Did you decide to stop taking it after advising your psychiatrist, or of your own volition? 

If you have the backing of a medical professional for this decision, and if the side effects are going to be intense (they sound pretty serious), then maybe you should consider going on medical leave while you sort yourself out.

If however, you're going to keep going in to the office, then you may indeed wish to inform your boss and/or HR. 

This situation is tricky because you would be voluntarily disclosing medical information. However, if you suddenly snap and yell at someone in the office it might not hurt for your boss to be aware that you don't "mean it", and might need some time alone to compose yourself, or to head home for the remainder of the day.

Either way, I would strongly suggest taking a few days off and monitoring your reaction to the withdrawal.