However, they were able to treat some problems fairly effectively, though for many ailments, treatment consisted mainly of guesswork, and some treatments were actually harmful. Plato was against the use of medicines for anything but the most desperate circumstances. He believed that the use of medicines on minor diseases could lead to more serious problems over time. It seems he was speaking of the sometimes-dangerous side effects that drugs can produce. Considering what we know today about how a seemingly harmless allergy medicine can lead to a fatal heart disease this was a very astute observation of the time.
Epilepsy is probably the most written about disease in Ancient Greece.
It was a scary disease due to its violent onset and symptoms. It was often attributed to demonic possession or a divine curse. It wasn't until Hippocrates that it was finally defined as a disease of the brain. He suggested that the cause is an excess of phlegm that would cut off the airflow to the brain and hence intelligence or consciousness since air was thought to be the source of intelligence. When the stoppage resolved itself, air and intelligence would return.