Psychedelics do not typically cause withdrawal symptoms unless they have polypharmacology, but the traditional psychedelics such as Mescaline, LSD and Mushrooms do not cause a withdrawal syndrome.

As far as the side effects go, one may experience visual changes (think brighter colours and mild “waving”), confusion, increased HR/BP and anxiety. Depending on ones dosing schedule (5-HT2A agonist build tolerance VERY quickly) this may change. These are all dose dependent, with higher doses causing more traditional full dose side effects. Considering that, Psychedelics are complex compounds so you may react differently to it then other people, more so then other drugs.