Contact dermatitis in children is frequently misdiagnosed. Skin infections and autoimmune disorders are often proposed as alternative diagnoses. In addition, cosmetics formulated with natural compounds are commonly and increasingly used by parents, who may underestimate their potential adverse effects. We report the first case of copaiba balsam-induced contact dermatitis in a child. A 6-year-old girl was hospitalised for non-febrile dermo-hypodermitis of the leg with oedema, associated with progressive, diffuse erythematous papular lesions unresponsive to 48 h of amoxicillin-clavulanate therapy Small papulovesicular lesions and skin infiltration were noticed on the leg (Figure 1). Wells' cellulitis was considered. History revealed a homolateral erythematous-squamous plaque 2 weeks earlier, which had been treated topically with an emollient, a topical corticosteroid and topical econazole without improvement. Laboratory findings showed mild eosinophilia (up to 1 Giga/L) and a normal C-reactive protein (CRP). Skin biopsy of the leg suggested a post-insect bite lesion. The condition improved with topical corticosteroids. Following a diagnosis of contact eczema (not initially suspected), further history revealed the application of copaiba balsam (Guayapi Baume Copaiba, 100% Copaifera officinalis resin balsam) to the initial plaque, a product occasionally used by the family for its supposed healing properties. Patch testing with the European baseline series, additional allergens (all from Chemotechnique) and the patient's own products was performed. At 72-h and Day 7 readings we observed strong positive (++/+++) reactions to copaiba balsam 1% in petrolatum and to colophony; a moderate positive (++) reaction to copaiba balsam 0.1% in petrolatum; a weak to moderate positive (+/++) reaction to Puressentiel Anti-Pique/Anti-Sting Roll-On (Figure 2); and weak positive (+) reactions to Peru balsam, fragrance mix I, compositae mix II, linalool 1%, limonene 0.3% and limonene 0.2%. Repeated open application tests with Avène Cicalfate Restorative Cream, econazole Biogaran1% Crème and Locoid Hydrocortisone Butyrate 0.1% Crème were negative after 10 days. Copaiba balsam is an oleoresin produced by incision of the trunk of various species of Copaifera L.(fam. Fabaceae) native to the Amazon region. The oleoresin, which is rich in hydrocarbon sesquiterpenes (non-lactones) and diterpenic acids, has traditionally been used locally as a healing agent and as an anti-haemorrhoidal agent but also orally for its numerous other supposed medicinal effects 1, 2. The product in this case (Guayapi Baume Copaiba) is described on the manufacturer's website (https://www.guayapi.com/nos-produits/baume-de-copaiba accessed Dec 2025) as being derived from ‘Copaifera officinalis’, but on the website of one of the distributors of the product (https://www.easypara.com/guayapi-baume-de-copaiba-bio-50ml.html accessed Dec 2025) is claimed to be derived from ‘Copaifera guianensis’. It is quite likely that the manufacturer of the product (Guayapi) has not carried out any quality control or quality assurance through which the botanical source is formally identified, nor will the chemical composition have been checked in a laboratory against a published quality standard. The sesquiterpenes (volatile fraction) and diterpenes (resinous fraction) of the oleoresins are known to vary qualitatively and quantitatively between Copaifera species. However, the principle sesquiterpenes present in the product were probably α-humulene, β-caryophyllene and β-caryophyllene oxide 1, 2. The positive reactions to colophony and Peru balsam may be due to cross-reactivity or co-sensitization to tree resins. Indeed, a recent study demonstrated that caryophyllene oxide and β-caryophyllene are potentially allergenic constituents of colophony 3. Moreover, sensitizing oxidation products can form during air exposure of β-caryophyllene, similar to the hydroperoxides of linalool and limonene, leading to potential skin sensitization 4. Finally, in a previous study, all patients with positive reactions to the rare fragrance sensitizer β-caryophyllene also reacted to colophony, and cross-reactivity between essential oils and Compositae species was related to plant extracts from the Compositae mix rather than to the pure sesquiterpene lactones of the standard series, consistent with our findings 5. Although historically well-recognised as frequently causing an erythematous, papular, urticarial, vesicular, petechial or bullous drug eruption known as ‘copaiba rash’ following oral administration 6, this is the first reported case of contact dermatitis due to copaiba balsam. Diagnostic delay, resulting from unreported topical product use and lack of clinician awareness of contact allergy, led to unnecessary hospitalisation and skin biopsy. Families should be informed of the potential risks associated with the use of topical products marketed as healing or anti-inflammatory agents. Nathalia Bellon: conceptualization, investigation, writing – original draft, writing – review and editing, validation, data curation. Angéline Girault: investigation, data curation. Morgane Seyler: investigation. Annonciade Frassati-Biaggi: investigation. Anne Welfringer: investigation. Christine Bodemer: investigation, validation. The authors have nothing to report. The parents patient in this manuscript have given written informed consent to the publication of the case details and photographs. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
Bellon et al. (Mon,) studied this question.