Marijuana is made from the cannabis plant and contains THC, which causes the "high" feeling. It is usually smoked like cigarettes or in pipes. Marijuana affects areas of the brain associated with pleasure, memory, and time perception. Short term effects include euphoria, increased appetite, rapid heart rate, and red eyes. Withdrawal symptoms can include insomnia, hyperactivity, and decreased appetite. Long term risks include paranoia, fatigue, immune system issues, and behavioral effects on children exposed prenatally. However, marijuana also has some potential medical benefits such as helping with nausea, spasms, and AIDS symptoms.