I don't take Rebif but I know if I take Motrin on an empty stomach I tend to get acid reflux so I always make sure to eat a little something first even if it's just a slice of bread and glass of milk. I've always had trouble with acid reflux though, went to ER once because I thought I was having a heart attack found out it was spasms of the esophagus. I'd call the dr. just to be sure. Hope you find relief soon, I know it can be terrible to deal with.

Susan