Prohibited drugs during breastfeeding are usually drugs that are prohibited to be taken during breastfeeding, such as aspirin and some antibiotics. If a prohibited drug is taken once during breastfeeding, it may affect the growth and development of the baby if the prohibited drug can be secreted through breast milk. If a woman takes a drug during breastfeeding, the drug may be secreted through breast milk. The milk containing the drug is drunk into the body by the baby and enters the blood circulation which may affect the growth and development of the baby, and may even affect the development of the baby’s key parts such as the brain. Therefore, women should be careful in using drugs during breastfeeding. If a woman takes a small amount of a prohibited drug, or if the prohibited drug is not metabolized by breast milk, the effect on the baby may be less. When a woman takes a banned substance during breastfeeding, she should drink plenty of water to promote the excretion of the drug, suspend breastfeeding until the drug is metabolized, and go to the hospital and consult a doctor if necessary.