Yes. I recently completed a 10 day regimin of Nitrofurantoin for a UTI. On the 8th day I started having very itchy palms and feet, then began a rash in my groin and wrist area. I started taking Benedry, and it made most of the symptoms go away. After 6 days the rash and itching were gone. After 2 days it came back with my hands not only itchy, but very red, as well as my feet. A rash appeared on my chest, and then turned to welts. I started thaking Benedryl again, and it is better now. How long must I take it? Also, how long does Nitrofurantoin stay in your body?