Defining the risks of medicines in breastfeeding

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This article describes the features that support the risk classifications we assign to the use of medicines in breastfeeding

Risk classification

The compatibility of medicines with breastfeeding has been assessed through a combination of risk to the breastfed infant and the quality and/or volume of evidence available.

Medicines have been assigned to one of the following categories.


This risk classifications means that:

  • serious adverse effects have been reported, or are considered possible, in a breastfed infant
  • breastfeeding could be compromised because of an impact on milk production


This risk classifications means that:

  • minor and/or reversible adverse effects have been reported, or are considered possible, in breastfed infants, but which are not considered to pose an unacceptable risk to the infant
  • insufficient evidence of the amount of medicine excreted into breast milk
  • insufficient evidence, or experience of use in practice, to guarantee safe use with breastfeeding
  • use of a medicine is conditional on risk-reducing actions being taken, e.g. monitoring the infant or using a lower-risk formulation.


This risk classifications means that:

  • levels in milk are sufficiently low, or predicted to be low because of the medicine’s properties, that they would not present an appreciable risk to the infant
  • substantial clinical experience of the medicine has not indicated any risks
  • the medicine is in clinical use in young infants at doses significantly exceeding those which would be ingested through breast milk

Seek advice

Further advice should be sought if the use of the medicine requires an assessment of potentially complex issues, including an assessment of risk and safety in individual cases.

For example, the medicine may normally be used in combination with other medicines which may present additional risks to those posed by the initial medicine alone. This would apply to the treatment of HIV infection or cancer in breastfeeding mothers, although other therapy areas may also fit these criteria.


Update history

  1. Editorial and formatting amendments only
  1. Published

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