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Itraconazole for dogs is an antifungal medication that treats a variety of infections. It’s most commonly prescribed to treat ringworm and cryptococcosis, a serious condition that affects the respiratory and nervous systems.

Because itraconazole is typically a long-term treatment, it’s important for pet parents to understand how it works. Keep reading to learn more about the recommended dosages, efficacy, side effects, and drug interactions associated with itraconazole.

Dosage

The dosage strength and frequency will vary depending on several factors, including your dog’s age, weight, and condition. The standard recommended dose is between 2.5 mg and 5 mg per lb. The dosage amount listed here is for informational purposes only. Always consult your vet for guidance and dosage instructions.

Itraconazole for dogs comes in tablet or liquid form. The tablet form is preferable since it’s more potent. If your dog vomits or refuses to take itraconazole, try giving it with a small portion of high-fat food or a treat. The liquid form works better when given before a meal.

Efficacy

Itraconazole is more effective at treating fungal infections compared to other drugs of its class due to its decreased risk of side effects.

Itraconazole treats an array of fungal infections, including:

Active ingredients in itraconazole

Itraconazole weakens and kills fungal cells by interfering with the production of ergosterol, an important building block of fungal cell walls.

Side effects

Side effects associated with itraconazole are rare, but may indicate liver toxicity. Consult your vet immediately if you notice any of the following symptoms:

  • Nausea

  • Vomiting

  • Diarrhea

  • Jaundice

  • Loss of appetite

Considerations

Itraconazole is not FDA-approved for veterinary use. However, veterinarians commonly and safely prescribe it to dogs diagnosed with fungal infections. If you have any concerns regarding the safety of itraconazole for dogs, talk to your vet.

Pregnant and lactating dogs, as well as dogs with liver disease, should not take itraconazole. Veterinarians may prescribe itraconazole to pregnant or lactating dogs only if the benefits outweigh the risks. Because prolonged use of itraconazole can affect liver function, your veterinarian will conduct regular blood tests to evaluate your dog’s liver enzymes.

High doses of itraconazole can lead to necroulcerative dermatitis, an inflammatory condition that causes skin ulcers.

Drug interactions

The list of drugs that may interact with itraconazole is a long one. Always let your vet know if your dog is taking any medications, including over-the-counter treatments, before starting itraconazole. While most drug interactions are mild, some, particularly cisapride, can cause heart problems.

Itraconazole may interact with the following drugs by affecting the body’s ability to absorb them or increasing the drug’s potency or toxicity:

  • Antacids

  • Corticosteroids

  • Benzodiazepines

  • Sedatives (midazolam)

  • Anticoagulants (warfarin)

  • Tricyclic antidepressants

  • Anti-anxiety drugs (buspirone)

  • Cholesterol medications (statins)

  • Anti-gout medications (colchicine)

  • Antibacterial medications (rifampin)

  • Heartworm medications (ivermectin)

  • Immunosuppressants (cyclosporine)

  • Gastrointestinal motility drugs (cisapride)

  • Anticonvulsants (phenobarbital, phenytoin)

  • Antibiotics (ciprofloxacin, macrolide antiobiotics)

  • Diabetes medications (sulfonylurea antidiabetic agents)

  • Stomach acid secretion suppressants (proton-pump inhibitors)

  • Opioid pain relievers (fentanyl, alfentanil, methadone, meloxicam)

  • Cancer treatments (busulfan, cyclophosphamide, doxorubicin, vincristine)

  • Antihistamines (H2 blockers such as famotidine, cimetidine, and ranitidine)

  • Heart and blood pressure medications (digoxin, disopyramide, calcium channel blockers, quinidine, sildenafil)

Allergic reactions and sensitivity

Little information is available on itraconazole allergies in dogs. If you observe any adverse effects that mimic an allergic reaction, contact your vet immediately.

Frequently asked questions

Do I need a prescription for itraconazole?

Yes, your dog will need a prescription for itraconazole.

How long will my dog need to take itraconazole?

That ultimately depends on the type and severity of the infection, as well as your veterinarian’s advice. However, because most fungi are highly resistant to treatment, some infected dogs may need to take itraconazole for several weeks or months.

What should I do if I miss a dose of itraconazole?

Administering itraconazole exactly according to your veterinarian’s instructions is essential for ensuring the best prognosis. Setting a reminder can help you remember. If you do miss a dose, be sure to give it as soon as possible once you remember. However, if it’s close to time for the next dose, skip the missed dose and resume your normal dosing schedule. Never double up on doses.

My dog seems to be feeling better. Should they stop taking itraconazole?

Antifungals work similarly to antibiotics. You’ll need to give your dog the full course of itraconazole to fully eradicate the infection and prevent it from returning. Failure to do so can result in antifungal resistance. Never stop any treatment regimen unless explicitly instructed to do so by your veterinarian.

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