headache is a very common side effect with any diet, but it is especially magnified with keto diet due to the daily low carb intake and dehydration. I personally remembered having massive headache in my first three days on keto diet. I was in nursing school at the time. I told my professor that something was wrong with me and that I needed to go to the emergency room. I went to the emergency room, had a CT of the head done, but nothing was wrong as I was told (after incurring more than 4,000 in emergency bill). I went back home disappointed because I was convince something was wrong. I finally spoke with my friends that were on the same keto diet with me and they told me to just drink water and see what happens. I drank more than 2 liters of water that day my headache disappeared. As a beginner, you might experience headaches, irritability, confusion, and just plain having a feverish feelings, but all these symptoms usually go away after few days. So how do you take care of this headaches? well it is simple, drink enough water. Water is your best friend not just for few days on keto, but the entire time you are on the diet. Do drink at the very least 2,000 liters of water everyday. Water will help prevent dehydration, prevent or minimize the headaches, and keep you feeling full. Next is bad breath.