Mothers with asthma who are breastfeeding are often concerned that the medications used may have adverse effects on their infants when they enter the breast milk. In general, medications used in inhalation therapy have little effect on the baby because the amount entering the circulation is very small, and the mother can continue to breastfeed her child. Oral medications are a different story. Some oral medications can also increase in concentration in the breast milk at high doses and may have adverse effects on the baby. For example, when mothers use theophylline drugs, theophylline in breast milk accounts for 1/10 of their intake, and some infants may experience agitation, rapid heartbeat, and insomnia when the dose is too high. Some antihistamines are also present in breast milk at certain concentrations, and the infant may show drowsiness and occasional irritability and restlessness when the mother overdoses. In conclusion, oral medication should be avoided as much as possible for breastfeeding mothers with asthma, and inhalation therapy is the safest method of administration for both mother and baby.