Citrus bergamia (synonym: C. aurantium bergamia) is a small tree in the citrus family, native to the Italian region of Calabria. The tree bears small, round to pear-shaped fruits known as bergamot oranges. Bergamot is a highly regional crop: The Calabrian coast produces 90% of the world supply of bergamot.^[7] Bergamot should not be confused with “wild bergamot” (Monarda fistulosa), a totally unrelated herb in the mint family.

Bergamot essential oil (BEO) is the peel oil of the bergamot fruit. The oil has a distinctive and pleasant aroma, recognizable as the characteristic scent of Earl Grey tea. This oil has a long history of use in medicine, perfumery, and food and is now widely used in aromatherapy.^[8][9] Historically, bergamot oil was used as a treatment for conditions as varied as wounds, burns, toothaches, scabies, and insomnia and as an anti-inflammatory, a sedative, and an antimalarial.^[10]

Bergamot oil can be extracted by pressing and/or by distillation, and its composition depends on the extraction method and on whether any further processing was done to remove or isolate various constituents. Therefore, several preparations of bergamot oil exist, including:^[8][11]

Note: BEO-MHF may also be referred to as “terpeneless BEO,” “deterpened BEO” or “folded BEO”. Terpenes like limonene and β-pinene are major components of BEO but contribute relatively little to its fragrance; removing them concentrates the more aromatic components.^[11]

The rest of the bergamot fruit has historically found few uses, but over the last decade, bergamot juice, peel and/or pith extracts have attracted increasing research attention.^[7]

While bergamot oil’s distinctive, delightful odor can (and should!) be enjoyed for its own sake, it is also used in aromatherapy.^[9] Bergamot essential oil (BEO) aromatherapy has customarily been used for anxiety relief and to produce a calming effect.^[12]

BEO aromatherapy has been studied for relaxation, medical anxiety, job-related stress, pain relief, depression, and sleep quality. There is limited evidence that it may promote relaxation in healthy adults who are not in stressful situations;^[5][13][14] may reduce presurgical and postsurgical anxiety in adults^[15][2] but not in children;^[3][16] might reduce adults’ feelings of job-related stress or burnout, although more research is needed;^[17][18] might improve sleep in adults when inhaled at night, although more research is needed;^[1] and might have some beneficial effect on mood in postpartum women, although more research is needed.^[4][6]

The main drawback of bergamot oil is photosensitivity (sensitivity to light). Cold-pressed bergamot oil contains a phototoxic constituent, so skin topically exposed to bergamot oil may become very photosensitive, developing itching, redness and dark pigmentation — and in some cases, even burning — when exposed to ultraviolet light. The culprits are psoralens found in the cold-pressed oil (primarily bergapten, a phototoxic psoralen also known as 5-methoxypsoralen (5-MOP) or bergamot camphor).^[19][20] Further, it’s possible for the phototoxic psoralens found in BEO to induce skin cancer after exposure to ultraviolet light. Because of bergapten’s phototoxicity, the International Fragrance Association recommends that the concentration of bergamot oil in products applied to sun-exposed skin be limited to 0.4%, targeting a maximum of 15 ppm of bergapten in the final product.^[8] Therefore, when applying bergamot oil to any skin that may be exposed to the sun, care should be taken to use only bergapten-free bergamot oil, even if there will be a few days between bergamot use and sun exposure. There have been case reports of people who have developed phototoxic skin reactions (burning, blistering) after using bergamot-containing preparations, such as bergamot massage oil, directly on the skin, and then spending time in the sun 48–72 hours later.^[9]

An animal study has found that bergamot essential oil (BEO) calmed HPA axis activity.^[15] While its mechanism of action is not completely understood, BEO may increase the extracellular (outside of the cell) concentrations of some amino-acid neurotransmitters; another animal study found that rats who’d been systemically administered BEO had higher extracellular concentrations of aspartate, glycine and taurine in their hippocampi.^[15][21]

Further, some of the specific components of BEO have demonstrated positive properties in isolation. BEO contains linalool (6–15%) and linalyl acetate (23–35%).^[8] Linalyl acetate, which is also found in lavender essential oil, has been shown to promote vascular smooth muscle relaxation in animals.^[4][22] Linalool has demonstrated anticancer, antimicrobial, anti-inflammatory, antianxiety, antidepressant, and analgesic properties in vitro.

The 5-methoxypsoralen present in cold-pressed BEO may increase plasma melatonin concentrations; melatonin regulates the sleep/wake cycle, which could contribute to the effects of BEO on sleep quality.^[4]