#1 – You’re always dehydrated
Drinking coffee can easily dehydrate your body, especially if you don’t drink water afterward. In other words, drinking up to three or four cups of coffee during the day can more side effects than increased thirst, which include: dry mouth, headaches, dizziness, dry skin, and tiredness.
Another sign to look out for in this context is frequent urination. Coffee is a natural diuretic thanks to caffeine that promotes diuresis (increased production of urine), so you may pay multiple visits to the restroom, especially if you drink a lot of coffee.