my daughter has been on Singulair for 4 days now. She is 2 years ...

Well, I sort of have the same problem, but I'm a teenager. My family just got over the stomach flu but I think singular might be my problem. I break out in cronic hives everday, benedryl is like my live line, and my asthma returned. So, my doctor put me on singular and my hives are even worse if I don't take Zyrtec, but like your daughter I also have loose stool. My life is already as miserable as can be because so far I've had a 14 page print out of all of my food and other items that I'm allergic to and they still don't know what I'm allergic to plus they won't give me allergy shots because I can go into anaflactic shock and there is a possibility they won't be able to bring me down.... so. If singular is something making my allergies worst I would definitley get off it.

I would not doubt that Singulair is the culprit to your daughter's issues. In regards to the asthma diagnosis, I would get a second opinion from a pulminologist (a lung specialist). Sadly, the manufacturer is either unaware of these side effects or are ignorant to them for their product. My daughter was on Singulair since the age of 2 for reactive airway disease caused by allergies or colds. I blindly gave the prescription of Singulair to my daughter by the request of both the allergist and pediatric doctor. I saw my loving little girl change into something that was not her. She became mean, complained of stomach aches, leg pains and refused to go to bed at night. She had frequest nightmares. I took the word of the doctor that this is a phase she is in (the terrible twos) and the aches and pains were easily explained away. I still gave her the medication. She started to go to school and new issues surfaced. Focus issues, not being able to complete tasks in a timely manner, easily distracted, occasional facial "tics". I figured that she was being picked on by her teacher. I requested a nicer teacher and the issues are still there. Complaints are frequent. I was ready to have her tested for A.D.D. and then I stumbled upon this site. My jaw dropped!! This is what my kid has been experiencing and what we have been seeing to-the-letter. I decided to take action and worked on taking her off Singulair. She really was not in better control of her breathing issues while on Singulair and decided to take the extra steps and sent her to a pulminologist. She is on only 1 medication instead of 4 (was on albuterol, Singulair, pulmicort and zyrtec). Her breathing is better than ever and she is slowly getting back to the loving little girl I knew before all of this mess. Her behvaior is improving, her focus is increasing and the other issues are disappearing. She has been off Singulair almost a month. I cannot say how soon all of the issues are going to be resolved because I had let her suffer for 6 years on this stuff, but I see her being happier and better every day. As I stated earlier, what you are experiencing may be a side effect and that you should get a second opinion and knowing what I have experienced, really stand up for what you are seeing and never take things as they may seem to appear. All children are different and that they can react differently. A reaction is just that, a reaction. There are other options out there.

Hoping that your child gets better.
Wishing health and happiness.