SS8282 - Although, rhinitis (stuffy nose, hay fever-like symptom) is a more common side effect of Risperdal (risperidone), the drug also has a significant antihistaminic effect, as a secondary effect. Some people are more sensitive to this effect than others; quite probably because they have a greater number of histamine-H1 receptors, &/or their histamine-H1 receptors are more sensitive to the effects of Risperdal.

This is usually one of those "start-up" side effects that do decrease in severity over the course of a couple or three weeks, as the body adjusts to the effects of the drug.

I hope that this is of some help. - Cam