Lowenfeld followed her sister into the London Royal Free Hospital School of Medicine for Women in Bloomsbury, London. By the outbreak of the First World War, she had passed the minimum requirement to practice medicine, In 1914 she got a job at the Royal Free Hospital followed by a short period at the Hospital for Sick Children, Great Ormond Street. In 1917 she got the MRCS (Eng.) and LRCP (Lond.) and the MB, BS (Lond.). In 1918 she became a house surgeon at the South London Hospital for Women.