I am a 49 year old female. I started taking Singulair for grass allergies. Went to the DR. for a physical and blood work came back for elevated Liver Enzyems. According to WebMD this is a common side of effect of this drug. The other things that was happening was odd pains in my head. Not headache but sharp pains on the sides of my head. This too is a side effect of this drug. I stopped the drug and everything went back to normal.