Health effects

Short-term effects

LSD produces many physical and psychological short- and long-term effects which are unpredictable and can vary between people and from occasion to occasion.

Short-term effects include:

  • blurred vision
  • dilated pupils
  • increased blood pressure
  • rapid heart beat
  • irregular breathing
  • euphoria
  • a sense of relaxation and wellbeing
  • hallucinations, distorted sensory, emotional, space and time perception
  • distorted thinking, confusion, trouble concentrating and maintaining attention
  • anxiety, paranoia, feelings of panic
  • nausea, vomiting and loss of appetite
  • dizziness
  • poor coordination
  • increased body temperature leading to chills, hot and cold flushes
  • numbness.

Bad trip and come down

A ‘bad trip’ is when the effects of LSD are particularly intense or unexpected, or simply experienced as negative by the user.

A bad trip can be very unpleasant and include hallucinations of spiders crawling on the skin, losing control of emotions and feelings of ’going crazy’. Panic can lead to risky behaviour such as running across a busy street or jumping from heights.

Usually the negative effects wear off. However it has been known for users to experience hallucinations, bizarre behaviours and paranoia for several days after using the drug. Occasionally these effects can last weeks or months. 

Long-term effects

Flashbacks are the most common long-term effect of LSD use, and can occur days, weeks or even years after using the drug. Some people re-experience the effects. Flash backs can be sparked off by the use of other drugs, stress, fatigue, or physical exercise. They are usually visual and can last a minute or two.

There is some evidence that heavy use of LSD can impair memory and concentration. Using LSD may increase the risk of certain people developing severe mental disturbances.

Some people might experience ’drug-induced psychosis’ after using LSD. This is when the effects of the drug become prolonged and unwanted, involving hallucinations, delusions and bizarre behaviour. These episodes can last several hours, and for some people even longer.