http://www.medications.com/effect/view/38273 WHEN I USE ALLEGRA D I USE 1/2 DOSE OF A 12 HR. PILL. I CANNOT HAVE SEX WHEN USING THIS DRUG. I CANNOT HAVE AN ERECTION. I ALSO HAVE PROBLEMS URINATION. NO PAIN JUST WON'T COME OUT MUCH.....MAKES ME VERY THIRSTY ALSO.....BUT IT SURE DOES THE JOB WITH THE S