People who use PCP may become highly agitated or violent. Those who use it regularly often harm others who are around them. They may also be violent against themselves. Other effects of PCP use include hallucinations, disorientation, paranoia, exaggerated feelings of self-importance, suicidal thoughts, memory loss, nausea or vomiting, a heightened awareness of sound, and the inability to speak. Heart or lung failure can also occur in some cases. The effects of the drug last for as long as it is in the body's system and as long as people continue to use the drug. Symptoms may last as long as a year after quitting use.

Addiction to PCP is both physical and psychological, in that it physically affects the body and the user feels that he or she cannot function without using the drug. Many people become addicted to the feelings of being invincible and other pleasurable feelings they get from the drug.

Treatment requires abstaining from using PCP. However, overdosing can occur quite easily, which means that some users are treated in a hospital setting. Psychological side effects can also lead a person to the emergency room. In these situations, the stomach is pumped to remove the drugs. Withdrawal symptoms can include convulsions, and both physical and chemical restraints may be applied. From there, complete abstinence is required and is a lifelong process.