This NHS content is written for people in England. Medicine names, availability, prescribing and services may differ in other countries.
Cefalexin and pregnancy
You can take cefalexin at any stage during pregnancy. There's no evidence that it causes harm to the baby.
It's important to treat infection during pregnancy as there's a risk that it could make you unwell if left untreated.
Cefalexin and breastfeedingIt's OK for you to take cefalexin while breastfeeding.
Only tiny amounts of cefalexin get into breast milk, so it does not normally cause any side effects in your baby. However, it has caused diarrhoea in a few infants.
It's important to treat an infection while you're breastfeeding as there's a risk that it could make you unwell if left untreated.
Talk to your health visitor, midwife, doctor or pharmacist as soon as possible if you have any concerns, including if your baby:
- is not feeding as well as usual
- has sickness or diarrhoea
- has oral thrush (a fungal infection in their mouth) or a skin rash
There's no evidence to suggest that cefalexin affects fertility in men or women.
Meds New IA (H2) - Pregnancy non-urgent care card
Tell your doctor if you're:
- trying to get pregnant
- pregnant
- breastfeeding
View the original NHS website page ↗. Refreshed 19 August 2026.
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