Short-term physical effects from marijuana use may include sedation, bloodshot eyes, increased heart rate, coughing from lung irritation, increased appetite, and decreased blood pressure. Many marijuana smokers experience serious health problems such as bronchitis, emphysema, and bronchial asthma. Withdrawal from chronic use of high doses of marijuana causes physical signs including headache, shakiness, sweating, stomach pains, nausea, restlessness, irritability, sleep difficulties, and decreased appetite. No deaths from overdose of marijuana have been reported.
When marijuana is smoked, the THC passes from the lungs into the bloodstream, eventually reaching the brain. In the brain, the THC connects to receptors which influence pleasure, memory, thought, concentration, sensory and time perception, and coordinated movement. Short-term effects of marijuana include problems with memory and learning, distorted perception, difficulty in thinking and problem-solving, and loss of coordination
The effect marijuana has on perception and coordination is responsible for serious impairments in learning, associative processes, and psychomotor behavior (driving abilities). Long term, regular use can lead to physical dependence and withdrawal following discontinuation, as well as psychic addiction or dependence. Clinical studies show that the physiological, psychological, and behavioral effects of marijuana vary among individuals. They include: