Can loperamide cause constipation?

Absolutely yes.. This medicine slows down your intestinal motility, reduces fecal volume and increases viscosity, thus it can cause constipation if you are senstive to it or over using it. It is often used to treat diarrhea, short-term use. Stopping it should resolve your constipiation in a couple of days if it is causing your constipation. Consult doc if severe/persistent. Good luck.
Yes it can. Loperamide is a locally acting narcotic that slows down the bowel and can certainly lead to constipation with high doses or chronic use.