Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Beware of long term use

Arrived in good time and in good condition. I use it to help me sleep. 450 mg. keeps me feeling exhausted and weak for the entire day following use. 225 mg. or less seems to work fine. Long term it causes painful gastrointestinal issues and is quite likely responsible for reducing my white blood cell count.Safety and dosage information on it is hard to find. It is not FDA approved, and obviously a powerful medication. At times I find it a necessary evil. For short term use, it did allow me to get some sleep. Insomniacs: please use with extreme caution!