Molnupiravir
Other antivirals
Other antiviralsPregnancy: avoid
Avoid in pregnancy. Not recommended because it may harm the fetus. Contraception is used during treatment and afterwards, by women and by men.
An oral COVID-19 antiviral that makes the coronavirus copy its RNA with many errors. It is a reserve option when other treatments cannot be used.
Quick facts
- Group
- Other antivirals
- Target
- SARS-CoV-2 RNA-dependent RNA polymerase (nsp12)
- Used for
- Mild to moderate COVID-19
- Key effects
- Diarrhoea · Nausea · Dizziness
- Monitor
- Pregnancy test when relevant
- ATC
- J05AB18
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows the SARS-CoV-2 polymerase with molnupiravir's active form (NHC) built into the template RNA strand, paired with adenine.
Molnupiravir is a prodrug of the nucleoside analogue N4-hydroxycytidine (NHC). Inside cells NHC triphosphate is used by the viral RNA polymerase in place of cytidine or uridine. Once in the RNA, NHC can pair with either guanine or adenine, so later copies collect mutations until the virus can no longer replicate (lethal mutagenesis).
- Molnupiravir is converted to NHC triphosphate
- The viral polymerase builds NHC into its RNA
- NHC pairs with G or A, causing errors
- Errors pile up and the virus fails
Indications
- Mild to moderate COVID-19 in adults at high risk of severe disease when other treatments are not available or suitable COVID-19 →
Adverse effects
Common
- Diarrhoea
- Nausea
- Dizziness
Contraindications
- Children and adolescents under eighteen
- Hypersensitivity to molnupiravir
Key interactions
- Other medicines
- No important interactions are listed; all medicines are still reviewed
What is monitored
- Pregnancy test when relevant
- Symptoms of COVID-19 progression
Administration and safety
- Oral capsules swallowed whole, started early after symptoms begin
- The full short course is completed
Pregnancy and breastfeeding
Avoid in pregnancy. Not recommended because it may harm the fetus. Contraception is used during treatment and afterwards, by women and by men.
Nursing care
- Check pregnancy status before starting
- Teach reliable contraception during and after treatment (women and men)
- Advise against breastfeeding during treatment and for a few days after
- Teach to seek care if breathing worsens
Pharmacokinetics
- Absorption
- Oral capsules, with or without food
- Metabolism
- Hydrolysed to NHC, which is phosphorylated in cells
Test yourself
Think of the answer, then tap the question to see it.
What is the mechanism of molnupiravir?
Lethal mutagenesis: its active form NHC is built into viral RNA and causes errors in later copies.
Why is molnupiravir not recommended in pregnancy?
It may harm the fetus.
Is molnupiravir used in children?
No. It may affect bone and cartilage growth and is not used under eighteen years.
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: Molnupiravir: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); SARS-CoV-2 RdRp with Molnupiravir/ NHC in the template strand base-paired with A (RCSB Protein Data Bank, 2021); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.