Competitively blocks histamine H1 receptors, reducing allergic symptoms including pruritus, urticaria, and oedema; crosses the blood-brain barrier causing sedation
At a glance
Class
First-generation antihistamine (H1 receptor antagonist)
Storage
Store below 25°C, protect from light
Dosing
Allergic pruritus / urticaria
Max dose
16 mg/dose; 48 mg/day
Duration: As needed; may use long-term
Acute allergic reaction (adjunct to adrenaline)
Duration: Acute; follow with oral dosing BID for 3-5 days
Allergic pruritus / eosinophilic dermatitis
Max dose
4 mg/dose; 8 mg/day
Duration: As needed
Safety
Urinary retention / prostatic hypertrophy
Anticholinergic effects worsen urinary retention
Glaucoma
Anticholinergic effects may increase intraocular pressure
Concurrent CNS depressants
Additive sedation
Adverse effects
Common
Sedation/drowsiness
Dry mouth
Urinary retention
Serious
CNS excitation (paradoxical, especially cats)
Seizures (overdose)
Pruritus scoreSedation levelUrination
Interactions
No documented interactions.
FAQs
Frequently asked questions
›What is Chlorpheniramine?
Chlorpheniramine is a first-generation antihistamine (h1 receptor antagonist) used in pets. Competitively blocks histamine H1 receptors, reducing allergic symptoms including pruritus, urticaria, and oedema; crosses the blood-brain barrier causing sedation
›What is Chlorpheniramine used for in pets?
Chlorpheniramine is used in veterinary medicine for: Allergic pruritus / urticaria; Acute allergic reaction (adjunct to adrenaline); Allergic pruritus / eosinophilic dermatitis.
›What is the Chlorpheniramine dose for dogs?
For dogs, Chlorpheniramine is typically dosed as follows — Allergic pruritus / urticaria: 0.2–0.5 mg/kg PO BID-TID; Acute allergic reaction (adjunct to adrenaline): 0.2–0.5 mg/kg IM/SC Single dose. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Chlorpheniramine dose for cats?
For cats, Chlorpheniramine is typically dosed as follows — Allergic pruritus / eosinophilic dermatitis: 1–2 mg/cat PO BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Chlorpheniramine?
Common: Sedation/drowsiness, Dry mouth, Urinary retention. Serious (call your vet immediately): CNS excitation (paradoxical, especially cats), Seizures (overdose).
›Does Chlorpheniramine need a prescription?
Chlorpheniramine is available over the counter. Even so, you should consult your veterinarian before giving any medication to your pet.
References
References
Textbooks & handbooks
- Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
- Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
- Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
- National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
- The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/
Clinical guidelines & consensus
- Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
- American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.
Journals & peer-reviewed studies
- Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
- Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
- ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control
Regulatory & approvals
- Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/
Databases
- Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
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.
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