Prescription medication · VP37 Inhibitor (Antiviral)
tecovirimat
Also sold as Tpoxx. Tpoxx is used to treat smallpox in adults and children who weigh at least 7 pounds.
Data updated 2026-05-15
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tecovirimat (Tpoxx) is a prescription VP37 Inhibitor (Antiviral). Tpoxx is used to treat smallpox in adults and children who weigh at least 7 pounds.
Tpoxx is an antiviral medicine used to treat smallpox. It works by stopping the smallpox virus from spreading in your body.
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What it does
Tpoxx is used to treat smallpox in adults and children who weigh at least 7 pounds.
Common side effects
Headache, Nausea, Stomach pain
Key warnings
If you have kidney problems, use the injection with caution.
The sections below are summarized in plain English from tecovirimat's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
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.
Serious Warnings
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.
Known Drug Interactions
7.3 Drugs Without Clinically Significant Interactions With TPOXX Based on a drug interaction study, no clinically significant drug interactions have been observed when TPOXX is co-administered with bupropion, flurbiprofen, or omeprazole [see Clinical Pharmacology ( 12.3 )] .
Mechanism: There are no significant interactions between these two drugs based on medical studies.
7.3 Drugs Without Clinically Significant Interactions With TPOXX Based on a drug interaction study, no clinically significant drug interactions have been observed when TPOXX is co-administered with bupropion, flurbiprofen, or omeprazole [see Clinical Pharmacology ( 12.3 )] .
Mechanism: Research shows that taking these two drugs together does not cause any meaningful changes in how they work.
CNS Depressant: Midazolam b ↓ midazolam Monitor for effectiveness of midazolam.
Mechanism: Tecovirimat causes the body to process midazolam faster, which lowers the amount of medicine in your system.
Concomitant Drug Class: Drug Name Effect on Concentration a Clinical Effect/Recommendation Blood Glucose-Lowering Agent: Repaglinide b ↑ repaglinide Monitor blood glucose and monitor for hypoglycemic symptoms in patients when TPOXX is co-administered with repaglinide [see Warnings and Precautions ( 5.1 )] .
Mechanism: Tecovirimat increases the amount of repaglinide in your blood, which can cause your blood sugar to drop too low.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
Common Questions
Can I take Tpoxx on an empty stomach?
How long will I need to take Tpoxx?
What should I do if I vomit after taking a dose of Tpoxx?
Can Tpoxx interact with other medications I am taking?
Will Tpoxx prevent me from spreading smallpox to others?
What if I have trouble swallowing capsules?
Can I get a smallpox vaccine while taking Tpoxx?
What are the ingredients in Tpoxx capsules?
What should I do if I experience side effects while taking Tpoxx?
Is Tpoxx a cure for smallpox?
What are the common side effects of tecovirimat?
Does tecovirimat interact with other medications?
What drug class is tecovirimat?
What pregnancy or breastfeeding source fields are listed for tecovirimat?
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What the FDA Data Shows for tecovirimat
The FDA label for tecovirimat (sold under brand names such as Tpoxx) classifies it as a prescription-only medication in the VP37 Inhibitor (Antiviral) class. Tpoxx is used to treat smallpox in adults and children who weigh at least 7 pounds. Official labeling lists 5 commonly reported side effects, including Headache, Nausea, Stomach pain.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. Voluntary reports accumulate over the lifetime of a drug and reflect wide-ranging clinical use. The database also lists 4 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. Acquisition-cost data is surveyed weekly by CMS and updated as manufacturers report changes.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.
Last updated: December 31, 2025
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages