Berloque Dermatitis

Updated: Jun 22, 2021
  • Author: Ali Alikhan, MD; Chief Editor: William D James, MD  more...
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Berloque dermatitis is a phototoxic reaction induced by exposure to long-wave ultraviolet (UVA) radiation on bergapten (5-methoxypsoralens), which is a furocoumarin known to be the only photoactive component of bergamot oil. This combination of exposure induces an intensification of melanogenesis and hyperpigmentation. Bergapten is the photoactive component of bergamot oil, which comes from the bergamot lime (Citrus bergamia) and is a popular ingredient in perfumes and fragrances. Avoidance of the offending compound is the primary goal of treatment.

Berloque dermatitis obtains its name from the German word berlock or the French berloque, meaning trinket or charm. Rosenthal [1] coined the term in 1925 to describe pendantlike streaks of pigmentation on the neck, face, arms, or trunk. He suspected they were due to fluid droplets, unaware that Freund [2] in 1916 had described hyperpigmented macules due to sun exposure after the application of eau de cologne. The phototoxic ingredient causing the pigmentation proved to be bergapten, a component of oil of bergamot, derived from the rind of C bergamia, the bergamot lime. Several cases were reported in the 1950s and 1960s following increased use of perfumes containing oil of bergamot and the passion for sunbathing. Since the introduction of artificial oil of bergamot and the reduced use of the natural product in perfumes, berloque dermatitis has become rare. Note the image below.

Hyperpigmented streaks on the dorsa of hands of a Hyperpigmented streaks on the dorsa of hands of a patient with bergapten phototoxicity




Phototoxicity or photoirritation is a chemically induced nonimmunologic acute skin irritation requiring light (usually within the UVA spectrum, ie, 320-400 nm). The skin response resembles exaggerated sunburn and does not require prior sensitization; it can be caused by a single simultaneous exposure to the chemical and light source. The photoactive chemical may enter the skin via topical administration, or via ingestion, inhalation, or parenteral administration. The reaction can be evoked in all subjects as long as the concentration of the chemical and the dose of light are sufficient. For a discussion of phototoxicty, there are several recent reviews. [3]

In the case of berloque dermatitis, the phototoxic reaction is induced by the effect of long-wave ultraviolet (UVA) radiation on bergapten, or 5-methoxypsoralens, a furocoumarin now known to be the only photoactive component of bergamot oil (see the image below). The bergapten-UVA radiation combination induces an intensification of melanogenesis and a corresponding increase in the number of functional melanocytes, which are more dendritic and dopa-positive. The distribution of melanosomes in keratinocyte changes from the aggregate to nonaggregate form.

Molecular structure of 5-methoxypsoralen (bergapte Molecular structure of 5-methoxypsoralen (bergapten)

Etiology of Berloque Dermatitis

Bergapten, or 5-methoxypsoralen, is the photoactive component of bergamot oil from the bergamot lime (C bergamia), which is a popular ingredient in perfumes and fragrances. Apart from their obvious existence in cosmetics and toiletries (such as toilet water, aftershave lotions, colognes, sunscreen lotions, moisturizers), perfumes also are found in soap, household cleaners, detergents, air fresheners, and a myriad of other everyday items.

Besides the bergamot lime, bergapten is a naturally occurring component of various other fruits and plants (see the image below). Examples of these are figs (Ficus carica), celery (Apium graveolens), lemon oil, Tromso palm (H laciniatum), Queen Anne's lace (Ammi majus), and giant Russian hogweed (H mantegazzianum). All these are capable of inducing bergapten phototoxicity, although they are not perfume-related and, therefore, classified as phytophotodermatitis rather than berloque dermatitis.

Bergapten-containing plants Bergapten-containing plants



The exact incidence of berloque dermatitis is unknown. In the Untied States, berloque dermatitis now is exceedingly rare due to the use of bergapten-free fragrance formulations. The US Hazardous Substances Act issued regulations stating that products containing oil of bergamot must not exceed 62 ppm bergapten, 2% bergamot oil. Following work performed by Marzulli and Maibach [4] and reported in 1970, even lower concentrations than this have been recommended (< 0.3% bergamot oil, equivalent to 0.001% bergapten), and bergapten-free bergamot oil is used almost always now in the Untied States. However, in some countries where bergamot oil continues to be used, berloque dermatitis remains a problem. Even in the Untied States, milder forms still are being observed. Recently, a patient was reported to have severe berloque dermatitis due to using a suntan booth immediately after applying some 40-year-old Shalimar perfume, which contained bergamot oil.

Apart from the bergamot lime, bergapten also is a component in other substances, inducing bergapten phototoxicity without the typical pendantlike appearance of berloque dermatitis. For instance, in Norway, bergapten phototoxicity has been reported due to Heracleum laciniatum and in Denmark due to Heracleum mantegazzianum (giant hogweed). [5, 6]


Precise information about racial predilection is not available.


Berloque dermatitis usually occurs in females who wear fragrances containing oil of bergamot, but males who wear fragrances or fragrance-containing products, such as aftershave lotion, also may develop berloque dermatitis.


Berloque dermatitis usually occurs in women, although it can occur in persons of any age who apply fragrances containing oil of bergamot.