Onion Hair Oil. nsb Herbals onion hair oil is a nourishing hair fall treatment with real onion & hibiscus extracts which controls hair fall and promotes new hair growth. HOW TO USE: – To Apply the nsb Herbals onion oil for Hair Growth, take this oil on your finger tips, and massage gently onto the roots of your Hair. Try and practise this step at night so that the oil penetrates deep onto your Hair Follicles. Post leaving overnight.