Orange Oil

Safety first. Orange oils are for the air or diluted skin contact as sources describe, never for swallowing. The FDA notes that certain citrus oils used safely in food can be harmful in cosmetics, particularly on skin exposed to the sun. [1] If someone swallows any essential oil, call Poison Help at 1-800-222-1222; call 911 for collapse, a seizure or trouble breathing. [2] Bitter orange oil in particular contained large amounts of a phototoxic compound in one laboratory analysis (below). See Phototoxicity: citrus oils and sunlight.

Two oils, two names

"Orange oil" can mean two different oils.

• Sweet orange oil, usually labeled Citrus sinensis (Mill.) Pers.
• Bitter orange oil, from bitter orange, Citrus × aurantium L.

The Global Biodiversity Information Facility (GBIF) currently lists Citrus sinensis as a synonym of Citrus × aurantium, so databases and product labels do not always agree. [3] Trials and labels still use the older separate names, so this page keeps them apart and says which one each study used. The NCCIH says the bitter orange tree is native to Southeast Asia, and that its fruit, peel and essential oils are used in cooking, as flavorings and in perfumes. [4] A side-by-side view is in Sweet vs bitter orange oil.

Bitter orange dietary supplements (taken by mouth, often for weight loss) are a different product. NCCIH describes serious concerns about them, including reports of abnormal heart rhythms, heart attacks and strokes, mostly with multi-ingredient products. [4] Those concerns are not evidence about the oil.

Phototoxicity: what is known for each

In a 1985 laboratory analysis of citrus oils, lime oil and bitter-orange oil contained large amounts of oxypeucedanin, a compound that can cause photopigmentation (skin darkening) on guinea pig skin. [5] In a 2007 laboratory test using human red blood cells, orange oil (type not specified) produced moderate UVA-induced haemolysis (breakdown of the red blood cells); the authors concluded that some, but not all, fragrances show phototoxic effects in vitro. [6] NAHA (a US aromatherapy professional association, not a regulator) publishes a table that separates the two oils: it lists expressed (cold-pressed) bitter orange among photosensitizers, and lists sweet orange among its non-phototoxic citrus oils. [11] This is one association's table; it does not say which test or study it rests on, and the lab studies above did not compare sweet and bitter orange on human skin. Direct human-skin evidence for sweet orange oil, pressed or distilled: Proper evidence not found in the sources we read (we searched PubMed and the FDA, NCCIH and Poison Control pages). Distilled bitter orange oil is not covered by the sources we read. Until that is clearer, treat pressed orange oil of any kind on skin as a possible sun-sensitizer, check the maker's information and read Reading an essential oil label.

Skin irritation and allergy

Limonene is a common fragrance ingredient that readily oxidizes on exposure to air. In a US patch-test study of people already suspected of fragrance allergy, 8% (7 of 90 tested) reacted to oxidized limonene. [7] Poison Control says allergy to an essential oil is a very real possibility and that a rash means stopping the product and gently washing it off. [2] NCCIH describes bitter orange oil as generally well tolerated on the skin or in aromatherapy, which is a general statement and not a guarantee for any one person. [4] See Patch testing and what to do after a reaction.

What research shows

Aromatherapy trials are small, short and hard to blind, because people can smell what they receive. Most outcomes are self-reported.

Neither trial above shows that orange oil treats a disease. Both measured symptom scores reported by the participants, and the labor trial was single-blind, not double-blind.