Trihexyphenidyl (Artane, Apo-Trihex, Parkin, Pacitane) side-effects

I take Pacitane 2mg for EPS. But I am having drowsiness. When I talked to my psychiatrist about it he said it won’t cause drowsiness. And it has stimulating effect. I have read on many websites that Pacitane can cause drowsiness. How do tell him that?
Anyone with similar experience here? Drowsiness?