Balsam of Peru is a dark, aromatic resin extracted from the bark of a tropical tree native to Central America. Despite its name, it has nothing to do with Peru. It shows up in fragrances, foods, cosmetics, and medical products, and it ranks among the most common causes of allergic skin reactions worldwide.
Where It Comes From
The resin comes from Myroxylon balsamum, a tree that grows in the coastal regions of El Salvador, Honduras, Nicaragua, Guatemala, Mexico, Costa Rica, Panama, and Cuba, typically at elevations between 300 and 700 meters. The heartland of production is a 40-mile stretch of El Salvador’s Pacific coast known as the “balsam coast.”
The name “Peru” is a geographic mistake dating back to the colonial era. European traders shipped the resin through the port of Callao in Lima, and at the time, almost anything originating from the Pacific side of the Americas was loosely called “Peruvian.” The name stuck.
To harvest the resin, gatherers carve rectangular holes into the bark, typically 25 to 28 per tree, each about 15 to 16 centimeters deep. The sap flows slowly for five to eight days. Workers collect it using clean cloths pressed against the wounds in the bark. After eight to ten days, the flow stops and must be restarted by carefully applying heat from burning torches. This cycle repeats year after year, and the trees recover well as long as harvesters avoid taking too much sap at once. An older method involves boiling young shoots and twigs in water to release the resin.
What’s in It
Balsam of Peru smells like a blend of cinnamon and vanilla, which makes sense given its chemistry. About 60 to 70 percent of the resin is cinnamein, a mixture of cinnamic acid, benzyl benzoate, benzoic acid, and vanillin. The remaining 30 to 40 percent consists of resins whose exact composition is still not fully characterized. These overlapping chemical compounds are part of what makes balsam of Peru so tricky for people with sensitivities: many of the same chemicals appear naturally in spices, citrus peels, and flavorings.
Where You’ll Find It
Balsam of Peru appears in a surprisingly wide range of products. In medicine, it has been used topically for wound care, burns, frostbite, and poorly healing ulcers, typically in formulations of 5 to 20 percent concentration. It has also been used in suppositories for hemorrhoids and in dentistry to treat dry socket, the painful condition that sometimes follows a tooth extraction. It once served as a treatment for scabies and was a component in dental impression materials.
In the food industry, the U.S. FDA lists it as an approved food additive, where it functions as a flavoring agent. On ingredient labels, it may appear under several names: Myroxylon pereirae oleoresin, Peruvian balsam, or simply balsam Peru.
The fragrance industry banned the use of crude balsam of Peru in perfumes back in 1982 through the International Fragrance Association (IFRA). However, refined extracts and distillates of the resin are still permitted and widely used in scented products including lotions, shampoos, soaps, and cosmetics.
Why It Causes Allergic Reactions
Balsam of Peru is one of the top allergens identified through patch testing, the standard method dermatologists use to diagnose contact allergies. Depending on the study, somewhere between 4 and 11.5 percent of patients tested for suspected contact dermatitis react to it. In some large European studies, it ranks among the five most common allergens, trailing only nickel and a handful of other substances. In the general population, fragrance allergy (of which balsam of Peru is a major contributor) affects roughly 0.7 to 2.6 percent of people.
The reason it triggers reactions so often is that its chemical components are shared with dozens of everyday products. Cinnamic acid appears in cinnamon and baked goods. Benzoic acid is a common food preservative. Vanillin is one of the most widely used flavorings in the world. Essential oils similar to those in balsam of Peru occur naturally in citrus fruit peel. So a person sensitized to the resin can react not just to perfume or lotion, but also to foods like spiced baked goods, citrus peel, butter toffee, ginger biscuits, certain aperitifs, and even pizza with particular seasonings.
Symptoms of a Reaction
An allergic reaction to balsam of Peru is a form of contact dermatitis. The rash typically appears within minutes to a few days of exposure, depending on the route (skin contact versus ingestion of cross-reactive foods). Common signs include an itchy rash, dry or cracked skin, bumps or blisters that may ooze and crust, and a burning or tender sensation. On darker skin tones, the affected patches often appear as leathery areas that are darker than the surrounding skin. On lighter skin, the hallmark is dry, scaly, cracked patches.
Once you stop contact with the trigger, the rash generally clears within two to four weeks. But because balsam of Peru’s chemical relatives hide in so many products and foods, identifying and avoiding the source can take real detective work.
Living With a Balsam of Peru Allergy
Managing this allergy means learning to read labels carefully and recognizing the ingredient’s many names. On cosmetic and personal care products, look for balsam Peru, Myroxylon pereirae, Peruvian balsam, or Myroxylon balsamum. Fragrance-free products are generally safer than “unscented” ones, which may still contain masking fragrances built from the same chemical family.
The food side is harder. Because the reactive chemicals overlap with compounds in cinnamon, vanilla, citrus peel, cloves, and certain preservatives, some people find relief by reducing or eliminating these from their diet for a trial period, then reintroducing them one at a time to identify personal triggers. Not everyone with a positive patch test to balsam of Peru reacts to all cross-reactive foods, so the degree of dietary restriction varies widely from person to person.
Topical medications and over-the-counter products can also be hidden sources. Some hemorrhoid creams, wound care ointments, and cough syrups contain balsam of Peru or its derivatives. Checking inactive ingredient lists, not just the active ones, is important for anyone with a confirmed sensitivity.