Breastfeeding is contraindicated only for infants affected by rare diseases such as galactosemia, maple syrup urine disease and phenylketonuria (some breastfeeding is possible, under careful monitoring, in the latter condition, UNICEF/WHO, 2006a). These infants need special formulae, not the ordinary ones available to the general public.

There are other circumstances where infants may need formula as a replacement or supplement to breast milk for a limited period of time (UNICEF/WHO, 2006a). Examples are:

• infants born less than 1500 g or less than 32 weeks gestational age;
• newborns who have experienced severe stress during delivery;
• infants who are ill or whose mothers are diabetic;
• infants younger than 6 months with severe growth faltering not caused by illness and not reverted by frequent, effective suckling.

A breast abscess does not contraindicate breastfeeding; infants can be fed on the unaffected breast and breastfeeding from the affected breast can resume once the abscess has been drained and antibiotic treatment has started (WHO, 2000e). Women with herpes lesions of the breasts should also avoid breastfeeding until all active lesions have resolved (Henrot, 2002). In the case of maternal tuberculosis and Lyme disease, breastfeeding is safe once the mother has started treatment (WHO, 1998a; Shapiro, 1995). With few exceptions (radioactive iodine, sedating psychotherapeutic drugs, antiepileptics and opioids, cytotoxic drugs used for chemotherapy of cancer) maternal medications do not impede breastfeeding (WHO, 2003b). Even when a mother is drug dependent or an injecting drug user, breastfeeding may not be contraindicated depending on which drug is used (NSW Health, 2006).

The most appropriate option for HIV infected mothers (and for the less frequent cases of infection with human T-cell leukaemia virus) depends on individual circumstances (WHO, 2006g). When formula feeding is acceptable, feasible, affordable, sustainable and safe, which is usually the case in EU countries, avoidance of breastfeeding is recommended. When this is not the case, the availability of health services and of competent counselling and support should be taken into consideration before advising the mother to formula feed.

Also see EUphacts HIV/AIDS and Drug use.