Voriconazole: what it is and why it matters

Voriconazole (brand name Vfend) is a prescription antifungal used for serious fungal infections that can be life‑threatening—think invasive aspergillosis and some Candida infections. It’s stronger than common antifungals like fluconazole for certain bugs, but that power comes with more side effects and drug interactions. If your doctor prescribes it, you’ll want to know how to take it safely and what to watch for.

When doctors use voriconazole

Doctors reach for voriconazole when infections don’t respond to simpler drugs or when the fungus is one that voriconazole treats reliably. Typical cases include invasive aspergillosis, severe infections in people with weakened immune systems, and some rare molds. It’s available as an IV and as oral tablets, so treatment can start in the hospital and continue at home if needed.

Adults often start with a loading dose (commonly 400 mg every 12 hours for two doses) then move to a maintenance dose (often 200 mg every 12 hours). Doses are weight‑based for IV and need change for children or people with liver problems. Don’t change doses on your own—dose adjustments are common and based on clinical response, liver tests, and sometimes drug levels.

What to watch for (side effects & interactions)

Voriconazole can cause visual changes—blurred vision or seeing flashes—usually early in treatment and often reversible. It can also irritate the liver, so doctors check liver enzymes before and during therapy. Common complaints include nausea, headache, and skin sensitivity to sunlight. Long‑term use may raise the risk of skin thickening or even skin cancers, so sun protection is important.

Drug interactions are a big deal. Voriconazole affects and is affected by many drugs because it works on CYP enzymes in the liver. That means it can raise levels of warfarin, certain statins, benzodiazepines, and others—sometimes dangerously. Strong enzyme inducers like rifampin or carbamazepine can make voriconazole ineffective. Even grapefruit and some herbal products can cause trouble. Tell your doctor and pharmacist every medication and supplement you take.

Some people metabolize voriconazole differently because of genetics (CYP2C19 variants). That alters blood levels and the risk of side effects. For this reason, doctors may use therapeutic drug monitoring—measuring trough levels—to keep concentrations in a safe, effective range (commonly targeted around 1–5.5 µg/mL, though targets vary by situation).

Watch for red flags: jaundice, very dark urine, severe abdominal pain, signs of a serious allergic reaction, or sudden severe vision changes. If any of those happen, stop the drug and contact your health provider immediately.

Practical tips: take voriconazole on an empty stomach for better absorption unless your doctor tells you otherwise; avoid alcohol while your liver is being checked; protect your skin from sun exposure; and keep a list of all meds handy to share with your care team. Always follow your provider’s instructions—stopping or changing the dose without advice can make the infection worse or increase risk.

If you have questions about side effects, drug interactions, or dosing, ask your doctor or pharmacist. Voriconazole can save lives when used correctly, but it needs careful monitoring and respect for its risks.