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Voriconazole

Prescription

Second-Generation Triazole Antifungal

Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

2 available

Interactions

3 documented

Formulations

Mechanism of action

Inhibits fungal cytochrome P450-dependent 14α-sterol demethylase, blocking ergosterol synthesis. Extended spectrum over fluconazole including Aspergillus, Fusarium, and many Candida species.

At a glance

Class

Second-Generation Triazole Antifungal

Schedule

Prescription

Storage

Tablets at room temperature; oral suspension refrigerated, use within 14 days; reconstituted IV solution refrigerated

Dosing

🐕

Dog

Used for aspergillosis, fusariosis, and refractory systemic mycoses

Dose

4 mg/kg

Route

PO, IV

Frequency

q12h

🐈

Cat

CAUTION: Cats have significantly reduced voriconazole clearance

Dose

12.5 mg/kg

Route

Frequency

q12h

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. Find a vet near you →

Formulations

💊

Other — 3

Strength

—

Strength

—

Strength

—

Storage

Tablets at room temperature; oral suspension refrigerated, use within 14 days; reconstituted IV solution refrigerated

Safety

Monitoring parameters

Hepatic enzymesSerum voriconazole levels (TDM recommended)Neurological signs in cats

Educational reference only

Interactions

Contraindicated — 2

Phenobarbital

contraindicated

Phenobarbital potently induces CYP2C19 and CYP3A4, reducing voriconazole levels by 50-80%, rendering antifungal therapy ineffective. Voriconazole also inhibits phenobarbital metabolism.

Management: Avoid combination. If both needed, use alternative antifungal (caspofungin, amphotericin B) or alternative anticonvulsant (levetiracetam — no CYP induction).

Cisapride

contraindicated

CYP3A4 inhibition causes cisapride accumulation and fatal cardiac arrhythmias.

Management: NEVER combine. Use metoclopramide as alternative prokinetic.

Major — 1

Cyclosporine (Systemic)

major

Voriconazole potently inhibits CYP3A4, increasing cyclosporine levels 2-3 fold.

Management: Reduce cyclosporine dose by 50%. Monitor trough levels closely.

Educational reference only

Brands

Other markets

Vfend

Vorico

FAQs

Frequently asked questions

›What is Voriconazole?

Voriconazole is a second-generation triazole antifungal used in pets. Inhibits fungal cytochrome P450-dependent 14α-sterol demethylase, blocking ergosterol synthesis. Extended spectrum over fluconazole including Aspergillus, Fusarium, and many Candida species.

›What is Voriconazole used for in pets?

Voriconazole is used in veterinary medicine for: Used for aspergillosis, fusariosis, and refractory systemic mycoses; CAUTION: Cats have significantly reduced voriconazole clearance.

›What is the Voriconazole dose for dogs?

For dogs, Voriconazole is typically dosed as follows — Used for aspergillosis, fusariosis, and refractory systemic mycoses: 4 mg/kg PO/IV q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What is the Voriconazole dose for cats?

For cats, Voriconazole is typically dosed as follows — CAUTION: Cats have significantly reduced voriconazole clearance: 12.5 mg/kg PO q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›Does Voriconazole need a prescription?

Yes. Voriconazole is a prescription medication and should only be administered under veterinary supervision.

Educational reference only

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

Plumb's Veterinary Drug Handbook
Withrow & MacEwen's Small Animal Clinical Oncology
Merck Veterinary Manual
NRC Nutrient Requirements of Dogs and Cats
Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

ASPCA Animal Poison Control Center Guidelines
AAHA Diabetes Management Guidelines
ASPCA Poison Control Guidelines
RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

EPIC Study (J Vet Intern Med 2016)
JVIM FAT CAT Study

Regulatory & approvals — 1

CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

Washington State University VCPL MDR1 Database