It is hard to know how the hallucinogenic experience or 'tripping' will turn out. Immediate effects The effects of LSD usually begin within half an hour of taking the drug, are at their strongest in 3 to 5 hours, and last for up to 12 hours. While using LSD or 'tripping', the person may experience strong feelings of anxiety or fear. The hallucinatory effects can be unpleasant, such as spiders crawling on the skin. Or they can be so intense that the person feels as if they are losing control and 'going crazy'.
Panic can lead to risky behaviour, such as running across a busy street.
This can cause the person to accidentally injure him or her self, for example by diving into rough surf. When negative feelings dominate the experience it is described as a 'bad trip'. The reasons for bad trips are not known. They are particularly common among first-time users. When a 'bad trip' occurs, the user needs to be reassured and calmed until the immediate effects have passed, although this can take many hours.