[2] Mepacrine is not the drug of choice because side effects are common, including toxic psychosis, and may cause permanent damage.

In addition to medical applications, mepacrine is an effective in vitro research tool for the epifluorescent visualization of cells, especially platelets.

It was used extensively during the second World War by Allied forces fighting in North Africa and the Far East to prevent malaria.

[11][12] Possible reasons for the lack of an in vivo effect include inefficient penetration of the blood–brain barrier, as well as the existence of drug-resistant prion proteins that increase in number when selected for by treatment with mepacrine.

[14] However, despite a multitude of clinical studies on the use of mepacrine and female sterilization, no randomized, controlled trials have been reported to date and there is some controversy over its use.

The FDA has waived the necessity for Phase II clinical trials because of the extensive data pertaining to other uses of mepacrine.

The next step in the FDA approval process in the United States is a Phase III large multi-center clinical trial.

[16][17] Nevertheless, in 1998 the Supreme Court of India banned the import or use of the drug, allegedly based on reports that it could cause cancer or ectopic pregnancies.