# Chlorpheniramine Maleate: veterinary dose and monograph > Chlorpheniramine Maleate is a veterinary drug. First-generation H1 antihistamine. Indications include allergic dermatitis / urticaria; anaphylactic shock (adjunct after adrenaline); rhinitis, photo-dermatitis, tail eczema (horses). This monograph lists 5 reference doses for dogs, cats, cattle, horses and ferrets, each with route, frequency and source, plus meat and milk withdrawal periods for food animals. Source: https://vetmasterji.com/drugs/chlorpheniramine · Last reviewed: 2026-10-01 ## At a glance - **Drug class:** Veterinary drug - **Also known as:** Anistamin, Avilin, Avil, Chlor-Trimeton - **Species with doses:** Dogs, Cats, Cattle, Horses and Ferrets - **General dose range:** 0.2–0.5 mg/kg IM q8–12h — check the species tables for the indication - **Routes:** IM, PO - **Last reviewed:** 1 October 2026 ## Indications - Allergic dermatitis / urticaria - Anaphylactic shock (adjunct after adrenaline) - Rhinitis, photo-dermatitis, tail eczema (horses) - Pruritus, serum sickness, transport-induced oedema - Pulmonary emphysema (horses, adjunct) ## Chlorpheniramine Maleate dose by species Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them. ### Dogs *Chlorpheniramine Maleate doses for dogs* | Indication | Dose | Route | Frequency | Duration | | --- | --- | --- | --- | --- | | Atopy / urticaria | 0.2–0.5 mg/kg | PO | q8–12h | — | - Atopy / urticaria: Papich 5e and Plumb’s p.260: 4–8 mg per dog PO q8–12h, not exceeding 0.5 mg/kg q12h; pruritus trial 0.2–0.8 mg/kg PO 2–3 times daily (Rosychuk; Marsella). Injectable use follows the product label. ### Cats *Chlorpheniramine Maleate doses for cats* | Indication | Dose | Route | Frequency | Duration | | --- | --- | --- | --- | --- | | Atopy / pruritus | 2–4 mg per cat PO q12–24h | PO | q12–24h | — | - Atopy / pruritus: Papich 5e: 2 mg per cat q12h PO. Plumb’s p.260: 2–4 mg per cat q12–24h (Hnilica; Rosychuk); pruritus 2–4 mg twice daily (Messinger) or 0.5–2 mg 2–3 times daily (Marsella); mild sedation 1–4 mg q12–24h (Overall). Bitter — capsule or mask the taste. ### Cattle *Chlorpheniramine Maleate doses for cattle* | Indication | Dose | Route | Frequency | Duration | Withdrawal | | --- | --- | --- | --- | --- | --- | | Allergic reactions / urticaria | 0.2–0.5 mg/kg | IM | q8–12h | — | Withdrawal NOT established — treat as extra-label | - Allergic reactions / urticaria: 5–10 mL of Anistamin 10 mg/mL per adult cow. Dose per Indian product label (Anistamin); Papich 5e states no large-animal dose has been reported and Plumb’s 10e (pp.251–253) gives no cattle dose. Label dose 0.2–0.5 mg/kg IM q8–12h. Follow the product label withdrawal. ### Horses *Chlorpheniramine Maleate doses for horses* | Indication | Dose | Route | Frequency | Duration | | --- | --- | --- | --- | --- | | Histamine-related pruritus (e.g. insect-bite hypersensitivity) | 0.25 mg/kg | PO | q12h | — | - Histamine-related pruritus (e.g. insect-bite hypersensitivity): Plumb’s 10e p.252 (extra-label): adjunctive treatment and prevention of histamine-related pruritic conditions such as insect-bite hypersensitivity — 0.25 mg/kg PO every 12 hours. A pharmacokinetic study found a single 0.5 mg/kg PO dose less efficacious than other antihistamines. No injectable horse dose is given; Papich 5e reports no large-animal dose. ### Goats *Chlorpheniramine Maleate doses for goats* | Indication | Dose | Route | Frequency | Duration | Withdrawal | | --- | --- | --- | --- | --- | --- | | No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — | — | - No reference dose for this species: No goat chlorpheniramine dose appears in Papich 5e (no large-animal dose reported) or Plumb’s 10e (pp.251–253 dose dogs, cats, horses, birds and ferrets only), and the previous row had no source. ### Sheep *Chlorpheniramine Maleate doses for sheep* | Indication | Dose | Route | Frequency | Duration | Withdrawal | | --- | --- | --- | --- | --- | --- | | No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — | — | - No reference dose for this species: No sheep