According to the American Academy of Pediatrics, breastfeeding is contraindicated in the following circumstances:

• your infant is diagnosed with a disease called galactosemia
• you are receiving radioactive treatment or are exposed to radioactive chemicals
• you are receiving chemotherapy
• you use drugs of abuse such as heroine, cocaine, or barbituates
• you have an active herpes lesion on the breast
• you are infected with human immunodeficiency virus (HIV)
• you have active tuberculosis