Dermotalogist prescribed me ziana gel for acne but told me to use a small amount (size of a chocolate chip) for my entire face but why is that? help!

Can be irritating: Ziana has a chemical called tretinoin in it which is a derivative of vitamin a. If used too liberally, it can cause irritation. Therefore a pea size (or chocolate chip size) amount is all you need. Also do not go out in the sum with the gel on. For this reason, I have my patients use it before bedtime and wash it off in the morning.