There are very few infant populations who cannot tolerate breast milk:

  • Infants with galactosemia, a rare condition preventing digestion of the sugar galactose, cannot breastfeed.
  • Infants with phenylketonuria (PKU) cannot exclusively breastfeed.
  • Infants with certain other allergies, such as dairy or wheat, can still nurse if mothers exclude these foods from their diets (Debate exists about this topic, please see the following: ABM Clinical Protocol #24 and The Role of Maternal Dietary Restriction, Breastfeeding for more information. 

Mothers who should not breastfeed include those:

  • Diagnosed with HIV, AIDS, or taking antiretroviral medications (however, mothers in developing countries may be encouraged to breastfeed due to lack of resources and low risk of infection transmission).
  • Diagnosed with human T-cell lymphotropic viruses Type I or II.
  • With an active herpes simplex lesion on her nipple or areola; however nursing on the unaffected breast in this situation is acceptable. It should be recommended to “pump and dump” on the affected breast in order to maintain milk supply throughout the outbreak.
  • Taking anti-metabolite medications for chemotherapy.
  • Using or addicted to illicit drugs.
  • Radioactive compounds require temporary cessation of breastfeeding.


  • Smoking tobacco is not a contraindication to breastfeeding.
  • Mothers should be encouraged to cut down or quit smoking altogether during lactation to minimize infant exposure.
  • If a mother cannot quit entirely, smoking is not a contraindication to breastfeeding, and the baby will need the extra protection from breast milk to prevent respiratory infections and other problems.
  • Mothers should be counseled to smoke after nursing to minimize nicotine transfer in breast milk, and not to smoke near the baby.
  • Smoking can diminish milk supply, and cigarette smoke has also been related to SIDS.


According to The American College of Obstetricians and Gynecologists (ACOG) Marijuana Use During Pregnancy and Lactation Policy Statement and the AAP Clinical Report Marijuana Use During Pregnancy and Breastfeeding: Implications for Neonatal and Childhood Outcomes:

  • All women should be asked about their use of tobacco, alcohol, and other drugs, including marijuana and other medications used for nonmedical reasons.
  • Women reporting marijuana use should be counseled about concerns regarding potential adverse health consequences of continued use during pregnancy.
  • Women who are pregnant or contemplating pregnancy should be encouraged to discontinue marijuana use.
  • There are insufficient data to evaluate the effects of marijuana use on infants during lactation and breastfeeding, and in the absence of such data, marijuana use is discouraged.
  • Although marijuana is legal in some states, pregnant women who use marijuana can be subject to child welfare investigations if they have a positive marijuana screen result. Health care providers should emphasize that the purpose of screening is to allow treatment of the woman’s substance use, not to punish or prosecute her.
  • Pregnant or breastfeeding women should be cautioned about infant exposure to smoke from marijuana in the environment, given emerging data on the effects of passive marijuana smoke.

    The ACOG report can be found here and the AAP Clinical Report can be found here.

Breast Augmentation or Reduction:

  • A history of breast surgery is not a contraindication to breastfeeding.
  • Breast implants are rarely a problem in breastfeeding.
  • Breast reduction may lead to decreased milk production.
  • In either case, breastfeeding is still recommended, but growth of infant and milk supply should be closely monitored.