Levamisole + Oxyclozanide: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Nilzan, Tolzan Plus-L

Species with doses

Cattle, Goats, Sheep and Buffalo

General dose range

7.5–15 mg/kg PO once — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Mixed gastrointestinal roundworm + liver fluke infestation
• Adult & immature paramphistome (conical fluke) infection
• Cattle / sheep / goat strategic deworming programme

Levamisole + Oxyclozanide 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.

Cattle

• Roundworms + liver fluke + paramphistomum (Tolzan Plus-L): Label-sourced (Tolzan Plus-L: 90 mL per 300 kg) — the combination has no Papich 5e or Plumb’s monograph. Levamisole component 7.5 mg/kg (Plumb’s/Papich levamisole cattle 7.5–8 mg/kg PO). Merck: oxyclozanide slaughter withdrawal 3–14 days, milk 60 h — follow the product label for the combination.

Goats

• Roundworms + liver fluke: Label-sourced (the combination has no Papich 5e or Plumb’s 10e monograph). Levamisole component 7.5 mg/kg — BELOW Plumb’s 10e p.745 goat dose for levamisole alone (12 mg/kg PO, 1.5× the sheep dose), so roundworm efficacy in goats may be reduced. Plumb’s 10e p.744: IM contraindicated in goats; use is controversial in fibre-producing goats. Follow the product label withdrawal.

Sheep

• Roundworms + liver fluke: Label-sourced (Tolzan Plus-L: 9 mL per 30 kg). Levamisole component 7.5 mg/kg (Plumb’s sheep 7.5–8 mg/kg PO). Follow the product label withdrawal. Sheep are relatively sensitive to levamisole toxicity.

Buffalo

• Roundworms + liver fluke + amphistomes: MSD Nilzan/Tolzan Plus-L labels buffalo with cattle: levamisole 7.5 mg/kg + oxyclozanide dose in the combined suspension (≈1 mL/3.3 kg). Especially useful for amphistomosis (rumen flukes), a major buffalo problem in India.

Contraindications

Hypersensitivity. Severe hepatic / renal disease. Concurrent organophosphate dosing (levamisole has cholinergic action). Pyrantel / morantel concurrent dosing (additive nicotinic toxicity).

Species-specific warnings

Cattle: Standard combined dewormer + flukicide. PO route. 14 d slaughter withdrawal.

Goats: Goats clear levamisole faster than cattle — may need 1.5× dose. Sensitive to overdose.

Sheep: More sensitive to levamisole than cattle — strict dose accuracy. PO only (SC has caused fatalities).

Horses: NOT used in horses — ivermectin / moxidectin / triclabendazole alternatives are preferred.

Dogs: NOT used in dogs — narrow margin.

Cats: NOT used in cats.

Adverse effects

• Salivation, lacrimation, transient tremors (levamisole-related, dose-dependent)
• Mild GI upset
• Local injection-site reaction (when given parenterally)

Drug interactions

• Other nicotinic agonists (pyrantel, morantel): additive — DO NOT combine
• Other cholinesterase inhibitors (organophosphates): synergistic cholinergic toxicity — avoid within 30 days of OP dipping
• Other salicylanilides (closantel, rafoxanide): same flukicide mechanism — do NOT combine
• Atropine: ANTAGONISES levamisole cholinergic effects — useful for accidental small-animal exposure
• Bromsalan flukicides: combination has caused cattle fatalities — AVOID

Pregnancy and lactation

Generally safe in pregnant ruminants at therapeutic doses. Crosses placenta in low amounts. Used widely in pregnant breeding stock.

Monitoring

• Exact body weight before dosing — narrow margin in sheep
• Withdrawal periods: 14 d slaughter (cattle/sheep); 28 h milk (verify per jurisdiction)
• Faecal egg count reduction test at 14 days post-treatment — resistance is widespread in sheep / goats
• Cholinergic signs (SLUD, tremors) at 1 h post-dose — atropine if marked
• Liver enzymes on repeated dosing (oxyclozanide component)

Toxicity and overdose

Levamisole component: cholinergic toxicity at high doses — SLUD (salivation, lacrimation, urination, defaecation), muscle tremors, ataxia. Sheep especially sensitive. Cattle / goats: occasional sudden collapse at high SC doses (avoided by giving PO). Oxyclozanide component: hepatotoxicity at very high doses; transient softening of faeces. Combination is generally well tolerated at label dose.

Management: ATROPINE 0.04 mg/kg IM/IV — titrate to drying of secretions for levamisole cholinergic toxicity. Supportive: IV fluids, anti-emetic. Hepatic protection (SAMe) if oxyclozanide overdose. Most overdoses resolve within 12–24 h with prompt atropine.

Clinical pearls

• Cattle / sheep / goats: 90 mL Tolzan Plus-L per 300 kg PO (cattle) or 9 mL per 30 kg PO (sheep/goat) single dose
• Combined GI nematodes + adult fluke + rumen fluke (Paramphistomum) coverage — one-dose convenience
• Sheep are MORE SENSITIVE to levamisole than cattle — avoid SC route, use PO at label dose
• NEVER combine with pyrantel / morantel — additive cholinergic
• NEVER within 30 days of OP dipping — synergistic cholinergic
• FECRT at 14 days — levamisole resistance is widespread in southern hemisphere sheep
• Adult fluke only — oxyclozanide doesn't kill immature stages; use triclabendazole or closantel for early disease
• Faeces softening for 1–2 days is normal and expected

Mechanism of action

COMBINATION dewormer. LEVAMISOLE (imidazothiazole): cholinergic agonist on nematode nicotinic ACh receptors → spastic paralysis → expulsion. Effective against GI roundworms (Haemonchus, Trichostrongylus, Ostertagia), lungworms. Also has immunomodulatory effects (T-cell stimulation). OXYCLOZANIDE (salicylanilide): uncouples mitochondrial oxidative phosphorylation in adult Fasciola hepatica and Paramphistomum (rumen flukes) — adult-only activity. Combined product covers nematodes + flukes + rumen flukes in one dose.

Formulations and products

• Nilzan suspension — Levamisole 1.5 % + Oxyclozanide 3 % (MSD)
• Tolzan Plus-L — Levamisole 2.5 % + Oxyclozanide 3.4 % (MSD, 120 mL / 1 L)
• Tolzan Plus-L (MSD Animal Health) — Oxyclozanide 3.4 % + Levamisole 2.5 %, Oral suspension
• Tolzan F VET (MSD Animal Health) — Oxyclozanide 3.4 %, Oral suspension (flukicide only)
• Raffolev Plus (Mankind Veticura) — Rafoxanide 3 % + Levamisole 3 %, Oral suspension (combination)
• Oxy-D-Worm (Assure Biotech, Jagadhri (HR)) — Oxyclozanide 60 mg + Levamisole HCl 30 mg + Silymarin 4 mg per mL, Oral suspension
• Oxy-D-Sure Bolus (Assure Biotech, Jagadhri (HR)) — Oxyclozanide 4000 mg + Levamisole HCl 2000 mg + Silymarin 300 mg, Uncoated oral bolus
• Zonax DS (Micro Animal Health Care (Micro Labs group), Bengaluru) — Oxyclozanide 6 % w/v + Levamisole 3 % w/v, Oral suspension

Storage

Oral suspension: 15–25 °C, shake well before use, protected from light. Multidose bottles: discard 28 days after broaching. Do NOT freeze.

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

• Imidacloprid
• Imidocarb Dipropionate
• Ivermectin
• Levamisole
• Lotilaner
• Lufenuron
• Mebendazole
• Meglumine Antimoniate

Frequently asked questions