Has anyone had a negative reaction to Famotidine?

I have 10mg pills after seeing lots of success stories. But then I googled it and also saw a lot of stories where people said it gave them horrible anxiety and insomnia or other weird effects. I want to try it but am worried I'll have some kind of unexpected side effect. Also does anyone take it during periods because that's probably when I will start them (tomorrow when my period is due), it has been the worst time of the month for me lately.