Function

Psychedelic mushrooms contain the substances psilocybin and psilocin, which can alter your consciousness. These drugs are said to have an effect similar to a low dose of LSD, or acid.

Effects

Though each person who takes psychedelic mushrooms will have a different experience, some common effects they have include altering the mind and perceptions of sound and sight. Colors may become more vivid and sounds seem "brighter."

Short-Term Side Effects

Some of the undesirable side effects of psychedelic mushrooms may include nausea, sickness, stomach pain, vomiting and diarrhea. You may also experience feelings of paranoia or lack of control.

Long-Term Side Effects

Although not much research has been done on the long-term effects of psychedelic mushrooms, your body may build up a tolerance to the drug. Unlike "hard" drugs, though, psychedelic mushrooms do not appear to cause the same feelings of withdrawal.

Additional Effects

Psychedelic mushrooms and other psychedelic drugs have the power to magnify any emotions you are experiencing, so it is important not to take the drug if you are feeling depressed, sad, anxious or are feeling generally discontent with your life.

Source:

Guide4Living.com: The Effects of Magic Mushrooms

TheGoodDrugsGuide.com: Are mushrooms dangerous?