Marijuana has numerous effects on the user. It's effects are produced by a chemical called THC (delta-9-tetrahydrocannabinol). This chemical in marijuana is what creates the users "high". THC is found in the marijuana plant and has a higher potency level when it is located in the flowers or buds of the plant. The effects of the THC in the marijuana plant when it is smoked quickly travel through the blood into the lungs and then to the brain. When the THC reaches the brain it creates marijuana's effect of being "high".

Intensity of the effects of marijuana differ person to person. The variables include: how much taken, how strong (potent) the marijuana is, how the marijuana is taken (joint, bong, food), size, weight, health, mood, individual experience with marijuana, if marijuana is taken with other drugs, and whether alone or with other people, at home or at a party.

Here is a typical breakdown of the timeframe of marijuana effects:
Onset 0-10 minutes
Coming Up 5-10 minutes
Plateau 15-30 minutes
Coming Down 45-60 minutes
After Effects 30-60 minutes

• Sleepiness
  
• Difficulty keeping track of time, impaired or reduced short-term memory
  
• Reduced ability to perform tasks requiring concentration and coordination, such as driving a car
  
• Increased heart rate
  
• Potential cardiac dangers for those with preexisting heart disease
  
• Bloodshot eyes
  
• Dry mouth and throat
  
• Decreased social inhibitions
  
• Paranoia, hallucinations
  
• Impaired or reduced short-term memory
  
• Impaired or reduced comprehension
  
• Altered motivation and cognition, making the acquisition of new information difficult
  
• Paranoia
  
• Psychological dependence
  
• Impairments in learning, memory, perception, and judgment - difficulty speaking, listening effectively, thinking, retaining knowledge, problem solving, and forming concepts
  
• Intense anxiety or panic attacks