydramine monograph spanning p.409-411; page located 2026-08-05 from the book's own running heads, and carries this exact dose under the matching species heading. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 — Plumb's Veterinary Drug Handbook, 10th ed (held), Diphenhydramine monograph, printed p.410 (corpus PDF p.437), DOGS/CATS: "Antihistamine (eg, adjunctive treatment of allergic pruritus or reactions, including angioedema […]" [INDICATION NARROWED 2026-08-12, two readers — the motion-sickness heading on the same page is printed at q8h, and no sedative dose is printed.] CORRECTED 2026-08-13: served 2-4 mg/kg against a printed PO ceiling of 2. Plumb's 10th ed, Diphenhydramine monograph, corpus p.437, DOGS, Antihistamine (extra-label): "a) 1 - 2 mg/kg PO every 8 to 12 hours". The same page prints a separate parenteral regimen, "b) 0.5 - 1 mg/kg IV or IM every 6 to 8 hours", which governs the IM row rather than this one. |
| Cat (Domestic) | PO | 1–2 mg/kg | q8-12h |
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Species references:All African Grey Parrot drugsAll Blue-and-Gold Macaw drugsAll Cat (Domestic) drugsAll Chinchilla drugsAll Degu drugsAll Dog (Domestic) drugsAll Dwarf Hamster drugsAll Ferret drugsAll Gerbil drugsAll Guinea Pig drugsAll Mouse drugsAll Pet Rat drugsAll Rabbit (Domestic) drugsAll Syrian Hamster drugsAll Umbrella Cockatoo drugs
| Moderate |
| Plumb's Veterinary Drug Handbook, 10th ed (2023, held copy; the original seed cited the 9th, which was never consulted) — Plumb's 10th ed (held) printed p.409, Diphenhydramine monograph spanning p.409-411; page located 2026-08-05 from the book's own running heads, verified to name the drug in its body text. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 |