First, this is very easy to use.
Second, you don't need a lot...just a thin layer on each tooth.
Finally, I have experienced no irritation of the gums.
I've used this now for about 2 weeks, and I have definitely noticed a difference and my teeth are really white now. I also had one tooth that (because of a root canal decades ago) was noticeably different in color than my other teeth. Sometimes, I will only put gel on that tooth. It is now NOTICEABLY closer in color to my other teeth = )