Natural it may be, aromatherapy is not advisable as an alternative treatment for certain groups of people.

Women in the first trimester of pregnancy as well as people with severe asthma or a history of allergies should avoid all essential oils.

Pregnant women as well as people with a history of seizures should avoid hyssop oil.

People with high blood pressure should avoid stimulating essential oils such as rosemary and spike lavender.

Individuals with estrogen-dependent tumors (such as breast or ovarian cancer) should not use oils with estrogen-like compounds such as fennel, aniseed, sage, and clary-sage.

Caution should be exercised when considering use of aromatherapy in cancer patients receiving chemotherapy.