acyclovir vs molnupiravir
Side-by-side comparison of acyclovir and molnupiravir Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Zovirax
Lagevrio
Acyclovir is an antiviral medicine. It is used to treat infections caused by certain viruses.
Lagevrio contains molnupiravir, an antiviral medicine. It is used to treat COVID-19 in adults.
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.
Lagevrio treats mild-to-moderate COVID-19 in adults. You must be at high risk of getting very sick, needing hospitalization, or dying from COVID-19. You can only use this medicine if other approved COVID-19 treatments are not available or are not right for you.
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.
Lagevrio stops the COVID-19 virus from multiplying in your body. It does this by interfering with how the virus makes copies of itself. This helps your body fight off the infection.
- • Malaise (feeling unwell)
- • Nausea
- • Diarrhea
- • Diarrhea
- • Nausea
- • Dizziness
- 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
- Product Use Issue 709
- No Adverse Event 623
- Covid-19 476
- Wrong Technique In Product Usage Process 390
- Product Use In Unapproved Indication 308
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.
Lagevrio is only for adults with mild-to-moderate COVID-19 who are at high risk of severe illness and when other treatments aren't suitable. Tell your doctor if you are pregnant or plan to become pregnant. Lagevrio may harm your unborn baby. Females who can get pregnant should use birth control during treatment and for 4 days after the last dose. Males who can get someone pregnant should use birth control during treatment and for 3 months after the last dose.
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.
Lagevrio may harm your unborn baby. If you are pregnant, talk to your doctor about the risks and benefits of taking Lagevrio. There is a pregnancy registry to track outcomes in people who take Lagevrio while pregnant. You can find it at https://covid-pr.pregistry.com or call 1-800-616-3791.
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How to Read This acyclovir vs molnupiravir Comparison
acyclovir is classified in the Antiviral (Nucleoside Analog) drug class, while molnupiravir sits within the Nucleoside Analog (Antiviral) 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 molnupiravir has 2,506. 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 molnupiravir — 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.