chlorpheniramine dose appears in Papich 5e (no large-animal dose reported) or Plumb’s 10e (pp.251–253 dose dogs, cats, horses, birds and ferrets only), and the previous row had no source. ### Pigs *Chlorpheniramine Maleate doses for pigs* | Indication | Dose | Route | Frequency | Duration | Withdrawal | | --- | --- | --- | --- | --- | --- | | No reference dose for this species | Not established in Papich 5e or Plumb’s 10e — do not extrapolate from another species | — | — | — | — | - No reference dose for this species: No pig chlorpheniramine dose appears in Papich 5e (no large-animal dose reported) or Plumb’s 10e (pp.251–253 dose dogs, cats, horses, birds and ferrets only), and the previous row had no source. ### Buffalo No buffalo-specific doses are on file, so buffalo are dosed as cattle. *Chlorpheniramine Maleate doses for buffalo* | Indication | Dose | Route | Frequency | Duration | Withdrawal | | --- | --- | --- | --- | --- | --- | | Allergic reactions / urticaria | 0.2–0.5 mg/kg | IM | q8–12h | — | Withdrawal NOT established — treat as extra-label | - Allergic reactions / urticaria: 5–10 mL of Anistamin 10 mg/mL per adult cow. Dose per Indian product label (Anistamin); Papich 5e states no large-animal dose has been reported and Plumb’s 10e (pp.251–253) gives no cattle dose. Label dose 0.2–0.5 mg/kg IM q8–12h. Follow the product label withdrawal. ### Ferrets *Chlorpheniramine Maleate doses for ferrets* | Indication | Dose | Route | Frequency | Duration | | --- | --- | --- | --- | --- | | Pruritus / allergic disease | 1–2 mg/kg | PO | q8–12h | — | - Pruritus / allergic disease: Plumb's p.260 (Williams 2000): 1–2 mg/kg PO 2–3 times a day. ## Contraindications Hypersensitivity. Caution with concurrent CNS depressants. Narrow-angle glaucoma. Urinary retention. ## Species-specific warnings > **Caution:** Dogs: 0.2–0.5 mg/kg IM q8–12h or 4–8 mg PO q8–12h. Sedation expected. > **Caution:** Cats: 2 mg per cat PO q12h. Watch for paradoxical excitement. > **Caution:** Horses: Transport oedema / photo-dermatitis: 0.2 mg/kg IM. Tail-rub eczema: 0.2 mg/kg IM q8–12h. > **Caution:** Cattle: Pheniramine combinations (Avilin) widely used in cattle. Withdrawal: 7 d slaughter / 2 d milk. ## Adverse effects - Sedation / drowsiness - Anticholinergic — dry mouth, mydriasis, ileus - Excitement / paradoxical reaction (cats) ## Drug interactions - CNS depressants (opioids, alpha-2 agonists, anaesthetics, alcohol): ADDITIVE sedation - Anticholinergic drugs (atropine, tricyclic antidepressants): additive anticholinergic effects (urinary retention, ileus, mydriasis) - MAO inhibitors (selegiline): potentiate anticholinergic effects - Beta-blockers: blunted bronchodilator response in asthma / anaphylaxis - Epinephrine: COMPLEMENTARY in anaphylaxis (epi first, antihistamine second-line) - Phenytoin / phenobarbital: induce hepatic metabolism — may reduce antihistamine effect ## Pregnancy and lactation Generally considered safe at therapeutic doses. Crosses placenta in low amounts. FDA Category B (human). Used widely in pregnant animals for allergic reactions, transport oedema. ## Monitoring - Sedation depth — usually mild - Cats: paradoxical excitement — switch to alternative if observed - Urinary output (anticholinergic retention) - Withdrawal periods: cattle 7 d slaughter / 2 d milk (pheniramine combinations — Avilin) - Clinical response to allergic reaction — typically within 30–60 min - Adjunct to epinephrine for anaphylaxis, NEVER monotherapy ## Toxicity and overdose Sedation is the most common side effect — usually mild. Anticholinergic: dry mouth, mydriasis, urinary retention, ileus. Cats: PARADOXICAL EXCITEMENT possible at higher doses — switch to alternative antihistamine if observed. Overdose: severe anticholinergic syndrome — mydriasis, tachycardia, hyperthermia, agitation, seizures, coma. Pheniramine combinations: similar profile. Management: No specific antidote. Supportive: IV fluids, diazepam 0.5 mg/kg IV for excitement / seizures, active cooling for hyperthermia, beta-blocker (esmolol) for tachyarrhythmias. Activated charcoal