Breastfeeding is contraindicated in infants with classic galactosemia (galactose 1 - phosphate uridyltransferase deficiency) 103; mothers who have
active untreated tuberculosis disease or are
human T - cell lymphotropic virus type I — or II — positive104, 105; mothers who are receiving diagnostic or therapeutic radioactive isotopes or have had exposure to radioactive materials (for
as long
as there is radioactivity in the milk) 106 — 108; mothers who are receiving antimetabolites or chemotherapeutic
agents or a small number of other medications until they clear the milk109, 110; mothers who are using drugs of abuse («street drugs»); and mothers who have herpes simplex lesions on a breast (infant may feed from other breast if clear of lesions).