Cocaine stimulates the central nervous system. Its immediate effects include dilated pupils and elevated blood pressure, heart rate, respiratory rate, and body temperature. Occasional use can cause a stuffy or runny nose, while chronic use can ulcerate the mucous membrane of the nose. Injecting cocaine with unsterile equipment can cause AIDS, hepatitis, and other diseases. Preparation of freebase, which involves the use of volatile solvents, can result in death or injury from fire or explosion. Cocaine can produce psychological and physical dependency, a feeling that the user cannot function without the drug. In addition, tolerance develops rapidly.

Crack or freebase rock is extremely addictive, and its effects are felt within 10 seconds. The physical effects include dilated pupils, increased pulse rate, elevated blood pressure, insomnia, loss of appetite, tactile hallucinations, paranoia, and seizure.

The use of cocaine can cause death by disrupting the brain's control of the heart and respiration.

Stimulants can cause increased heart and respiratory rates, elevated blood pressure, dilated pupils and decreased appetite. In addition, users may experience sweating, headache, blurred vision, dizziness sleeplessness, and anxiety. Extremely high doses can cause a rapid or irregular heartbeat, tremors, loss of coordination, and even physical collapse. An amphetamine injection creates a sudden increase in blood pressure that can result in stroke, very high fever, or heart failure.

In addition to the physical effects, users report feeling restless, anxious, and moody. Higher doses intensify the effects. Persons who use large amounts of amphetamines over a long period of time can develop an amphetamine psychosis that includes hallucinations, delusions, and paranoia. These symptoms usually disappear when drug use ceases.

The effects of depressants are in many ways similar to the effects of alcohol. Small amounts can produce calmness and relaxed muscles, but somewhat larger doses can cause slurred speech, staggering gait, and altered perception. Very large doses can cause respiratory depression, coma, and death. The combination of depressants and alcohol can multiply the effects of the drugs, thereby multiplying the risks.

The use of depressants can cause both physical and psychological dependence. Regular use over time may result in a tolerance to the drug, leading the user to increase the quantity consumed. When regular users suddenly stop taking large doses, they may develop withdrawal symptoms ranging from restlessness, insomnia, and anxiety to convulsions and death.

Babies born to mothers who abuse depressants during pregnancy may be physically dependent on the drugs and show withdrawal symptoms shortly after they are born. Birth defects and behavioral problems also may result.

Phencyclidine (PCP) interrupts the functions of the neocortex, the section of the brain that controls the intellect and keeps instincts in check. Because the drug blocks pain receptors, violent PCP episodes may result in self-inflicted injuries.

The effects of PCP vary, but users frequently report a sense of distance and estrangement. Time and body movement are slowed down. Muscular coordination worsens and senses are dulled. Speech is blocked and incoherent.

Chronic users of PCP report persistent memory problems and speech difficulties. Some of these effects may last six (6) months to a year following prolonged daily use. Mood disorders - depression anxiety, and violent behavior - also occur. In later stages of chronic use, users often exhibit paranoid and violent behavior and experience hallucinations. Large doses may produce convulsions and coma, heart and lung failure, or ruptured blood vessels in the brain.

Lysergic acid (LSD), mescaline, and psilocybin cause illusions and hallucinations. The physical effects may include dilated pupils, elevated body temperature, increased heart rate and blood pressure, loss of appetite, sleeplessness, and tremors.

Sensations and feelings may change rapidly. It is common to have a bad psychological reaction to LSD, mescaline, and psilocybin. The user may experience panic, confusion, suspicion, anxiety, and loss of control. Delayed effects, or flashbacks, can occur even after use has ceased.

Narcotics initially produce a feeling of euphoria that often is followed by drowsiness, nausea, and vomiting. Users also may experience constricted pupils, watery eyes, and itching. An overdose may produce slow and shallow breathing, clammy skin, convulsions, coma, and possibly death.

Tolerance to narcotics develops rapidly and dependence is likely. The use of contaminated syringes may result in diseases such as AIDS, endocarditis, and hepatitis. Addiction in pregnant women can lead to premature, stillborn, or addicted infants who experience severe withdrawal symptoms.

Illegal drugs are defined in terms of their chemical formulas. To circumvent these legal restrictions, underground chemists modify the molecular structure of certain illegal drugs to produce analogs known as designer drugs. These drugs can be several hundred times stronger than the drugs they are designed to imitate.

The narcotics analogs can cause symptoms such as those seen in Parkinson's disease - uncontrollable tremors, drooling, impaired speech, paralysis, and irreversible brain damage. Analogs of amphetamines and methamphetamines cause nausea, blurred vision, chills or sweating, and faintness. Psychological effects include anxiety, depression, and paranoia. As little as one dose can cause brain damage. The analogs of phencyclidine cause illusions, hallucinations, and impaired perception.