I am 32 y male. I diagnosed with ulcerative colitis 6 months ago. Now i m in remission with having Measacol 2.4 g/ day orally. I was suffering from ED too. So urologist suggested me to do Doppler test of penile vessel for which I need to take viagra 100 mg once. Now I am afraid that if Viagra 100 mg once can flare up my Ulcerative colitis???? Brothers do you have experience taking Viagra while having Ulcerative colitis??? It Viagra safe for UC?? Please help me.