Medical Use of Marijuana Are there medical benefits of using marijuana that outweigh the negative effects? Also, the effects of marijuana can be very hazardous on the body.These are horrible side effects which accompany these illnesses. Smoking marijuana effects the short-term memory which makes most people grades fall. After smoking marijuana for a long period of time a person looses the ability to concentrate, and a person cant concentrate after there short-term memory is lost (Edwards 1). Even though there are dangerous effects that can result from the use of marijuana, it.