Cephalexin Monohydrate Side Effects: I was put on a 10 day course of cephalexin 500 mg. capsule therap http://www.medications.com/effect/view/22039 I was put on a 10 day course of cephalexin 500 mg. capsule therapy post-operatively. About the 6th day I started to develop a rash, however did not attribute it to the medication until I noticed that the rash started to spread with each subsequent dosing, a are you over your bout with the side effect? Wed, 18 Mar 2009 03:53:09 -0400 http://www.medications.com/effect/view/22039?item=18143 are you over your bout with the side effect? http://www.medications.com/effect/view/22039?item=18143