The Health Effects of Marijuana
Negative Health Effects Are Numerous
By Buddy T, About.com
Updated: September 18, 2006
About.com Health's Disease and Condition content is reviewed by Steven Gans, MD
Although legalization activists and many marijuana users believe smoking pot has no negative effects, scientific research indicates that marijuana use can cause many different health problems.
Marijuana is the most commonly used illicit drug in the United States. When smoked, it begins to effect users almost immediately and can last for one to three hours. When it is eaten in food, such as baked in brownies and cookies, the effects take longer to begin, but usually last longer.
The short-term effects of marijuana include:
- Distorted perception (sights, sounds, time, touch)
- Problems with memory and learning
- Loss of coordination
- Trouble with thinking and problem-solving
- Increased heart rate, reduced blood pressure
Sometimes marijuana use can also produce anxiety, fear, distrust, or panic.
Effects on the Brain
The active ingredient in marijuana, delta-9 tetrahydrocannabinol or THC, acts on cannabinoid receptors on nerve cells and influences the activity of those cells. Some brain areas have many cannabinoid receptors, but other areas of the brain have few or none at all. Many cannabinoid receptors are found in the parts of the brain that influence pleasure, memory, thought, concentration, sensory and time perception, and coordinated movement.
When high doses of marijuana are used, usually when eaten in food rather than smoked, users can experience the following symptoms:
- Impaired memory
Effects on the Heart
Within a few minutes after smoking marijuana, the heart begins beating more rapidly and the blood pressure drops. Marijuana can cause the heart beat to increase by 20 to 50 beats per minute, and can increase even more if other drugs are used at the same time.
Because of the lower blood pressure and higher heart rate, researchers found that users' risk for a heart attack is four times higher within the first hour after smoking marijuana.
Effects on the Lungs
Smoking marijuana, even infrequently, can cause burning and stinging of the mouth and throat, and cause heavy coughing. Scientists have found that regular marijuana smokers can experience the same respiratory problems as tobacco smokers do, including:
- Daily cough and phlegm production
- More frequent acute chest illnesses
- Increased risk of lung infections
- Obstructed airways
Marijuana contains more carcinogenic hydrocarbons than tobacco smoke and because marijuana smokers usually inhale deeper and hold the smoke in their lungs longer than tobacco smokers, their lungs are exposed to those carcinogenic properties longer.
One study found that marijuana smokers were three times more likely to develop cancer of the head or neck than non-smokers. Many researchers believe than smoking marijuana is overall more harmful to the lungs than smoking tobacco.
Other Health Effects
Research indicates that THC impairs the body's immune system from fighting disease, which can cause a wide variety of health problems. One study found that marijuana actually inhibited the disease-preventing actions of key immune cells. Another study found that THC increased the risk of developing bacterial infections and tumors.
Effects of Exposure During Pregnancy
Several studies have found that children born to mothers who used marijuana during pregnancy exhibit some problems with neurological development. According to those studies, prenatal marijuana exposure can cause:
- Altered responses to visual stimuli
- Increased tremulousness
- Problems with sustained attention and memory
- Poor problem-solving skills
Link - http://alcoholism.about.com/od/pot/a/effects.htm