Clinical aromatherapy is an alternative medicine therapy that can be beneficial in the inpatient or outpatient setting for symptom management for pain, nausea, general well-being, anxiety, depression, stress, and insomnia. It is beneficial for preoperative anxiety, oncology, palliative care, hospice, and end of life. Essential oils can be dangerous and toxic, with some being flammable, causing skin dermatitis, being phototoxic with risk of a chemical burn, or causing oral toxicity or death. The article investigates history, supporting theories, guidelines, plant sources, safety, pathophysiologic responses, and clinical nursing aromatherapy. Recommendations for developing a best practice clinical nursing aromatherapy program are provided.