There are many biological side effects of stimulants partly related to their chemical structure:
- Amphetamines cause an increase of mental alertness, blood pressure, heart rate, blood glucose, free fatty acid levels, and muscle tension. They can trigger cardiovascular diseases (hypertension and stroke), glucose intolerance or death. General side effects include headache, irritability, anxiety, depression, aggression, convulsions, insomnia, nausea, dizziness and confusion. Prolonged intake of high doses of amphetamines can produce weight loss, paranoia, psychosis, compulsive behaviour and nerve damage. Continual use can lead to physiological and psychic dependency.
- Cocaine increases mental alertness, heart rate and blood pressure associated with constricted blood vessels. When consumed in one of purified forms it can lead to death. Deaths are generally attributed to myocardial infarction, coronary vasospasm and increased myocardial oxygen demand. Short-term effects of cocaine include mental alertness, euphoria, paranoia, irritability and anxiety. Prolonged application of cocaine causes addiction, mood disturbances, restlessness, hallucinations, irrational and violent behaviors.
- Methylphenidate (Ritalin) brings adverse side effects in form of headache, anxiety, delusions, hallucinations, excessive repetition of movements and paranoia.
- Nicotine increases heart rate, blood pressure, autonomic reactivity, vasoconstriction, blood lipid levels, plasma glucose, glucagon, insulin, and cortisol. Among over 4 000 different compounds in the tobacco smoke the carbon monoxide and carcinogens are the most dangerous. Since affinity of carbon monoxide to hemoglobin is about 230 times greater than for oxygen the exercise performance is badly affected by lowering maximum aerobic capacity and perturbed peripheral circulation. Nicotine produces alertness, euphoria, feelings of pleasure and is highly addictive.
- Caffeine increases heart rate, stroke volume, blood pressure, contractility of skeletal muscles, mobilization and use of free fatty acid by the muscles, metabolic rate and oxygen consumption. Caffeine also causes nervousness, insomnia, tremors, body dehydration, tolerance and withdrawal symptoms.