A dehydrated body can lead to dry skin, and this is one of the many reasons to drink water. It is very essential to drink plenty of water daily to help your overall health as well as the dryness of your skin and scalp.
Irritation of the skin are often caused by depression, anxiety and stress. Pay attention to the changes in your skin during these times and more importantly, try to avoid these feelings by applying stress reduction behaviors and techniques. Try yoga, short walks or workouts, massage therapy and diffusing lavender, for example.
To know more on stress and its relation to dandruff, click this link; https://headandshoulders.com/en-us/about/faq/does-stress-cause-dandruff