Like all medicines, molnupiravir can cause side effects in some people, although not everyone gets them.
Common side effects
These common side effects of molnupiravir happen in more than 1 in 100 people. There are things you can do to help cope with them:
Feeling dizzy
If molnupiravir makes you feel dizzy, stop what you're doing and sit or lie down until you feel better. Do not drive, ride a bike, or use tools or machinery if you feel dizzy.
Headaches
Make sure you rest and drink plenty of fluids. Try not to drink too much alcohol. Ask your pharmacist to recommend a painkiller. Speak to your doctor if this does not help or your headaches are severe.
Diarrhoea
Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take the combined pill or progestogen-only pill and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice
Feeling or being sick (nausea or vomiting)
Stick to simple meals and do not eat rich or spicy food. It might help to take your medicine after you have eaten.
If you're being sick, try small, frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
If you take the combined pill or progestogen-only pill and you're being sick, your contraceptive pills may not protect you from pregnancy. Check the pill packet to find out what to do.
Serious side effects
There are no known serious side effects with molnupiravir.
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to molnupiravir.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Reporting side effects
You can report any suspected side effect using the Yellow Card safety scheme.
Visit the Yellow Card website for more information about reporting side effects.