Dr. Groot hair thickening serum revitalizes the scalp for thicker, fuller hair. Formulated with biotin, niacinamide, and salicylic acid, this dermatologically tested serum aims to nourish the scalp. The serum reduces scalp oil by 46% and improves hair thickness with just one use. Experience a lightweight, non-sticky finish that promotes a healthier-looking head of hair.