Paruresis is a mental health condition which makes it difficult for the affected person to relieve him or her self if someone else is nearby. This means that using a public restroom is highly unnerving and often physically impossible for a person who has paruresis.
Using the bathroom while away from home is something people with paruresis find themselves unable to do. Sometimes people who have paruresis have to travel all the way back home from work so they can use their own bathroom and avoid feeling anxious and embarrassed.
To see how a man with paruresis and a fear of urinals learned to overcome his anxiety, watch a video at the link provided here.
http://www.youtube.com/watch?v=kVVyZPV13S0&feature=youtube_gdata