UKDILAS: General Principles for Medicine Use during Breastfeeding

Laura Kearney, Regional Principal Medicines Information Pharmacist, Midlands and East Medicines Advice Service (East Midlands site) & UK Drugs in Lactation Advisory ServicePublished

A robust assessment of the balance of benefit to risk requires data both on the drug’s passage into breast milk and its effects in infants. The following principles should be followed when prescribing for breastfeeding mothers :

  • Avoid unnecessary drug use and limit use of over-the-counter (OTC) products
  • Breastfeeding mothers should seek advice on the suitability of OTC products
  • Assess the benefit/risk ratio for both mother and infant
  • Avoid use of drugs known to cause serious toxicity in adults or children
  • Drugs licensed for use in infants do not generally pose a hazard
  • Neonates (and particularly premature infants) are at greater risk from exposure to drugs via breast milk, because of immature excretory functions and the consequent risk of drug accumulation
  • Choose a regimen and route of administration which presents the minimum amount of drug to the infant
  • Drugs with a long half-life can increase the risk of accumulation in the infant , and increase the risk of adverse effects
  • Multiple drug regimens may pose an increased risk especially when adverse effects such as drowsiness are additive
  • Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms
  • Avoid new drugs if a therapeutically equivalent alternative that has been more widely used is available.


There is rarely enough information available for new drugs to allow robust risk assessment to be made. If a drug with limited data is deemed to be clinically necessary or for any further information, contact the UK Drugs in Lactation Advisory Service (UKDILAS) for further advice.

Search individual drugs on the SPS website for an assessment of suitability for use during breastfeeding.