Paclitaxel is a taxane with antimitotic properties originally derived from the bark of the Pacific yew (Taxus brevifolia).Indicated for the treatment of various cancers (breast, ovarian, lung, pancreatic).Administered intravenously; a dose generally every 3 weeks during a number of rounds determined according to protocol. Some types of cancer require weekly doses (EMA 2016, AEMPS 2012). Because it is very lipophilic, it is excreted in breast milk in significant amounts. At 316 hours (13 days) after the infusion, detectable levels were no longer found in breast milk (Griffin 2012). There are two different pharmaceutical forms of paclitaxel, the conventional one (AEMPS 2012, Bristol 2011) and the albumin-bound nanoparticle (EMA 2016), with a very similar pharmacokinetic profile: high protein binding, high volume of distribution and a long half-life of around a day, the range being between 13 and 53 hours for the broadest conventional form (Bristol 2011), versus 12 to 33 hours for the nanoparticle form (EMA 2016). When it is possible to do so, detections in the milk of each patient to determine the total elimination of the drug would be the best indicator for resuming breastfeeding between two rounds of chemotherapy. It is known from pharmacokinetics that after 3 elimination half-lives (T½) 87.5% of the drug is eliminated from the body; after 4 T½ 94%, after 5 T½ 96.9%, after 6 T½ 98.4% and after 7 T½ 99%. From 7 T½ plasmatic concentrations of drug in the body are negligible. In general, a period of five half-lives can be considered a safe waiting period before a return to breastfeeding (Anderson 2016). Depending on the pharmaceutical form of paclitaxel and taking as reference the longest recorded T½, these 5 T½ would correspond to the conventional form of paclitaxel at 11 days and that of nanoparticles at 7 days. Expert authors recommend waiting 6 to 10 days (between 6 and 10 T½) after the last dose to restart breastfeeding. Meanwhile, express and discard breast milk regularly (Hale 2017 p.742). Some chemotherapeutic agents with an antibiotic effect can alter the composition of the microbiota (cluster of bacteria or bacterial flora) of the milk and the concentration of some of its components (Urbaniak 2014). This possibly occurs temporarily with subsequent recovery, without any adverse effects being reported in breastfed infants.