Psilocybin use is not seen as obsessive or addictive. One explanation for this is that the potent experience, which may be challenging both physically and intellectually, may cause users of psilocybin to limit their use. Another reason is that psilocybin tolerance sets in very fast in humans. It is difficult to feel any effects after more than one or two days, and people require much greater doses of psilocybin after just a few days of recurrent use.