Subacute myelo-optic neuropathy (SMON) is an iatrogenic disease of the nervous system leading to a disabling paralysis, blindness and even death. Its defining manifestation was as an epidemic in Japan during the 1960s, affecting an estimated 30,000 people. On August 3, 1978, the Tokyo District Court ruled that the cause of SMON is Clioquinol. Its manufacturer, Ciba-Geigy, has publicly stated that "Medical products manufactured and sold by us have been responsible for the occurrence of [SMON] in Japan, we extend our apologies."
SMON was first observed and diagnosed in Sweden 1966, by the pediatrician and neurologist Olle Hansson. Clioquinol was marketed as a prophylaxis to tourist diarrhoea. Dr. Olle Hansson was in the front line, fighting for a ban of clioquinol. Doctors in many countries boycotted Ciba-Geigy for many years. Not until 1985 was the pharmaceutical withdrawn. Dr Hansson died a few months later. The day of his death, May 23, is observed as the Anti-Hazardous Drug Day in several parts of the world.