Lawyers acting for 200 former patients, who have suffered recurring "flashbacks" as a result of being given the drug, will shortly issue writs against a number of hospitals.
The legal action, which is likely to seek damages and compensation running into tens of thousands of pounds, will expose the use of LSD to treat patients for more than 20 years from the 1950s.
Those given the drug - in doses above the amount taken in recreational use - ranged from people with mental illness to alcoholics and those suffering from post-natal depression. They were not told they were being given LSD and nor were they informed of its likely side effects.
These include flashbacks where people re-live their first "trip", sometimes as often as five times a week. One person has claimed the drug brought on epilepsy.
Solicitors Alexander Harris, who are representing the legally-aided patients, are planning to bring a number of test cases against selected hospitals and health authorities. Senior partner Ann Alexander said that despite the difficulty of individual cases dating back 30 years, they were confident the case would go ahead.
"We anticipate issuing proceedings in the very near future," she said.
The cases became known after patients at Powick Mental Hospital, then part of West Midlands Health Authority, complained to their MP, Ken Purchase. It then emerged that the problem was nation wide. Powick hospital has since closed.
A spokesman for the Labour MP said: "Ken is pleased we've got this far - and will be even more pleased if the actions are successful."Reuse content