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 blood contaminated needles 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.
Stimulants can cause increased heart and respiratory rates, elevated blood pressure, dilated pupils, and decreased appetite. In addition, users may experience sweating, headaches, 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 reported 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.