<p>Amoxicillin usually causes a full-body rash-like reaction in people with mono, so if she’s doing OK on the medicine, she probably doesn’t have mono. When I had mono a couple of months ago, I also developed ear infections, and my doctor couldn’t put me on any of the “cillin” antibiotics because of the risk of a reaction (which was only an issue since I’m allergic to the other major class of antibiotics).</p>