I'm only guessing it would be severe since I don't know.  My brain slows down and gets sluggish when I've gone too long without a dose.  I have been cutting the 30mg pills in half for about 8 months now to stretch it out through the day.  I never felt a "high" feeling from this medication, only a slight skin crawling.  My brain is my moneymaker, so I couldn't take anything that actually made me dizzy.  Most people don't believe me when I say that, but that's somewhat irrelevant since the other side effects of the medication is preventing me from getting better.