About a week or so into taking Singulair for asthma and allergies, I thought it was an absolute miracle drug! I am extremely allergic to cats and when I am anywhere near them I get horrible asthma and allergies which in several cases sent me to the hospital. The ultimate test was after taking singulair I was able to spend the weekend with my friend in her small apartment and 2 cats without even a sneeze. We couldn't believe it given my past. However, it was too good to be true. Around the same time I noticed pretty dramtic hair loss. At first I just thought I was brushing too hard, I couldn't fathom actually losing my hair. However, it become so dramtic it was coming out in handfulls and I wasn't the only one to notice or be alarmed by this. I immediately stopped the medication but lost close to 70% of my hair as a result of taking singulair. I've read about this happening to others but Singulair and my doctor deny it.