Ways to Use Onion Essential Oil Take a moderate amount of aloe vera and mix four to five drops of onion essential oil. Apply it to your body to detoxify your skin and to remove spots and fine lines. To improve your hair’s condition and promote new hair growth, mix three drops of onion essential oil with your conditioner and shampoo. Apply the mixture to your hair roots and tips. You can also mix two to three drops of onion essential oil with five drops of Coconut Carrier Oil and apply it to your hair. Follow the procedure thrice a week. Mix three to four drops of onion essential oil in a steam diffuser or an inhaler to clear your respiratory tract. You can also add five drops of onion essential oil in boiling water and inhale it whenever you suffer from a cough and cold.