Itraconazole Side Effects in Cats

Itraconazole is an antifungal drug effective against most types of fungal infections. It works by inhibiting enzymes that produce an important part of fungal cell walls, causing the cells to rupture and die. While itraconazole has not yet been registered for veterinary use, it is an effective treatment for cats who cannot tolerate standard ringworm treatments. It also works well in cats that do not respond to conventional treatment. However, like all medications, itraconazole may have some side effects.

  1. Lethargy

    • Itraconazole may cause lethargy or drowsiness in cats. In humans, headache, depression and dizziness are also possible side effects. These are hard to detect in pets, however, and may look much like lethargy. On their own, these symptoms are not serious, but if they persist or worsen, they could indicate more serious problems.

    Digestive Problems

    • Cats that receive itraconazole treatment may suffer from digestive problems, including vomiting and diarrhea. Some cats may also show a decrease in appetite. These side effects may be minor or they can become serious. Pet owners should contact their veterinarians if their cats suffer from digestive problems for more than a few days. Persistent problems with digestion may indicate a serious reaction to the drug.

    Drug Interactions

    • Itraconazole, when taken along with other medications such as cisapride (a constipation and acid reflux drug,) digoxin (a heart drug derived from digitalis or foxglove) or antacids may cause a drug interaction. Anticoagulants, antidiabetic medication, H2 blockers and other medications may also create a reaction. The specific effects of a drug interaction vary by drug and by individual. Some possibilities include irregular heartbeat and very low blood sugar.

    Liver Problems

    • An uncommon but serious side effect of itraconazole in cats is hepatitis, or inflammation of the liver. This problem is often self-healing but can cause jaundice, or yellowing of the eyes and skin, and abdominal discomfort. Some cats may appear to gain weight from fluid accumulation in the limbs and abdomen. Liver-related side effects can also create or aggravate digestive problems.