These are made by a steam distillation of the plant, which removes its oil-based chemicals into a very concentrated liquid. Essential oils are typically inhaled (for aromatherapy) or used topically; a few specific oils can be taken orally.
THE PROS: Essential oils are very potent, which means you can see benefits with just a few drops at a time.
THE CONS: “Because they are so strong, essential oils can be toxic to mucus membranes—another reason to use them in very small amounts,” says Dr. Rawls. “And never ingest an essential oil without consulting your healthcare provider first.”