Mebendazole: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Mebex, Wormin, Vermox

Species with doses

Dogs, Horses, Sheep and Poultry

General dose range

10–20 mg/kg PO single dose (repeat per cycle) — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• GI nematodes in horses (strongyles, ascarids, pinworms), ruminants and poultry
• Some cestode (tapeworm) infections
• Broad-spectrum benzimidazole deworming (large animals/poultry)

Mebendazole 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

• GI nematodes / Taenia: Papich 5e: 22 mg/kg mixed with food q24h for 3 days, repeated in 3 weeks if needed. Rare idiosyncratic hepatotoxicity reported.

Cattle

• No reference dose for this species: Papich 5e gives mebendazole doses only for dogs and horses and Plumb’s has no monograph.

Horses

• GI nematodes: Papich 5e: 8.8 mg/kg PO. Not in Plumb’s. Check faecal egg-count reduction — benzimidazole resistance is common in cyathostomins.

Goats

• No reference dose for this species: Papich 5e gives mebendazole doses only for dogs and horses and Plumb’s has no monograph.

Sheep

• GI nematodes: Label-sourced — Papich 5e gives only dog and horse doses and Plumb’s has no monograph. Follow the local product label for dose and withdrawal.

Poultry

• GI nematodes / some cestodes: Label-sourced (no Papich 5e poultry dose, no Plumb’s monograph). Follow the local label for dose, meat withdrawal and egg restrictions.

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• No reference dose for this species: Papich 5e gives mebendazole doses only for dogs and horses and Plumb’s has no monograph.

Contraindications

Dogs (idiosyncratic hepatotoxicity — use fenbendazole instead). Early pregnancy at high/repeated doses (benzimidazole teratogenicity concern at high doses). Known hypersensitivity. Confirm benzimidazole susceptibility where resistance is suspected. Observe food-animal withdrawal.

Species-specific warnings

Dogs: Associated with idiosyncratic, sometimes fatal hepatotoxicity in dogs — do NOT use for canine deworming; fenbendazole is the safe benzimidazole choice.

Adverse effects

• Mild transient GI effects (uncommon) in large animals/poultry
• Idiosyncratic HEPATOTOXICITY in dogs (why it is avoided there)
• Reduced efficacy where benzimidazole resistance exists

Drug interactions

• No major systemic therapeutic interactions
• Cross-resistance with other benzimidazoles (fenbendazole, oxfendazole, albendazole)

Pregnancy and lactation

Benzimidazoles are generally regarded as safe in pregnancy at label doses; avoid very high/repeated dosing in early gestation.

Monitoring

• Faecal egg count reduction (efficacy/resistance)
• Withdrawal compliance; class rotation
• (If ever used in dogs — not recommended — liver values)

Toxicity and overdose

Wide safety margin in target large-animal/poultry species (overdose usually only mild GI upset). The notable exception is DOGS, where idiosyncratic hepatotoxicity (sometimes fatal) has occurred — hence fenbendazole is preferred for canine deworming.

Management: Supportive — fluids if needed. For suspected canine hepatotoxicity, discontinue and provide hepatoprotection/monitoring. No specific antidote (wide margin in target species).

Clinical pearls

• A broad benzimidazole for horses, ruminants and poultry — but AVOID in dogs (idiosyncratic, sometimes fatal hepatotoxicity); use fenbendazole for canine deworming
• Benzimidazole resistance is widespread in equine/small-ruminant strongyles — do FECRTs and rotate classes
• Wide safety margin in target species, but still dose to body weight and observe withdrawals

Mechanism of action

Binds parasite β-tubulin and inhibits microtubule polymerisation, disrupting the worm's cytoskeleton, glucose uptake and energy metabolism — killing GI nematodes (and damaging some cestodes). Mammalian tubulin has much lower affinity, giving the wide safety margin; the canine hepatotoxicity is an idiosyncratic (non-mechanism-based) reaction.

Formulations and products

• Oral paste / suspension / granules
• 100 mg tablet (human)
• Mebendazole equine paste (Various) — Mebendazole paste/suspension, Paste / suspension
• Mebex / Vermox — 100 mg tablet; suspension, Tablet / suspension (human-label)

Storage

Paste/suspension/tablets: 15–30 °C, protect from light; shake suspension.

Before you use this dose

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 antiparasitics

• Levamisole
• Levamisole + Oxyclozanide
• Lotilaner
• Lufenuron
• Meglumine Antimoniate
• Melarsomine
• Milbemycin oxime
• Monensin

Frequently asked questions