Tizanidine
"My doctor prescribed tizandine for Migraine headaches, to relieve the tension in the neck area.  I started with a quarter pill for 4 nights, moving to half pill.  It does not make me overly drowsy or cause bad dreams (yet!).  I am working up to an entire pill. However, I have oddly begun to develop a rash.  This seems to be a rare side effect.  Unfortunately, I think I will have to discontinue use - it seems to have started working."