Challenges and Pearls in Patch Testing Botanical Allergens

Conclusions

• Botanical ingredients are increasingly common in cosmetics and personal care products, but their growing use does not mean they are inherently safer than synthetic ingredients.
• A major challenge in evaluating botanical contact dermatitis is that plant-derived products are chemically complex and difficult to standardize, which makes allergy testing and ingredient identification hard.
• Most reactions attributed to botanicals should first be worked up with comprehensive patch testing for standard allergens, since fragrance, preservatives, and other common ingredients are often the true cause.
• Leave-on and wash-off patient products should be tested directly, with wash-off products diluted appropriately and interpreted cautiously because irritancy can mimic allergy.
• Repeat open application testing is an important complement to patch testing because it can reproduce real-world exposure and help confirm relevance.
• Available botanical references and databases are useful for identifying likely culprit plants and for guiding targeted testing when a botanical allergen is suspected.
• Fresh or rehydrated plant material can be tested when necessary, but only when the plant is positively identified and handled carefully to avoid irritant or toxic reactions.
• If the culprit cannot be identified, restricting botanicals from a patient’s products is a reasonable management strategy.
• Natural or organic labels do not guarantee safety, and some widely used botanicals in anti-aging and cosmetic products have documented cases of allergic contact dermatitis.
• Botanical testing should always be done with careful dilution and awareness that overly concentrated plant extracts or essential oils can cause misleading or severe reactions.