Rosemary oil is not only anti-inflammatory in nature and feels cooling on the scalp but has also been shown to increase blood flow to the follicles, boost moisture, and minimize breakage.
"rosemary oil eliminates dirt, strengthens follicles, provides moisture to the scalp, and minimizes breakage." She also credits rosemary oil with providing a "soothing quality" when applied to the scalp.
Long story short, if you suffer from a dry scalp, inflammation, and/or breakage, rosemary is definitely an ingredient to consider incorporating into your routine.

Rosemary Oil in hair care products has been shown to increase blood flow, and therefore nutrients, to hair follicles — which is the primary pathway thought to be responsible improving hair growth" and also shows that rosemary oil can help to enhance the cuticle, giving the appearance of thicker hair and pretection against breakages. Additionally, both dermatologists note rosemary's anti-inflammatory properties, which can help decrease scalp irritation and dandruff

rosemary oil "works as an antioxidant, antimicrobial, anti-inflammatory, and most importantly, a microcirculation enhancer," the latter of which "will help to reenergize the scalp for better growth.”
"rosemary oil eliminates dirt, strengthens follicles, provides moisture to the scalp, and minimizes breakage." She also credits rosemary oil with providing a "soothing quality" when applied to the scalp.
Long story short, if you suffer from a dry scalp, inflammation, and/or breakage, rosemary is definitely an ingredient to consider incorporating into your routine.