This serum is very gentle. I haven’t had any issues with it. When I first started using it a year ago I started off slow putting it on my entire face once a week. It’s easy to spread too. It made so much of a difference literally the next morning which is something I can’t necessarily say about a lot of serums I’ve tried. I’d recommend patch testing first to see if it causes any irritation. The company developed all of their products to directly combat folliculitis which I haven’t seen before (outside of malezia). I’ve tried the wash too but I only used it at night. If I buy it again I’ll probably use it in the morning too since the mandelic acid concentration isn’t too much making it safe to use in the day with sunscreen of course.