Aromatherapy is the use of essential oils from plants (flowers, herbs, or trees) as a complementary health approach. The essential oils are most often used by inhilation, topical application, or ingestion, usually with warm water. Many essential oils are used in aromatherapy, including those from Roman chamomile, geranium, lavender, tea tree, lemon, ginger, cedarwood, and bergamot. Essential oils can be purchased directly, or combined by a trained aromatherapist for a more effective treatment.