If you have any questions about this information, you can contact the Drugs in Breastmilk team through their Facebook page or on druginformation@breastfeedingnetwork.org.uk.

Constipation is defined as difficulty in passing bowel motions, which may be described as hard, infrequent or changed in volume and/or consistency.  Frequently, constipation is caused by a change in diet or by medication. Individual experiences of bowel motions are subjective but constipation affects many people at some time in their lives. It is common towards the end of pregnancy and following pain relief for childbirth when it may be particularly difficult due to perineal stitches.  For further information see the patient.info page on constipation.

The first remedy should be to increase fruit, vegetable and fibre intake, along with additional water consumption. Exercise may also help to relieve symptoms. 

If you are taking opioid-based pain relief medication (e.g. dihydrocodeine, co-dydramol, tramadol or morphine), this may cause constipation. (Codeine is not recommended when breastfeeding for other safety reasons- see our factsheet on codeine for more information). If possible, stop the opioid-based pain relief and use an alternative such as paracetamol, ibuprofen or another NSAID (see our factsheet on pain relief for more information). If your opioid pain relief is prescribed, discuss this with your doctor first. If it is not possible to switch to a non-opioid alternative, a laxative can be taken to alleviate constipation.

Where a medication is required to resolve constipation during breastfeeding, osmotic or bulk laxatives are preferable, at least initially, to stimulant laxatives. Bulk Laxatives are particularly useful where stools are small and hard. However there may be a delay of up to 72 hours before they exert their full effect. Bulk laxatives absorb water within the gut and swell to produce a greater volume of soft stool which is easier to pass e.g. Fybogel^®, Regulan^®, Isogel^®, Normacol^®. Absorption of bulk laxatives is minimal and they can all be used during breastfeeding.

Osmotic laxatives work by increasing the amount of fluid in the large bowel. These also have a delay in action but it is generally shorter than bulk laxatives. They help to produce softer bowel movements, which are easier to pass. E.g. Magnesium Hydroxide, Magnesium Sulphate, Lactulose, Movicol^®. Passage of osmotic laxatives into breastmilk is low and they can all be used during breastfeeding.

Stimulant laxatives should not be used routinely by anyone as they can lead to a reliance on their action. They may cause evacuation of all bowel contents, which then need to re-build before a regular normal bowel action is resumed. They are however, useful for occasional use.  They have a more rapid onset of action than bulk or osmotic laxatives, and are usually given at night to help produce a bowel motion the following morning e.g. Senna (Senokot^®, Ex Lax^®) Bisacodyl (Dulcolax^®), Sodium Picosulphate (Laxoberal^®, Picolax^®).

Side effects in breastfeeding infants have not been proven although loose bowel motions have been reported even with undetectable levels of senna in breastmilk. 

Bibliography

• British National Formulary
• Hale T. W Medications in Mothers Milk
• Jones W Breastfeeding and Medication 2018 Routledge
• Lactmed website https://www.ncbi.nlm.nih.gov/books/NBK501922/
• Martindale, the Extra Pharmacopia 2007

©The Breastfeeding Network. Last full review Sept 2019. Last amended February 2026.