Posaconazole: The Basics

Posaconazole is a prescription antifungal medication sold under the brand name Noxafil. It belongs to a class of drugs called triazole antifungals and is manufactured by Merck & Co. Posaconazole is used to prevent and treat serious fungal infections, particularly in patients with weakened immune systems.

Unlike common antifungals you might pick up at the drugstore, Posaconazole is a powerful, prescription-only medication typically prescribed by specialists like infectious disease doctors, oncologists, and transplant physicians. If you've been prescribed Posaconazole, it's because your doctor believes you're at risk for — or already fighting — a potentially life-threatening fungal infection.

What Is Posaconazole Used For?

FDA-Approved Uses

Posaconazole is FDA-approved for two primary purposes:

1. Prevention (Prophylaxis) of Invasive Fungal Infections — This is the most common reason Posaconazole is prescribed. It's used to prevent invasive Aspergillus and Candida infections in patients who are severely immunocompromised, including:
   • Hematopoietic stem cell transplant (bone marrow transplant) recipients with graft-versus-host disease (GVHD)
   • Patients with blood cancers (leukemia, lymphoma) who have prolonged neutropenia from chemotherapy
2. Treatment of Oropharyngeal Candidiasis — Posaconazole can treat oral thrush (Candida infection of the mouth and throat), including cases that don't respond to other antifungals like Itraconazole or Fluconazole.

Common Off-Label Uses

Doctors also prescribe Posaconazole for conditions beyond its official FDA indications, including:

• Invasive aspergillosis (as salvage therapy when other treatments fail)
• Mucormycosis (zygomycosis) — a rare but aggressive fungal infection
• Fusariosis
• Coccidioidomycosis (valley fever)
• Antifungal prophylaxis in solid organ transplant recipients

To understand how Posaconazole fights these infections at a cellular level, check out our mechanism of action explainer.

How Is Posaconazole Available?

Posaconazole comes in several forms as of 2026:

• Delayed-Release Tablets (100 mg) — The most common oral form. Swallow whole with food; do not crush, chew, or divide.
• Intravenous (IV) Injection (300 mg vial) — For patients who can't take oral medications. Given through a central venous line over about 90 minutes.
• PowderMix Delayed-Release Oral Suspension — A newer formulation developed to replace the original immediate-release oral suspension, which was removed from the market in 2024.

Important: The delayed-release tablets and the oral suspension are NOT interchangeable — they have different dosing requirements. Always take the exact form your doctor prescribed.

Posaconazole Dosage Guide

Dosing depends on what Posaconazole is being used for and which formulation you're taking:

For Prevention of Invasive Fungal Infections (Tablets)

• Day 1 (Loading Dose): 300 mg (three 100 mg tablets) twice daily
• Day 2 and Beyond: 300 mg (three 100 mg tablets) once daily

For Prevention of Invasive Fungal Infections (IV)

• Day 1 (Loading Dose): 300 mg IV twice daily
• Day 2 and Beyond: 300 mg IV once daily

For Oropharyngeal Candidiasis (Tablets)

• Day 1 (Loading Dose): 300 mg twice daily
• Days 2–13: 300 mg once daily
• Total treatment: 14 days (duration may be adjusted based on clinical response)

Duration of Treatment

For prophylaxis, you'll typically continue taking Posaconazole until your immune system recovers — for example, until your neutrophil counts return to normal after chemotherapy, or until your graft-versus-host disease is controlled. Your doctor will determine when it's safe to stop.

How to Take Posaconazole Correctly

Getting the most out of Posaconazole requires taking it properly:

• Take with food — This is critical for absorption, especially with the tablet form. A meal or nutritional supplement improves how much medication your body absorbs.
• Swallow tablets whole — Do not crush, chew, or break the delayed-release tablets.
• Take at the same time each day — Consistency helps maintain steady drug levels in your blood.
• Don't skip doses — Missing doses can allow fungal levels to rise. If you miss a dose, take it as soon as you remember (unless it's almost time for your next dose).
• IV administration — If you're receiving Posaconazole IV, it's typically given through a central venous catheter over approximately 90 minutes. A peripheral line may be used for a single dose only.

Important Safety Information

Who Should NOT Take Posaconazole

Posaconazole is contraindicated (should not be used) in patients who:

• Have a known allergy to Posaconazole or other azole antifungals
• Are taking sirolimus, ergot alkaloids, pimozide, quinidine, or certain statin medications (Atorvastatin, Lovastatin, Simvastatin)
• Are taking QTc-prolonging drugs that are metabolized by CYP3A4

For a complete rundown of medications to avoid, read our drug interactions guide.

Monitoring Requirements

While taking Posaconazole, your doctor will monitor:

• Liver function tests (to watch for hepatotoxicity)
• Electrolytes, especially potassium and magnesium
• EKG (to check heart rhythm)
• Drug levels (therapeutic drug monitoring to ensure adequate absorption)

Special Populations

• Pregnancy: Posaconazole is Category C — animal studies showed skeletal malformations. Use only if the benefit clearly outweighs the risk.
• Children: Delayed-release tablets and IV are approved for patients 2 years and older weighing more than 40 kg for prophylaxis.
• Kidney Problems: The IV formulation contains a vehicle (SBECD) that can accumulate in patients with moderate-to-severe kidney impairment. The tablet form doesn't have this issue.
• Liver Problems: No dose adjustment is typically needed, but closer monitoring for liver toxicity is recommended.

Common Side Effects

The most frequently reported side effects include diarrhea, nausea, vomiting, fever, headache, cough, low potassium, elevated liver enzymes, rash, and fatigue. Most are manageable, but some require medical attention. Read our detailed side effects guide to know what to watch for and when to call your doctor.

Generic vs. Brand: Noxafil vs. Posaconazole

Noxafil is the brand name, while Posaconazole is the generic. Generic Posaconazole tablets are significantly less expensive — approximately $187-$250 for 90 tablets with a coupon, compared to $4,500+ for brand-name Noxafil. Your doctor and pharmacist can help determine whether the generic is appropriate for you (in most cases, it is).

For more on pricing and savings, see our guide to saving money on Posaconazole.

Finding Posaconazole

Because it's a specialty medication, Posaconazole isn't available at every pharmacy. If you're having trouble finding it, check out our guides on checking pharmacy stock and finding Posaconazole near you. You can also search medfinder.com to locate pharmacies with Posaconazole in stock in your area.

The Bottom Line

Posaconazole is a critical antifungal medication for immunocompromised patients at risk of life-threatening fungal infections. It's effective, well-studied, and available in multiple formulations — but it requires careful dosing, monitoring, and attention to drug interactions. Work closely with your specialist, take it exactly as prescribed with food, and stay on top of your lab work. If you have questions about your Posaconazole therapy, don't hesitate to ask your healthcare team.