It's universally well known that breastfeeding, due to its numerous beneficial effects on child and maternal health, is the best feeding method for infants. The use of medication by the nursing mother and the physician's advice to stop nursing are the most common reasons for the cessation of breastfeeding. The physician plays an extremely delicate role and should be able to assess risks and benefits for both mother and child. The issue of which drugs are safe to take during lactation is quite complicated. Three main factors must be taken into account: pharmacokinetics, assessment of the risk to the infant and to the lactation. Excellent sources of reliable information are the reference books. For the most up-to-date information it would be useful to consult the online medical literature. Few drugs have been demonstrated to be absolutely contraindicated during breastfeeding. Clear, safe and reliable information is still lacking for most drugs. It would be desirable to see an improvement in knowledge about mechanisms for transfer of drugs into milk, to analyze the biotransformation process for a given drug and to study the clinical consequences of infant exposure to drugs present in milk.