I took this with a sinus infection and fluid on my ears - second ...

I took this with a sinus infection and fluid on my ears - second time to take the Guaifenex for the same illness. It said very clearly on the bottle to take with a full glass of water and believe me, if you do not take with a full glass of water, the meds don't work properly at loosening up the mucos and you will get a headache. Lots of headaches are caused by dehydration anyway. But I think many of you who have complained of a headache would find if you drank more water when taking the pills, it would go away. It is also a little harder to fall asleep but no harder than it is when taking OTC Sudafed. So I would recommend the Guaifenex - it works great at breaking up the junk that causes the infections.