Yes Oatmeal is good for acne and other skin conditions and you can treat and prevent acne by eating oatmeal and making a face mask out of the oatmeal.
To make an Oatmeal Face Mask to treat and prevent acne you mix together 2 tablespoons of oatmeal, 1 tablespoon of baking soda and some water.
Then apply the oatmeal and baking soda face mask onto your face for 15 to 30 minutes and you can also use lemon juice instead of the water because lemon juice is also good at treating acne.
If you want to apply some lemon juice directly to the acne you can do so to until the lemon juice dries and then wash it off.
Doing that daily can also prevent and treat acne.