Antifungal. Voriconazole is an antifungal agent used to treat serious fungal infections, such as invasive aspergillosis or candidemia. By "effects, " I will assume you refer to adverse effects. The most common significant adverse effects include hallucinations, visual impairment, and impairment of renal function. Others include rash, fever, chills, headache, n/v, and hypokalemia.