Because marijuana contains irritants and carcinogens, it promotes cancer of the lungs and other parts of the respiratory tract. Marijuana also produces high levels of an enzyme that converts some hydrocarbons into their carcinogenic form. These levels may accelerate the changes that ultimately produce malignant cells. Additionally, marijuana users typically inhale more deeply and hold their breath longer than tobacco smokers, increasing the lungs exposure to carcinogenic smoke.

Users who smoke marijuana regularly may experience the same respiratory problems as tobacco smokers, including daily cough and phlegm, symptoms of chronic bronchitis, and frequent chest colds. Continued marijuana use can result in abnormal functioning of lung tissue injured or destroyed by marijuana smoke.

Within a few minutes after smoking marijuana, the user's heart begins to beat more rapidly and may increase by 20 to 50 beats per minute or double. Results of a study released in 2001 indicate that a person's risk of heart attack within the 1st hour of smoking marijuana is four times the usual risk.

Marijuana use is associated with numerous detrimental health effects, including frequent respiratory infections, increased heart rate, impaired memory and learning, anxiety, and panic attacks.

Effects on the Brain

Marijuana's effects begin as soon as the drug enters the brain and can last from 1 to 3 hours. As THC enters the brain, it causes the user to feel high by stimulating brain cells to release the chemical dopamine. When the euphoria passes, the user may feel sleepy or depressed and may also get feelings of panic, anxiety, paranoia or distrust.

Marijuana can cause short-term memory damage because of how THC alters the way information is processed by the hippocampus. THC disrupts coordination and balance by binding to parts of the brain that regulates balance, coordination of movement, posture, and reaction time.

Street terms for marijuana: grass, pot, weed, bud, Mary Jane, dope, indo, hydro.

Marijuana is a mixture of the dried, shredded leaves, seeds, stems, and flowers of the hemp plant, cannabis sativa. It is typically smoked in joints (hand-rolled cigarettes), blunts (cigars), pipes, or bongs (water pipes). The active ingredient in marijuana is THC, which is responsible for the potency and effects of marijuana. Over the past two decades, THC levels of marijuana in the United States have increased.

Commercial-grade marijuana contains parts of the marijuana plant such as stems and seeds that are not of high quality. "Sinsemilla", higher potency marijuana, contains only the leaves and buds of the cannabis plant, where THC is most concentrated.