Tecovirimat
Other antivirals
Other antivirals
An orthopoxvirus antiviral developed for smallpox preparedness and used for severe mpox. It stops the virus spreading from cell to cell.
Quick facts
- Group
- Other antivirals
- Target
- Orthopoxvirus envelope protein F13 (VP37)
- Used for
- Severe mpox or mpox
- Key effects
- Headache · Nausea and abdominal pain · Diarrhoea
- Monitor
- Lesion progression and new lesions · Kidney function
- ATC
- J05AX24
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows tecovirimat bound to the vaccinia virus F13 protein (A295E variant); mpox F13 is closely related.
Tecovirimat targets the F13 protein (VP37), encoded by the F13L gene of orthopoxviruses. It blocks VP37 from interacting with host cell proteins needed to wrap virions in an extra envelope. Without this envelope, the virus cannot leave the cell to infect neighbours, so the spread from cell to cell is reduced. A single mutation in F13 can cause resistance, seen mainly after long treatment in advanced HIV.
- Tecovirimat binds the viral F13 (VP37) protein
- VP37 cannot work with host proteins
- Virions are not wrapped for release
- Spread to neighbouring cells drops
Indications
- Severe mpox or mpox in people at high risk (e.g. severe immunocompromise), under expanded-access protocols Mpox →
- Stockpiled for smallpox preparedness
Adverse effects
Common
- Headache
- Nausea and abdominal pain
- Diarrhoea
- Itching
Contraindications
- Intravenous form in severe kidney impairment, unless oral absorption is not possible
- Hypersensitivity to tecovirimat
Key interactions
- Rilpivirine
- Tecovirimat may lower its levels
- Repaglinide
- Tecovirimat may raise its levels (risk of low blood sugar)
- Midazolam
- Tecovirimat may lower its levels
What is monitored
- Lesion progression and new lesions
- Kidney function with the intravenous form
- Blood glucose with repaglinide
Administration and safety
- Oral capsules are taken with a fatty meal
- Intravenous tecovirimat is kept for people who cannot eat or absorb, or have disseminated disease
- Given through public health protocols that record use and outcomes
Pregnancy and breastfeeding
Considered likely safe in pregnancy and breastfeeding in public health guidance, but human data are limited.
Nursing care
- Check that each oral dose is given with an adequate meal
- Check kidney function before the intravenous form
- Report new lesions after a week of treatment (possible resistance)
- Teach isolation and lesion care to limit spread
Pharmacokinetics
- Absorption
- Oral capsules need a fatty meal for good absorption; an intravenous form exists
- Elimination
- The intravenous excipient (a cyclodextrin) is cleared by the kidneys
Test yourself
Think of the answer, then tap the question to see it.
Which viral protein does tecovirimat target?
F13 (VP37), needed to wrap orthopoxvirus virions for release.
Why is oral tecovirimat taken with a fatty meal?
Fat greatly improves its absorption.
Which antiretroviral may lose effect with tecovirimat?
Rilpivirine, whose levels may fall.
Connections
← Back to the class: Other antivirals
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Interim Clinical Treatment Considerations for Severe Manifestations of Mpox — United States, February 2023 (Centers for Disease Control and Prevention (MMWR), 2023); Structure of the F13 protein (A295E mutant) of Vaccinia virus in complex with tecovirimat (RCSB Protein Data Bank, 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.