Medicines while breastfeeding: UK advice explained

Specialist pharmacy guidance for the NHS is blunt on this point. Most medicines can be taken while breastfeeding, and the risks that exist can often be reduced by choosing a particular medicine or route and by watching how the baby is feeding. A prescriber who says "stop breastfeeding while you take this" has not necessarily weighed up the benefits of feeding against the small amount of drug that reaches the milk.

Stopping breastfeeding is described in the same guidance as a decision with its own downsides for both mother and baby. For many conditions the sensible question is therefore which medicine is best for the two of them, not whether feeding must end.

Pharmacists look at a few properties of a medicine when judging milk transfer, and understanding them helps make sense of the advice you are given.

• High protein binding and a large molecule both tend to limit how much passes into milk.

• A long half-life raises the risk of build-up in the baby, particularly a newborn whose body clears medicines slowly.

• Low oral bioavailability means that even when some medicine is swallowed in milk, little is absorbed by the baby.

• Route matters: inhaled or topical treatments usually expose the baby less than tablets or injections.

• Medicines already used therapeutically in infants are generally more reassuring than those never studied in babies.

Timing doses around feeds is often suggested but, as the guidance notes, it is frequently impractical. Pharmacists more often advise simple observation: does the baby wake normally for feeds, is feeding going well, and is weight gain progressing as expected. Unusual drowsiness, poor feeding or irritability after a new medicine is worth raising with the health visitor, midwife, GP or pharmacist promptly.

Newborns and premature babies are the group where more caution applies, because their livers and kidneys are still maturing. Advice written for healthy full-term infants should not be applied automatically to a baby who was born early or is unwell.

Painkillers are the commonest query. NHS guidance on ibuprofen says paracetamol is usually the best painkiller for a breastfeeding mother, though ibuprofen may sometimes be suitable, and that a healthcare professional should be consulted first. The NHS page on anti-inflammatory painkillers also says they are not usually recommended when pregnant or breastfeeding and that a pharmacist can help find a suitable alternative.

The Specialist Pharmacy Service publishes dedicated pages for several groups where mothers frequently worry, including antihistamines, codeine-type painkillers and lipid-lowering medicines. Codeine, dihydrocodeine and tramadol get their own article because the balance of risk is more delicate than for simple painkillers. Do not rely on a quick online answer for these; ask for a review of the specific product.

Some people ask for a medicine to dry up milk. The MHRA has said bromocriptine should be used to suppress lactation only when medically indicated, such as after the loss of a baby or in some cases of HIV infection, and not routinely for breast pain or engorgement, which usually respond to non-drug measures such as cold compresses and firm support. Blood pressure needs monitoring because of reported hypertension, and the drug should not be used in uncontrolled high blood pressure or pre-eclampsia. Cabergoline is described as the preferred option where a medicine is needed.

A community pharmacist is the quickest route for over-the-counter and minor-illness questions. The Breastfeeding Network publishes factsheets from its pharmacist team covering well over 80 topics, from antibiotics and antihistamines to dental treatment and scans, and says clinical decisions remain with your own healthcare professional.

For complex cases, or when a professional is considering advising against breastfeeding, the Specialist Pharmacy Service directs clinicians to UKDILAS. You can ask your GP or pharmacist to seek that advice for you, and you can report a suspected side effect in the baby or yourself through the MHRA Yellow Card scheme.