Instruct: Classify Amazon reviews into positive or negative sentiment
Query: side effects and non-responsive seller

This product made me feel alarmingly ill at the dose recommended, causing me to have safety concerns about which I will do some research of my own. You might want to beware of this seller --initially they not respond to my email at all, then upon sending 2 more, asking about the satisfaction guaranteed policy, they finally responded saying that once you have opened it they will not consider refunding (even though the Oxy Powder company has a money back guarantee). After that they did not reply at all to further questions on my part.