if recent ingestion. Physostigmine 0.02 mg/kg IV slow can reverse central anticholinergic effects but rarely needed and risks cholinergic crisis. ## Clinical pearls - Allergic dermatitis / urticaria: 0.2–0.5 mg/kg IM or 4–8 mg per dog PO q8–12h - Cat atopy / pruritus: 2 mg per cat PO q12h — first-line first-generation antihistamine in cats - Anaphylaxis adjunct: 0.2–0.5 mg/kg IM/IV AFTER epinephrine (0.01 mg/kg IM) + corticosteroid (dexamethasone 0.5 mg/kg IV) - Transport oedema (horses): 0.2 mg/kg IM single dose - Photo-dermatitis (cattle): 0.2 mg/kg IM q8–12h - Cats with paradoxical excitement on chlorpheniramine: switch to cetirizine (1 mg/kg PO q24h) or cyproheptadine (1.1 mg/kg PO q12h) - For chronic atopy: second-generation non-sedating antihistamines (cetirizine, fexofenadine) may be preferred - NEVER alone for anaphylactic shock — epinephrine is first-line, antihistamine is supportive ## Mechanism of action First-generation alkylamine H1 histamine receptor antagonist (with some pheniramine combination formulations sharing the same class). Competitively blocks H1 receptors → reduces histamine-mediated vasodilation, smooth muscle contraction, and pruritus. Crosses blood-brain barrier (vs newer non-sedating antihistamines) — sedation is the predominant side effect. Also has weak anticholinergic and mild sedative properties. Useful adjunct (NOT primary) for type I hypersensitivity / anaphylaxis — epinephrine is the first-line. ## Formulations and products - Anistamin 10 mg/mL (Intas, 50 / 100 mL) - Avilin 22.75 mg/mL pheniramine maleate (MSD, 10 / 33 mL) - Anistamin (Intas (Neovet)) — Chlorpheniramine maleate 10 mg/mL, Injection - Avilin VET (MSD Animal Health) — Pheniramine maleate 22.75 mg/mL, Injection - CPM-Sure (Assure Biotech, Jagadhri (HR)) — 10 mg/mL, Injection ## Storage Tablets: 15–25 °C, dry, protected from light. Injection: 15–25 °C, protect from light. Multidose vial: discard 28 days after broaching. Pheniramine combinations: per product label. ## Before you use this dose > **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision. ## Other hormones, emergency drugs, supplements and other drugs - [Carbimazole](https://vetmasterji.com/drugs/carbimazole) - [Carboplatin](https://vetmasterji.com/drugs/carboplatin) - [Cetirizine](https://vetmasterji.com/drugs/cetirizine) - [Chlorambucil](https://vetmasterji.com/drugs/chlorambucil) - [Clenbuterol](https://vetmasterji.com/drugs/clenbuterol) - [Clomipramine](https://vetmasterji.com/drugs/clomipramine) - [Clopidogrel](https://vetmasterji.com/drugs/clopidogrel) - [Cloprostenol](https://vetmasterji.com/drugs/cloprostenol) ## Frequently asked questions ### What is the dose of Chlorpheniramine Maleate for dogs? Reference doses for Chlorpheniramine Maleate in dogs: 0.2–0.5 mg/kg PO q8–12h (Atopy / urticaria). Confirm against the label and the patient before use. ### What is the dose of Chlorpheniramine Maleate for cats? Reference doses for Chlorpheniramine Maleate in cats: 2–4 mg per cat PO q12–24h PO q12–24h (Atopy / pruritus). Confirm against the label and the patient before use. ### What is the dose of Chlorpheniramine Maleate for cattle? Reference doses for Chlorpheniramine Maleate in cattle: 0.2–0.5 mg/kg IM q8–12h (Allergic reactions / urticaria). Confirm against the label and the patient before use. ### What is the withdrawal period for Chlorpheniramine Maleate? Cattle, IM (Allergic reactions / urticaria): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ. ### When should Chlorpheniramine Maleate not be used? Hypersensitivity. Caution with concurrent CNS depressants. Narrow-angle glaucoma. Urinary retention. ### What are the side effects of Chlorpheniramine Maleate in animals? Sedation / drowsiness; Anticholinergic — dry mouth, mydriasis, ileus; Excitement / paradoxical reaction (cats). ## Sources - Intas Animal Health catalogue · Anistamin - MSD Animal Health catalogue · Avilin VET - Plumb's Veterinary Drug Handbook - Papich, Papich Handbook of Veterinary Drugs, 5th edition --- VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.