Although most people agree that marijuana is not addictive, it can be habit-forming, and many mariuana users use the drug habitually and do experience negative effects when stopping usage. Because the active ingredient in marijuana, THC, builds up in the body and creates a tolerance, habitual users have to smoke a larger amount to achieve the same effects. The negative impact of this need to smoke a larger amount is that the cost may become greater. The user may also spend a longer period of time engaging with and under the influence of the drug, since it takes a longer time to smoke enough to achieve the same "high." Because the drug is illegal, there is also the risk of criminal prosecution. Some habitual users report experiencing negative cognitive effects such as becoming more forgetful or more easily distracted, or less disciplined and energetic, but these effects are largely anecdotal and have not been scientifically documented. Short term effects of marijuana include slowed reaction time, which may impact motor coordination, and rapid heart rate which may lead to a feeling of panic or paranoia.