In 2010, at Erasmus Medical Center he was appointed Professor in Clinical Pharmacology. His research at the Erasmus Medical Center was focused on clinical pharmacology and therapeutic drug monitoring. He was the chairman of the Dutch Society for Clinical Pharmacology & Biopharmacy, the secretary of the Dutch Society for Transplantation, and the President of the International Association for Therapeutic Drug Monitoring and Clinical Toxicology.
In December 2019 Teun van Gelder accepted a new position in Leiden University Medical Center (LUMC). He was appointed Professor in Drug Discovery & Development. LUMC, Leiden Institute of Chemistry, Leiden Academic Centre for Drug Research (LACDR), Centre for Human Drug Research (CHDR), and Leiden Bio Science Park (LBSP) together have the expertise and facilities for the design, development, and testing of new innovative drugs. This environment is unique in the Netherlands and provides an excellent basis for drug discovery and drug development. In his role as an experienced internist – clinical pharmacologist Teun will make an important contribution to Academic Pharma.