A new article published in The Journal of Obstetrics and Gynaecology Research discussed that although most medications can be taken safely during breastfeeding, potential risks of infant toxicity do exist because all medications are excreted into breast milk to a certain extent. The amount of medication excreted in the breast milk depends mainly on drug variations, such as dosing and chemical characteristics of the formulation, and host factors like maternal pharmacokinetics (PK), variations of pregnancy-associated changes, and post-partum recovery. Neonatal drug exposure is generally assessed by calculating the expected total infant daily dose through breast milk and comparing it to the normal therapeutic dose. But, clinical PK studies are challenging to conduct in this population. The article reported that recently, research methods using population PK analyses and physiologically-based PK modeling and simulation techniques have been recognized as a complementary approach to the conventional PK studies in this field. It was stated that these efforts are important for rational risk assessment. Health benefits of lactation for both mother and child are significant and hence, breastfeeding should be encouraged. Lactating mothers who require to be under certain medications must seek additional advice from pharmacists or clinical pharmacologist with expertise in this area.