You see caffeine withdrawal is a big thing and a very common side affect was for me was headaches during withdrawal and some other withdrawal symptoms are like brain fog plus fatigue and just having issues with concentrating period and of cause very irritability plus a study found that high intake of caffeine can cause chronic daily headaches too,and caffeine can cause like digestive issues also you see coffee can work as a laxative and if you do consume large amounts of coffee it can cause diarrhea and studies have found that beverages that have caffeine just might have something to do with GERD too,and then there is the fact that caffeine does interfers with your collagen formation so being collagen does have a direct effect on your skin maybe drinking less coffee just might mean less wrinkles too.