isavuconazonium vs posaconazole

PlainMeds reviewed this comparison against our methodology in August 2026. It places FDA and CMS record fields side by side, without recommending either medication.

Side-by-side comparison of isavuconazonium and posaconazole. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.

Drug Class
isavuconazonium Azole Antifungal
posaconazole Azole Antifungal
Type
isavuconazonium Prescription
posaconazole Prescription
Summary
isavuconazonium

Cresemba is an antifungal medicine. It is used to treat serious fungal infections in adults and children.

posaconazole

Posaconazole is an antifungal medicine. It helps prevent certain fungal infections in people with weakened immune systems.

What It Treats
isavuconazonium

Cresemba treats invasive aspergillosis and invasive mucormycosis. These are serious infections caused by different types of fungi. Cresemba is available as an injection for those 1 year and older. Cresemba capsules are for those 6 years and older who weigh at least 35 pounds.

posaconazole

Posaconazole prevents Aspergillus and Candida infections. You may need this medicine if you have a high risk of getting these infections. This often includes people who had a stem cell transplant or have certain blood cancers and are on chemotherapy.

How It Works
isavuconazonium

Cresemba belongs to a class of drugs called azole antifungals. It works by stopping the growth of the fungi. This helps your body fight off the infection.

posaconazole

Posaconazole belongs to a class of drugs called azole antifungals. It works by stopping the growth of fungi. This helps your body fight off the infection.

Common Side Effects
isavuconazonium
  • Nausea
  • Vomiting
  • Diarrhea
  • Headache
  • Changes in liver tests
posaconazole
  • Diarrhea
  • Nausea
  • Fever
  • Vomiting
  • Headache
FAERS Reports
isavuconazonium
  • Death 310
  • Nausea 143
  • Febrile Neutropenia 135
  • Pyrexia 125
  • Pneumonia 114
posaconazole
  • Febrile Neutropenia 1,017
  • Drug Interaction 930
  • Death 928
  • Pyrexia 850
  • Neutropenia 705
Serious Warnings
isavuconazonium

Cresemba can cause serious liver problems. Your doctor will check your liver function before and during treatment. Cresemba can also cause allergic reactions. Tell your doctor right away if you have any signs of a reaction, like trouble breathing or skin rash. Cresemba can harm an unborn baby. Use birth control while taking this medicine.

posaconazole

Posaconazole can interact with many other medicines. It can cause heart rhythm problems (QT prolongation). It can also cause liver problems. Tell your doctor about all the medicines you take.

Pregnancy
isavuconazonium

Cresemba can harm your unborn baby. Tell your doctor if you are pregnant or plan to become pregnant. Do not breastfeed while taking Cresemba.

posaconazole

Posaconazole may harm an unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if posaconazole passes into breast milk, so talk to your doctor if you are breastfeeding.

Also Compare, Nearby Drugs

How to Read This isavuconazonium vs posaconazole Comparison

isavuconazonium is classified in the Azole Antifungal drug class, while posaconazole sits within the Azole Antifungal class. Because both drugs share the same classification, they are often considered interchangeable in theory, but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.

Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, isavuconazonium has 827 submissions while posaconazole has 4,430. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.

A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for isavuconazonium or posaconazole.

Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.