Dr. Nickelsen completed his undergraduate and medical school training at Northwestern University. He then went on to residency in Pediatrics at Children's Hospital in Buffalo, NY, followed by Allergy/Immunology fellowship at SUNY in Buffalo as well. He was an Assistant Professor of Pediatrics and Director of the Allergy/Immunology Division at East Carolina University from 1979 to 1983. He also served as the Chief of Allergy and Director of the Children's Hospital of Oakland from 1986 to 1998. Dr. Nickelsen has been in practice in Berkeley since 1984, and joined ranks with Allergy and Asthma Medical Group in 2005. He has been a physician volunteer with the American Lung Association Summer Asthma Camp. Dr. Nickelsen is a fellow of the American Academy of Allergy, Asthma and Immunology and a member of the Western Society of Asthma, Allergy and Immunology.