erectile dysfunction
"I'm 53, and have been using Viagra for two years. The first time I used it, I took a 100mg tablet.  The erection was rock hard and the sex was long-lasting with my wife, who orgasmed twice. But I couldn't reach orgasm, even though I was rock hard. I had the flushing in my face and a slight headache. My erection lasted a couple of hours. But couldn't orgasm. I now take 25-50 mg to reduce the long erection time, but often don't feel stimulated enough to orgasm.  I'm wondering if other men have this reaction as well."