There is a difference between mental and physical dependence. Physical dependence means that the body protests when the substance is no longer taken. XTC has no withdrawal effects, but gradually a higher dose is required to reach the same effects. If, after a long period of not using XTC, you start using it with a high dose, the hallucinogenic effect will show up. Mental dependence means that the user gradually desires the substance more and more often and can't feel happy without it anymore. Mental dependence is possible with XTC users especially because some people can hardly do without the kicks that XTC and similar products produce.