acyclovir vs voriconazole
Side-by-side comparison of acyclovir and voriconazole Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Zovirax
Vfend
Acyclovir is an antiviral medicine. It is used to treat infections caused by certain viruses.
Voriconazole (Vfend) is an antifungal medicine. It is used to treat serious fungal infections in adults and children 2 years and older.
Acyclovir is used to treat shingles, which is caused by herpes zoster. It also treats genital herpes, both the first time you have it and when it comes back. Acyclovir can also treat chickenpox.
This medicine treats several types of fungal infections. It is used for invasive aspergillosis, a lung infection. It also treats candidemia (a blood infection) and other Candida infections in the skin, abdomen, kidney, bladder, and wounds. Voriconazole can also treat esophageal candidiasis (a throat infection) and serious infections caused by Scedosporium and Fusarium fungi.
Acyclovir stops the virus from growing and spreading. It does this by interfering with the virus's ability to make copies of itself. This helps your body fight off the infection.
Voriconazole belongs to a class of drugs called azole antifungals. It works by stopping the growth of fungi. It does this by interfering with the production of the fungal cell membrane.
- • Malaise (feeling unwell)
- • Nausea
- • Diarrhea
- • Visual disturbances
- • Fever
- • Nausea
- • Rash
- • Vomiting
- Tiredness 7,612
- Diarrhea 7,064
- Using the medicine for something it's not approved for 5,797
- Lung infection 5,474
- Feeling sick to your stomach 5,330
- The medicine is not working 4,098
- Using the medicine for a condition it is not approved for 2,342
- The medicine is interacting with another medicine 2,315
- Death 1,460
- Fever 1,411
Acyclovir can cause nervous system problems, especially in older adults or people with kidney problems. Tell your doctor if you have kidney problems before taking this medicine.
Voriconazole can cause serious liver problems. Your doctor will check your liver function with blood tests before and during treatment. This medicine can also cause heart rhythm problems. Make sure your potassium, magnesium, and calcium levels are normal before starting. Voriconazole can also cause severe skin reactions and make you sensitive to sunlight. Avoid sunlight and wear protective clothing. This medicine can harm an unborn baby, so women who can get pregnant should use effective birth control.
Tell your doctor if you are pregnant or plan to become pregnant. It is not known if acyclovir will harm an unborn baby. Talk to your doctor about the risks and benefits of taking acyclovir while breastfeeding.
Voriconazole can cause harm to an unborn baby. If you are pregnant or could become pregnant, talk to your doctor. It is not known if voriconazole passes into breast milk. Talk to your doctor about the risks and benefits of breastfeeding while taking this medicine.
Also Compare — Nearby Drugs
Compare acyclovir with
Compare voriconazole with
How to Read This acyclovir vs voriconazole Comparison
acyclovir is classified in the Antiviral (Nucleoside Analog) drug class, while voriconazole sits within the Azole Antifungal class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. 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, acyclovir has 31,277 submissions while voriconazole has 11,626. 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 substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between acyclovir and voriconazole — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.