Paul Niehans (21 November 1882 – 1 September 1971) was a Swiss surgeon. He is best known for developing fresh cell therapy, a form of alternative medicine. Due to unproven rumors that he had treated famous celebrities and world leaders, his clinic speciliazing in fresh cell therapy became popular.^[1][2] In 1955, he was appointed to the Pontifical Academy of Sciences after providing services to Pope Pius XII.^[2] There is no medical evidence to suggest his fresh cell therapy is useful for any health problem,^[3][4][5] and it has not been approved in several countries for safety reasons.

Fresh cell therapy is an alternative medicine where animal cells, dried or fresh, are injected into the muscles of humans.^[7] Niehans promoted it as a cure for many diseases and ailments, such as cancer, homosexuality, anemia, diabetes, heart issues, impotence, and sexual disfunction. He also advocated it as a form of breast enhancement.^[1]

There is no evidence it is useful for any health problem.^[3] Fresh cell therapy is considered an unproven method of cancer treatment and quackery by medical experts.^[4][5] In an 1963 investigation by the American Cancer Society, they found "no evidence that treatment with the Fresh Cell Therapy or "CT" results in any objective benefit in the treatment".^[4] There have been several instances of severe adverse effects including death.^[8]

In the United States and Switzerland, it is not legally available because of safety concerns and lack of proof of its effectiveness.^[9][7] The World Health Organization does not recognize its usefulness as a form of medical treatment.^[9]