It's often stated that LSD causes hallucinations, but that's not quite true. When a person has a hallucination, he or she believes that everything that he or she sees and feels is real. LSD changes the way people perceive the world around them, as well as what they think and feel, but people on LSD don't see things that aren't there. They see what's already there in a different way, and most of the time, they're aware that their altered perceptions are caused by the drug.
After taking LSD, the effects -- known as a "trip" -- usually start within an hour and can last up to 12 hours, with a peak about halfway through the experience. Exactly how LSD affects each person varies widely. Some physical changes in the body during tripping include dilated pupils, increased blood pressure and a high body temperature. People on LSD may also feel dizzy, sweat, have blurred vision and feel tingling in their hands and feet. They may feel drowsy but not sleepy.
LSD's primary effects are visual. Colors seem stronger and lights seem brighter. Objects that are stable might appear to move or have a halo of light around them. Sometimes objects have trails of light coming from them or appear smaller or larger than they really are. LSD users often see patterns, shapes, colors and textures. Sometimes it seems that time is running backward, or moving very quickly or slowly. On very rare occasions (although it's sometimes portrayed as common), tripping can cause synesthesia -- a confusion of sensations between different types of stimuli. Some people have described this as seeing colors when they hear specific sounds.
There is an overall sense of happiness and euphoria. Everything is beautiful, interesting and magical. People on LSD often become very emotional and dreamlike. Large doses of may make them feel especially contemplative. They feel that their mind has burst through its normal boundaries, and they often claim to have had experiences that are spiritual or religious, with a new understanding of how the world works.
People tripping on LSD are generally impulsive and have very poor judgment. This is part of why it's usually preferable among LSD users to trip in groups, especially with others who have experience, and in calm places like home or in a park. Close friendships have been formed among people who have tripped together. For people not tripping but observing, LSD users can be scary. They might spend lots of time pondering something that appears incredibly unimportant. They aren't always easy to understand, but when they do talk, they speak quickly and jump from subject to subject.
The above are considered to be "good trips." Most people who have used LSD know that there's always a possibility of having a "bad trip." It's not really clear what causes a bad trip, especially since each trip can be very different depending on the person. LSD users sometimes say that it's due to the "set and setting." This means that if you are already in a bad mood, or you trip in a highly structured environment that requires you to think logically (such as school), you could have a bad trip. This may include losing sight of the illusory aspect of tripping, which results in fear and paranoia. The loss of control is frightening, and it seems like the trip will never end. Sometimes when someone has a bad trip, he or she is taken to a hospital. However, there usually isn't much that doctors do other than give the person a quiet space and reassurance. They may administer an anti-anxiety medication or a mild tranquilizer to ease the patient's panic. As the trip ends, the patient may feel dizzy or nauseous, but people usually recover with no lasting side effects.
For some, one bad trip is enough to swear off LSD forever. Even if LSD users don't have a bad trip, heavy use of LSD can still cause a lot of problems. Next, we'll look at how LSD works in the body and its effects on mental and physical health.