Stimulants are are prescribed to people with depression and children with attention deficit. When you take stimulants, they increase alertness and energy levels in the brain and the rest of the body. An issue with stimulants is that they are very addicting so people tend to take to many. An overdose of stimulants could cause heart attacks, seizures, anger, nerve problems, and even stomach problems.
There are legal and illegal forms of depressants. Drinking alcohol is an example of a legal depressant. Opioids/Heroin are an example of illegal depressants. Depressants can also be prescribed to people who need induced sleep or to relieve stress. An overdoes of any depressant can cause problems with breathing, sleeping, depression, and even death.
Yes, there are legal forms of drugs such as stimulants and depressants that are also harmful to the mind and body, but they usually only are if they are being abused.
Last answer got deleted for being vague so I hope this is better