Irena Hanna Wittek (1917-2005) was born in Vienna. She and her two brothers, Roman and Eugeniusz, grew up in Lwów, Poland (now L'viv, Ukraine). Their parents were Maurycy and Helena Roth. Maurycy was a lawyer from a modest family background in Eastern Galicia. The Reitmann family hired him as a tutor for their daughter Helena, who he married. Helena's family was part of the Jewish elite of Lwów.  Her father, Solomon Reitmann, was the director of a brewery (which exists to his day under the name L'vivs'kyi Pyvovarnyi Zavod) . Helena's brother, Jerzy Reitmann, was an art collector and owned a retreat for writers and artists in the Carpathians.

Irena's parents sent her to study medicine in Paris in order to get her away from both a Communist boyfriend and the anti-Semitic atmosphere at Polish universities in the late 1930s. In the summer of 1940, as the Germans invaded, she made her way to England on one of the last boats with her then partner, Leopold Weissman, who returned to Poland after the war. 

Irena's father was shot in 1941. Her mother jumped to her death from the train taking her to Belzec extermination camp. Her brothers also perished in Poland.

Irena Wittek continued her studies at the Polish School of Medicine at the University of Edinburgh between 1943 and 1948. She married Antoni Wittek, a medical professional, in 1949. In 1949-1952, they both worked for the public health service in Kitwe, Northern Rhodesia. After her return to the UK, Irena Wittek specialised in paediatrics and children with special needs. Antoni Wittek continued his work in Northern Rhodesia until 1961. From 1964 until her retirement in 1983, Irena worked as senior medical officer in child health at St Christopher's Health Clinic, Battersea.

Irena Wittek became friends with Polish (later British) artist, film-maker and stage designer Franciszka Themerson and was part of a circle of Polish Jewish writers who frequented the Themerson house.