acyclovir vs ganciclovir
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 acyclovir and ganciclovir. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Zovirax
Cytovene
Acyclovir is an antiviral medicine. It is used to treat infections caused by certain viruses.
Ganciclovir injection is an antiviral medicine. It helps treat and prevent cytomegalovirus (CMV) infections.
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 CMV retinitis, an eye infection, in people with weak immune systems, including those with AIDS. It also prevents CMV disease in adults who have had organ transplants and are at risk for CMV.
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.
Ganciclovir stops CMV from multiplying. It does this by blocking a key enzyme the virus needs to make copies of itself. This helps your body fight off the CMV infection.
- • Malaise (feeling unwell)
- • Nausea
- • Diarrhea
- • Fever
- • Diarrhea
- • Low white blood cell count
- • Nausea
- • Anemia (low red blood cell count)
- Fatigue 7,612
- Diarrhoea 7,064
- Pneumonia 5,471
- Nausea 5,328
- Pyrexia 4,719
- Cytomegalovirus Infection 1,170
- Drug Resistance 653
- Pyrexia 590
- Neutropenia 503
- Pancytopenia 503
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.
This drug can cause serious side effects. It can lower blood cell counts, possibly leading to severe infections or bleeding. It may also harm fertility in both men and women. Ganciclovir can cause birth defects and may increase your risk of cancer. Talk to your doctor about these risks.
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.
Ganciclovir can harm your unborn baby. Do not get pregnant while taking this medicine. Talk to your doctor about birth control. Breastfeeding is not recommended while using this medicine.
Also Compare, Nearby Drugs
Compare acyclovir with
Compare ganciclovir with
How to Read This acyclovir vs ganciclovir Comparison
acyclovir is classified in the Antiviral (Nucleoside Analog) drug class, while ganciclovir sits within the Antiviral (Nucleoside Analog) 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, acyclovir has 30,194 submissions while ganciclovir has 3,419. 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 acyclovir or ganciclovir.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.