The effects of LSD will differ from user to user.  Ones experience will be influenced by what state of mind they are in, how much acid they have taken and their surroundings.  Because of this, a high from a hit of LSD can be quite unpredictable.  However, many people will begin to hallucinate, their perceptions will be altered, they may see and hear things differently then normal, images may be sharper and colors brighter.

Individuals may also begin to sweat and not feel like eating.  Their moods may swing, being happy one minute and then sad the next. It is also possible to become delusional and paranoid.  Users may feel like others are out to get them.

LSD can also cause panic attacks and individuals can become extremely frightened.  Persons that use LSD for long periods of time may suffer from flash backs of prior LSD use.  They may also become paranoid and stop practicing good hygiene or taking good care of themselves.  They may become increasingly isolated from others and constantly think about getting high and using LSD.  Individuals that have a history of mental illness may find that those conditions are exasperated with both long-term and short-term LSD use.