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Clemastine

First-Generation Antihistamine (H1 Blocker)
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
2 available
Formulations
1

Mechanism of action

Competitive H1-receptor antagonist that blocks histamine-mediated vasodilation, increased vascular permeability, and pruritus. Moderate anticholinergic and sedative properties.

At a glance

Class
First-Generation Antihistamine (H1 Blocker)
Schedule
OTC
Storage
Store at room temperature, protect from moisture

Dosing

🐕

Dog

Used for allergic dermatitis, urticaria, and pruritus
Dose
0.05–0.1 mg/kg
Route
PO
Frequency
q12h
🐈

Cat

Used for feline allergic skin disease
Dose
0.34–0.68 mg/cat
Route
PO
Frequency
q12h
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Other — 1

Strength

Storage

Store at room temperature, protect from moisture

Safety

Monitoring parameters

Pruritus responseSedation level
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Interactions

No documented interactions.

Brands

Other markets

Tavist
Dayhist

FAQs

Frequently asked questions

What is Clemastine?
Clemastine is a first-generation antihistamine (h1 blocker) used in pets. Competitive H1-receptor antagonist that blocks histamine-mediated vasodilation, increased vascular permeability, and pruritus. Moderate anticholinergic and sedative properties.
What is Clemastine used for in pets?
Clemastine is used in veterinary medicine for: Used for allergic dermatitis, urticaria, and pruritus; Used for feline allergic skin disease.
What is the Clemastine dose for dogs?
For dogs, Clemastine is typically dosed as follows — Used for allergic dermatitis, urticaria, and pruritus: 0.05–0.1 mg/kg PO q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
What is the Clemastine dose for cats?
For cats, Clemastine is typically dosed as follows — Used for feline allergic skin disease: 0.34–0.68 mg/cat PO q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
Does Clemastine need a prescription?
Clemastine is available over the counter. Even so, you should consult your veterinarian before giving any medication to your pet.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

References

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

  • Plumb's Veterinary Drug Handbook
  • Withrow & MacEwen's Small Animal Clinical Oncology
  • Merck Veterinary Manual
  • NRC Nutrient Requirements of Dogs and Cats
  • Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

  • ASPCA Animal Poison Control Center Guidelines
  • AAHA Diabetes Management Guidelines
  • ASPCA Poison Control Guidelines
  • RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

  • EPIC Study (J Vet Intern Med 2016)
  • JVIM FAT CAT Study

Regulatory & approvals — 1

  • CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

  • Washington State University VCPL MDR1 Database

Related medicines

Other medicines in the same class (First-Generation Antihistamine).

Chlorpheniramine
Competitively blocks histamine H1 receptors, reducing allergic symptoms including pruritus, urticaria, and oedema; crosses the blood-brain barrier causing sedation
dogcat
Diphenhydramine
Competitively blocks H1 histamine receptors on effector cells, preventing histamine-mediated vasodilation, increased vascular permeability, and pruritus; also has anticholinergic, antitussive, and mild sedative properties
dogcat
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