Hair serum is recommended to be used on the days you wash your hair because it is most effective on wet hair. However, skin experts advise against using a serum daily as excessive use may damage the hair.
The best way to use a hair serum is to take a small amount of serum and apply it on washed damp hair. This adds an extra layer of protection on your hair.
A serum can also be applied after styling the hair to make it last longer.