Berloque dermatitis is a patch of darkened, brownish skin that appears where certain citrus oils in perfume were applied and then exposed to sunlight — it is a phototoxic reaction rather than a true allergy. Once you understand the cause, it is easy to avoid.

What Actually Causes It

The culprit is a group of compounds called furocoumarins, most notably bergapten, found naturally in cold-pressed bergamot and some other citrus peel oils. When these sit on the skin and are then hit by UV light, they trigger extra melanin production in that exact spot, leaving a streaky, often pendant-shaped mark — which is where the French name (berloque means charm or pendant) comes from, since the marks often trail down the neck the way perfume runs when it is dabbed on. You can read more about how skin reacts to fragrance ingredients in our guide to perfume allergies and sensitive skin.

Why You See It Less Often Now

Modern perfumery has largely moved to bergapten-free (FCF) bergamot precisely because of this issue, and international fragrance safety bodies restrict how much furocoumarin content is allowed in finished perfumes. It still turns up occasionally, particularly in very natural, unrestricted citrus oils used outside mainstream perfumery.

Simple Ways to Avoid It

  • Spray perfume onto clothing or hair rather than bare neck and wrists before a day in strong sun
  • Let citrus-forward scents dry fully before sunbathing or swimming
  • Save heavy citrus colognes for evenings or shaded days
  • If in doubt, check whether a fragrance lists bergamot FCF or bergapten-free on its safety data

For the wider basics of how fragrance interacts with the body, our complete guide to perfume is a good starting point.