What You Should Know About Itraconazole Side Effects

If your doctor has prescribed Itraconazole, you're probably wondering what side effects to expect. Like all medications, Itraconazole can cause side effects — but knowing what's normal and what's a warning sign can help you feel more confident about your treatment.

Itraconazole is a triazole antifungal used to treat serious fungal infections including blastomycosis, histoplasmosis, aspergillosis, and onychomycosis (nail fungus). For a complete overview of the medication, see our guide on what Itraconazole is and how it works.

This article covers the most common side effects, the serious ones you need to watch for, and clear guidance on when to contact your doctor.

Common Side Effects of Itraconazole

Most people who take Itraconazole tolerate it well, but some side effects are fairly common. These are usually mild and may improve as your body adjusts to the medication:

• Nausea (affects about 11% of patients) — This is the most frequently reported side effect. Taking Itraconazole capsules with food can help reduce nausea.
• Diarrhea (affects about 10% of patients) — Usually mild and temporary. Stay hydrated and contact your doctor if it becomes severe.
• Abdominal pain or stomach discomfort — Mild stomach upset is common, especially in the first few days of treatment.
• Headache — Usually mild and manageable with over-the-counter pain relievers (check with your doctor first about drug interactions).
• Vomiting — Less common than nausea but can occur, especially at higher doses.
• Rash — Mild skin rashes can happen. However, a severe or spreading rash needs immediate medical attention (see serious side effects below).
• Dizziness — Some people feel lightheaded, especially when standing up quickly.
• Fatigue — Feeling more tired than usual is a common complaint during treatment.
• Elevated liver enzymes — Your doctor may catch this on blood tests. Mild elevations often don't cause symptoms but need monitoring.

Serious Side Effects: When to Call Your Doctor Immediately

While serious side effects are less common, Itraconazole does carry some important warnings. Call your doctor right away — or go to the emergency room — if you experience any of the following:

Heart Problems (Boxed Warning)

Itraconazole carries an FDA boxed warning — the most serious type of warning — about congestive heart failure (CHF). The drug has negative inotropic effects, meaning it can weaken the heart's ability to pump blood. Watch for:

• Shortness of breath, especially when lying down or with activity
• Swelling in your feet, ankles, or legs
• Rapid weight gain (several pounds in a few days)
• Unusual tiredness or weakness
• Rapid or irregular heartbeat

Important: Itraconazole should not be used for nail fungus in patients who have or have had congestive heart failure. If you have any heart conditions, make sure your doctor knows before starting this medication.

Liver Problems

Itraconazole can cause serious liver damage, including rare cases of liver failure that have been fatal. Contact your doctor immediately if you notice:

• Yellowing of your skin or the whites of your eyes (jaundice)
• Dark-colored urine
• Pale or clay-colored stools
• Severe nausea or vomiting that doesn't stop
• Unusual fatigue or weakness
• Loss of appetite that lasts more than a few days
• Pain in the upper right side of your abdomen

Your doctor should check your liver function with blood tests before starting Itraconazole and periodically during treatment, especially if you're on the medication for more than a month.

Severe Skin Reactions

Rarely, Itraconazole can cause Stevens-Johnson syndrome, a serious skin condition. Seek emergency care if you develop:

• Widespread skin rash with blistering or peeling
• Sores in your mouth, throat, or eyes
• Fever with a skin rash

Nerve Problems

Peripheral neuropathy (nerve damage) can occur. Tell your doctor if you experience:

• Tingling or numbness in your hands or feet
• Burning sensations in your extremities
• Weakness in your arms or legs

Hearing Changes

Some patients report hearing loss while taking Itraconazole. This is usually temporary and reversible after stopping the medication, but you should report any hearing changes to your doctor right away.

Allergic Reactions

Although rare, anaphylaxis (a severe allergic reaction) can occur. Call 911 if you experience:

• Difficulty breathing or swallowing
• Swelling of your face, lips, tongue, or throat
• Severe dizziness or fainting
• Hives or severe itching

Side Effects by Treatment Length

The side effects you experience may vary depending on how long you take Itraconazole:

Short-term treatment (1-2 weeks): For conditions like oropharyngeal candidiasis, side effects are usually minimal. Nausea and stomach upset are the most likely complaints.

Pulse therapy for nail fungus (1 week on, 3 weeks off): The on-off schedule gives your body breaks, which many patients find easier to tolerate. Side effects tend to occur mainly during the "on" weeks.

Long-term treatment (months): For systemic fungal infections requiring months of treatment, side effects like fatigue and liver enzyme changes become more of a concern. Regular blood monitoring is essential.

How to Manage Common Side Effects

Here are practical tips for dealing with the most common Itraconazole side effects:

• For nausea: Take capsules with a full meal. Avoid spicy or greasy foods around dosing time. Eat smaller, more frequent meals.
• For diarrhea: Stay well hydrated. Eat bland foods like rice, bananas, and toast. If it persists more than a few days, call your doctor.
• For headache: Drink plenty of water. Rest in a quiet, dark room. Ask your doctor if acetaminophen is safe to take with your other medications.
• For dizziness: Stand up slowly from sitting or lying positions. Avoid driving if you feel dizzy.
• For fatigue: Get adequate rest. Light exercise may actually help improve energy levels.

Drug Interactions That Can Worsen Side Effects

Many of Itraconazole's most serious side effects are made worse by drug interactions. Itraconazole is a strong inhibitor of the CYP3A4 enzyme, which means it can increase levels of many other medications in your body. For a detailed list of what to avoid, read our complete guide on Itraconazole drug interactions.

Always tell your doctor and pharmacist about every medication you take, including over-the-counter drugs, supplements, and herbal products.

What to Tell Your Doctor Before Starting Itraconazole

To minimize your risk of side effects, make sure your doctor knows if you:

• Have or have had heart failure or other heart problems
• Have liver disease or a history of liver problems
• Have kidney disease
• Have cystic fibrosis (may affect how well Itraconazole is absorbed)
• Are pregnant, planning to become pregnant, or breastfeeding
• Take any medications that might interact with Itraconazole

If You're Having Trouble With Side Effects

Don't stop taking Itraconazole without talking to your doctor first. Stopping antifungal treatment early can allow the infection to come back or get worse. If side effects are bothering you, your doctor may be able to:

• Adjust your dose
• Switch you to a different formulation (capsules vs. oral solution)
• Try pulse therapy instead of continuous dosing
• Recommend an alternative antifungal medication

For more information about finding Itraconazole at your pharmacy, check our guides on finding Itraconazole in stock and saving money on your prescription. If you're facing supply issues, learn about the current Itraconazole shortage situation and why it can be hard to find.

Healthcare providers can find clinical guidance in our provider articles on managing Itraconazole shortages, helping patients find Itraconazole, and helping patients save on costs.

Bottom Line

Most people tolerate Itraconazole well, with nausea and diarrhea being the most common complaints. The serious side effects — heart failure, liver damage, and severe skin reactions — are rare but important to watch for. Know the warning signs, keep your follow-up appointments, and never hesitate to call your doctor if something doesn't feel right.