There could be swelling in the region where botox was applied. Some say that even after botox has worn off, their face still feels stiff and paralyzed. Plus, there are also less than scrupulous spas/health clinics that give botox but dont have the license or the professionals to administer the shots!
some also complain of muscle weakening where the injection was administered. there are also complaints of headaches and nausea even weeks after administration. people with certain diseases like MS should not have botox too.