# Loratadine: veterinary dose and monograph

> Loratadine is a veterinary drug. A second-generation, NON-SEDATING H1-antihistamine — used for allergic conditions (allergic dermatitis/pruritus, urticaria, allergic rhinitis) where drowsiness is undesirable. Indications include allergic pruritus / atopic dermatitis (adjunct; individual response); urticaria / allergic skin reactions; allergic rhinitis / mild allergic signs where non-sedating antihistamine is wanted. This monograph lists 3 reference doses for dogs and cats, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/loratadine · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Veterinary drug
- **Also known as:** Claritin, Lorfast, Alaspan
- **Species with doses:** Dogs and Cats
- **General dose range:** 0.25–1.1 mg/kg PO q24h or divided q12h — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- Allergic pruritus / atopic dermatitis (adjunct; individual response)
- Urticaria / allergic skin reactions
- Allergic rhinitis / mild allergic signs where non-sedating antihistamine is wanted

## Loratadine 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

*Loratadine doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Antihistamine | 0.25–1.1 mg/kg | PO | q24h or divided q12h | — |

- Antihistamine: Plumb’s 10e p.777 (extra-label): anecdotal doses range from 0.25–1.1 mg/kg PO once daily or divided twice daily. Practically: small dogs 5 mg/dog once daily; medium dogs 10 mg/dog once daily; large dogs 10 mg/dog twice daily (per dog, NOT per kg). Papich 5e has no loratadine monograph.

### Cats

*Loratadine doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Antihistamine (per kg) | 0.5 mg/kg | PO | q24h | — |
| Antihistamine (per cat) | 2.5–5 mg/cat | PO | q24h | — |

- Antihistamine (per kg): Plumb’s 10e p.778 (extra-label): anecdotal 0.5 mg/kg PO once daily. Papich 5e has no loratadine monograph.
- Antihistamine (per cat): Plumb’s 10e p.778 (extra-label): anecdotal 2.5–5 mg per cat (NOT mg/kg) PO once daily.

## Contraindications

Combination products containing PSEUDOEPHEDRINE/decongestants (toxic to pets — avoid). Known hypersensitivity. Significant hepatic impairment (hepatically metabolised). Use plain loratadine only.

## Species-specific warnings

> **Caution:** Dogs: Avoid "loratadine-D"/decongestant combination products — the pseudoephedrine component is toxic (agitation, tachycardia, hypertension, hyperthermia). Use plain loratadine only.

## Adverse effects

- Non-sedating (minimal drowsiness) — its main advantage
- Occasional GI upset
- Modest/variable antipruritic efficacy
- Anticholinergic effects minimal (2nd-generation)

## Drug interactions

- CYP3A4/2D6 inhibitors (ketoconazole, macrolides): may raise loratadine levels
- CNS depressants: minimal additive effect (non-sedating)
- Avoid pseudoephedrine-containing combination products (pet toxicity)
- May suppress allergy skin-test reactions — withdraw before intradermal testing

## Pregnancy and lactation

Limited veterinary data; considered relatively low-risk but use only if needed.

## Monitoring

- Pruritus response over a 1–2 week trial (individual)
- Confirm the product is PLAIN loratadine (no pseudoephedrine)
- Withdraw before intradermal allergy testing

## Toxicity and overdose

Wide safety margin; overdose is usually limited to mild GI upset (and, at high doses, possible mild CNS/cardiac effects). The important toxicity risk is really from PSEUDOEPHEDRINE in combination "loratadine-D" products — pseudoephedrine causes serious agitation/tachycardia/hypertension in dogs and cats.

Management: Supportive; no specific antidote. For a pseudoephedrine-containing combination ingestion, treat the sympathomimetic toxicosis (decontaminate, sedation with acepromazine/phenothiazine, manage tachycardia/hypertension/hyperthermia). Plain loratadine overdose is generally mild.

## Clinical pearls

- A non-sedating, once-daily antihistamine — useful when first-generation antihistamines' drowsiness is a problem, though antipruritic efficacy in atopy is modest and individual (worth a 1–2 week trial)
- CRUCIAL: dispense PLAIN loratadine — many human "loratadine-D/decongestant" products contain PSEUDOEPHEDRINE, which is toxic to dogs and cats
- Stop antihistamines before intradermal allergy testing (they blunt reactions)
- Not a substitute for steroids/oclacitinib/lokivetmab in significant atopic dermatitis — best as an adjunct or for mild disease

## Mechanism of action

A selective peripheral H1-receptor antagonist that blocks histamine-mediated pruritus, vasodilation and wheal formation. Being a second-generation antihistamine it poorly crosses the blood–brain barrier (little central H1 blockade → minimal sedation) and has negligible anticholinergic activity. Its active metabolite (desloratadine) contributes to a long duration, allowing once-daily dosing.

## Formulations and products

- 10 mg tablet
- Syrup 1 mg/mL (5 mg/5 mL)
- Claritin / Lorfast — 10 mg tablet; 5 mg/5 mL syrup, Tablet / syrup (human-label)

## Storage

Tablets/syrup: 15–30 °C, dry, protect from light.

## 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.

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## Frequently asked questions

### What is the dose of Loratadine for dogs?

Reference doses for Loratadine in dogs: 0.25–1.1 mg/kg PO q24h or divided q12h (Antihistamine). Confirm against the label and the patient before use.

### What is the dose of Loratadine for cats?

Reference doses for Loratadine in cats: 0.5 mg/kg PO q24h (Antihistamine (per kg)); 2.5–5 mg/cat PO q24h (Antihistamine (per cat)). Confirm against the label and the patient before use.

### When should Loratadine not be used?

Combination products containing PSEUDOEPHEDRINE/decongestants (toxic to pets — avoid). Known hypersensitivity. Significant hepatic impairment (hepatically metabolised). Use plain loratadine only.

### What are the side effects of Loratadine in animals?

Non-sedating (minimal drowsiness) — its main advantage; Occasional GI upset; Modest/variable antipruritic efficacy; Anticholinergic effects minimal (2nd-generation).

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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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.