acyclovir vs tecovirimat
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 tecovirimat. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Zovirax
Tpoxx
Acyclovir is an antiviral medicine. It is used to treat infections caused by certain viruses.
Tpoxx is an antiviral medicine used to treat smallpox. It works by stopping the smallpox virus from spreading in your body.
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.
Tpoxx is used to treat smallpox in adults and children who weigh at least 7 pounds. Smallpox is caused by the variola virus. Tpoxx may not work as well if you have a weak immune system.
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.
Tpoxx blocks a protein called VP37 on the smallpox virus. This protein helps the virus to spread. By blocking VP37, Tpoxx stops the virus from wrapping itself and infecting other cells.
- • Malaise (feeling unwell)
- • Nausea
- • Diarrhea
- • Headache
- • Nausea
- • Stomach pain
- • Vomiting
- • Reactions where the injection was given
- Fatigue 7,612
- Diarrhoea 7,064
- Pneumonia 5,471
- Nausea 5,328
- Pyrexia 4,719
No adverse event reports.
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.
If you have kidney problems, use the injection with caution. If you have severe kidney problems (creatinine clearance below 30 mL/min), you should not use the Tpoxx injection. When taking Tpoxx with repaglinide, monitor your blood sugar for hypoglycemia.
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.
There is not enough information about Tpoxx use in pregnant women to know if it is safe. Breastfeeding is not recommended if you have smallpox because the virus can spread to your baby through breast milk.
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How to Read This acyclovir vs tecovirimat Comparison
acyclovir is classified in the Antiviral (Nucleoside Analog) drug class, while tecovirimat sits within the VP37 Inhibitor (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 30,194 submissions while tecovirimat has 0. 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 tecovirimat.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.