Urso is very safe and overall interacts very well with other drugs. The one drug it can interfere with is when someone also takes cholestyramine for the itch.
This drug is the first line treatment for itch. Its action is that it binds to the bile acids in the bowel and carries them out of the body. Since bile acids irritate the nerves in the skin causing the itching, then the binding of the bile acids and eliminating them from the body helps the itching.
But.. Urso is a bile acid itself. It can also bind with the cholestyramine and both be eliminated. Dr. Jones recommends that the Urso be a single dose taken in the evening and the cholestyramine be taken in intervals throughout the day.