Instruct: Classify the given review into positive or negative sentiment.
Query: Should have researched the side effects

I purchased this product based solely on a commercial. I followed the directions - working up from one pill each morning and afternoon to three pills each. The first week I noticed an increase in my energy level, and a loss of about 2-3 pounds. But there were negative side effects. Diarrhea was the first: then I was finding myself hungry far more often; and eventually I noticed changes in my personality. The increased energy turned into hyperactivity bordering on manic episodes, to the point of annoying my friends. I have stopped taking the pills and will be returning the unused portion for a refund as soon as I locate my receipt.