LSD long term use and effects can be very serious. Long term effects of LSD use can occur in anyone who uses LSD, though heavy users, or those who use the drug over a longer period of time, are more likely to experience long term effects.LSD long term use and effects include:1  Tolerance, which causes a person to take more of the drug, which can lead to life-threatening overdoses. 2  Acid flashbacks, or hallucinogen persisting perception disorder, an uncontrolled event where the person experiences the effects of LSD use again without taking the drug.SD long term use and effects can be very serious. Long term effects of LSD use can occur in anyone who uses LSD, though heavy users, or those who use the drug over a longer period of time, are more likely to experience long term effects. LSD long term use and effects include: