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Pregnancy, breastfeeding and fertility while taking sulfasalazine

NHS medicines information on sulfasalazine and whether you can take it while pregnant or breastfeeding.

About this information

This NHS content is written for people in England. Medicine names, availability, prescribing and services may differ in other countries.

Sulfasalazine and pregnancy

There are no concerns that taking sulfasalazine in pregnancy can harm your baby.

Sulfasalazine can affect your folate levels. To help with this, take high dose folic acid (5mg a day), particularly in the 3 months before you start trying to get pregnant and during the first 12 weeks of pregnancy.

You can continue taking folic acid throughout your pregnancy.

Talk to your doctor or midwife if you're trying to get pregnant, or as soon as you become pregnant, so that high dose folic acid can be prescribed.

Sulfasalazine and breastfeeding

If your baby is healthy, you may be able to take or use sulfasalazine while breastfeeding. Your doctor can talk with you about your options.

It's important to keep treating your condition to keep you well. Breastfeeding will also benefit both you and your baby.

Small amounts of sulfasalazine pass into breast milk and it should not cause any side effects in your baby, although there have been some rare cases of diarrhoea in babies. It's important to keep monitoring your baby if you're taking any medicine while breastfeeding.

Contact your healthcare professional or call 111 as soon as possible if you notice that your baby:

  • has diarrhoea
  • is being sick (vomiting)
  • has a rash
  • is not sleeping as well as usual, or being irritable
  • has signs of jaundice – yellowing of the whites of the eyes and the skin (this may be less obvious on brown or black skin), dark pee and pale poo

If your baby has any symptoms that are not listed, or if you're worried about them, you can also call 111 or contact any healthcare professional.

Carry on taking the medicine, and keep breastfeeding as usual until you've got advice about your baby's symptoms.

View the original NHS website page ↗. Refreshed 19 August 2026.

Licensed under the Open Government Licence v3.0 ↗. MyPHU is independent and is not endorsed by the NHS.

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