He was famous for his Harveian Oration at the Royal College of Physicians in 1970, on the motion of blood in the veins.

After a coronary thrombosis in the following year, Cohen decided to devote his life to the greater work of teaching.

[3] Cohen was appointed to the chair of medicine at Liverpool in 1934, a part-time position, enabling him to follow up the results of his teaching by keeping in contact with local colleagues and practitioners.

He was invested as an associate Knight of the Order of St John in 1961, the same year he was elected president of the General Medical Council.

He won the Gold Medal of the BMA in 1967 in recognition of his outstanding services to the Association and to the medical profession.

Lord Cohen Medal, named after him, is awarded to individuals who "have made a considerable contribution to ageing research, either through original discoveries or in the promotion of the subject of gerontology in its broadest aspect."