I was prescribed Biaxin XL for URI about 5 days ago. The first couple nites of taking it I didn't notice any side effects b/c I was also taking a cough syrup. The past 3 nights though I have had insomnia. I sleep for like 3 hrs and then just lay there wishing myself to sleep for the rest of the nite. Then during the day I have no energy and terrible headaches from my lack of sleep.