There are many uses of serum for hair. These include reducing frizz, detangling it, and providing it with additional hydration and nourishment that makes your hair feel strong and healthy. Hair serums also help deflect environmental pollutants when you step out and thus protect your hair.16 Dec 2022 Daily conditioners add nourishment, detangle, and soften the hair while moisturizing the scalp. Serums can target either the hair or scalp and are meant as a leave-on treatment.