I first posted this in the wrong forum, I apologize.About three weeks ago my doctor put me on the generic brand of Zyrtec,Cetirizine (sp?) for allergy induced asthma. Before that I was on Symbocort but had a bad reaction.Within four days I was drinking upwards of 15 glasses of water a day and urinating maybe three times. I started experiencing excruciating bladder pain on day two. Called the doctor, they insisted I come in for a bladder infection test. It was negative for everything. I continued with the cetirizine until I was told by someone "You know those things can cause urinary retention?" I was unable to walk farther than my bed to the toilet at this point.I called the doctor he said discontinue the Cetrizine and start Singulair. I didn't start the Singulair until 6/6/14 after I could urinate and the bladder pain was gone which took two weeks to disappear.I started the Singulair this past Friday and bladder pain and burning started on Sunday, I quit taking the Singulair past Tuesday, even though my doctors insisting "You're going to have a bad asthma attack and die without it as back up." I went back to my urogyno, was tested for IC and a bladder infx and said I was negative for both although my urine was the color of Coca Cola. I was also taking meclizine, another antihistamine.I've stopped both and I'm still in severe pain. My urinary frequency is crazy now and my urethra burns all the time, my bladder hurts also. I never take meds together, in fact I try to avoid taking anything. My family doctor insists says this is gyno related and not antihistamine related and the urogyno says it's "probably" antihistamine related but that I also need to be on Premarin. I was given lidocaine to numb my urethra and told drink lots of water by the urogyno. I'm pretty sure it's antihistamine related as its now happened twice in a month and week. Has anyone experienced this?