My Husband Has Not Been Going To The Restroom To

My husband has not been going to the restroom to urinate as often since Tuesday, January 3, 2017. Today, he has urinated only 2 times since 4:00 this morning. His doctor gave him RAPAFLO 8 mg per capsule to take on December 23, 2016. Today, he just informed me that he was concerned about not having to go to the restroom much after drinking fluids and eating crushed ice. Could this be a side effect of RAPAFLO? That's the only change we're aware of.
Jeraldine