From Will Green Tea Transform Your Hair Routine? A Derm and a Scalp Expert Tell All by Ariane Resnick, CNC for Byrdie:
"When it comes to your hair, green tea is usually more affective with topical application than if you drink it. That's because it will be going there directly, which helps deliver maximum potency to your hair and scalp in a minimal amount of time. When it comes to what exactly to use, though, you have a choice between DIY rinses and treatments or one of the many products available that contain green tea. You can try a green tea hair serum separate from your other haircare products, or choose a shampoo or conditioner that contain it in order to simplify your routine."