Dexter Loos completed his medical studies at Auckland University graduating in 1981. 

He has been working as a GP at the Mount Wellington Medical Clinic since 1985.

As well as providing comprehensive family medicine, he has a special interest in the diagnosis and treatment of skin lesions including skin cancers. He also has extensive experience in performing vasectomy operations. He is an affiliated provider to Southern Cross Healthcare for both skin surgery and vasectomies.