Users experience everything in a new way. All five senses are enhanced tremendously. Users may 'see' music and 'hear' colors. Users report time playing tricks on them. A moment can seem like ages and 4 hours can seem like only 10 minutes.
Some users experience intense feelings of insight with mystical or religious significance.
LSD blocks the serotonin 1 receptors while stimulating the serotonin 2 receptors. So far, every drug that stimulates the serotonin 2 receptors cause hallucinations. The greatest danger of LSD is bad trips which can physical or psychological in nature and leave lasting impressions on the psyche. Finally, as with any street drug, unknown contaminants can be present, so make sure you know what you're getting. LSD does not generally cause dangerous physical reactions, and blood pressure, body temperature, and other vital signs remain reasonably stable unless there are acute anxiety reactions.