Can toxic drug eruptions be caused by the consumption of herbal infusions or traditional medicines?

At the Dermatology Days of Paris 2025 conference, held from December 2 to 6 in Paris, France, Pauline Pralong, MD, dermatologist, Department of Allergology, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France, addressed this question through a series of clinical cases presented during a session titled “Toxidermias: Have You Considered Traditional Medicines or Not-So-Gentle Infusions?”

The session highlighted an often-overlooked cause of severe cutaneous adverse reactions, with clear implications for diagnosis, clinical history, and pharmacovigilance in increasingly diverse patient populations.

Pralong emphasized that clinicians should systematically inquire about herbal products, infusions, and traditional remedies when evaluating unexplained photosensitive eruptions or severe bullous dermatoses.

Furocoumarins Implicated

One case involved Marius, a 1-year-old child who developed severe systemic phytophotodermatitis after ingesting a homemade purée containing vegetables from the Apiaceae family, including parsnips, celery, and parsley. These plants are rich in furocoumarins, which are known phototoxic agents.

“The edematous bullous erythema was strictly limited to photoexposed areas, namely the face and back of the hand, with a clinical course marked by several weeks of reepithelialization and scarring,” Pralong said. “This type of photosensitization is rare and results from phototoxic mechanisms related to the oral intake of natural photosensitizing agents, which are activated by ultraviolet A radiation in sunlight.”

Another case involved a 62-year-old woman in France who developed severe systemic phytophotodermatitis after consuming an herbal infusion prepared from Chinese angelica (Angelica archangelica), a member of the Apiaceae family that also contains furanocoumarins.

“This patient presented with severe erythema and extensive skin detachment in photo-exposed areas and required hospitalization in a specialized burn center,” Pralong said. Angelica sinensis is a traditional Chinese herbal medicine widely used for its medicinal properties and is recognized for inducing photosensitivity, increasing ultraviolet sensitivity and increasing the risk for skin reactions upon sun exposure.

Black Seed Oil

Annick Barbaud, MD, PhD, professor and head of the Dermatology and Allergy Department at the Tenon University Hospital in Paris, discussed associations between severe toxic drug eruptions and traditional medicine, drawing on additional clinical case reports.

One case involved a 54-year-old woman from Nancy, France, who was urgently hospitalized for epidermal necrolysis. She presented with generalized exanthema and bullae, with skin detachment involving 20% of her body surface area. She developed Stevens-Johnson syndrome, “a condition that is typically drug related but can occur in the absence of an identifiable medication trigger,” Barbaud noted.

“The patient had ingested black seed oil derived from Nigella sativa, a medicinal plant known for its antioxidant properties but also capable of causing severe allergic reactions, including toxic epidermal necrolysis. Allergy testing identified thymoquinone as the primary allergen.”

Attribution Challenges

Another case involved a patient who developed a drug reaction with eosinophilia and systemic symptoms after taking traditional Chinese medicine, which is composed of a complex mixture of plants. “Identifying the specific causative component proved difficult, although Chinese angelica was suspected,” Barbaud said.

In several Asian countries, severe toxic drug eruptions have been reported in association with plant-based traditional medicines, sometimes when the exact composition is unknown. “These casesinclude fixed drug eruptions, flexural toxic drug eruptions, acute generalized exanthematous pustulosis, and toxic epidermal necrolysis. The difficulty in establishing causality is complicated by the concurrent use of conventional medications and traditional remedies, increasing the risk for diagnostic errors,” Barbaud said.

Traditional Medicine in Senegal, Africa

Similar challenges arise in African settings, where traditional medicines are widely used.

“In Senegal, traditional medicine is the first line of care for 82% of the population,” said Suzanne Oumou Niang, MD, Department of Dermatology, Cheikh Anta Diop University, Senegal.

“The medicinal plants used contain active compounds with therapeutic effects but also toxic potential, including alkaloids, tannins, essential oils, and other compounds. These include aromatic plants such as rosemary, sage, and thyme, as well as toxic ornamental plants such as oleander, lily of the valley, angel’s trumpet, and castor bean, which are associated with severe poisoning cases. Reported adverse reactions related to ingestion or topical application include contact dermatitis, systemic eczema, psoriasis flares, lichen planus, fixed drug eruptions, and bullous toxic drug eruptions,” Niang said.

Shea butter, neem oil, black seed oil, and aloe vera have been implicated in allergic and toxic reactions.

“To establish causality, studies have relied on allergy testing, including patch testing and prick testing with specific extracts,” said Niang. “These approaches help identify immunoallergic mechanisms and strengthen pharmacovigilance. However, plant diversity, complex mixtures, lack of labeling, and cultural practices make monitoring difficult.”

Pralong concluded that poison control centers should be contacted when severe reactions are suspected and emphasized that regulations must effectively govern phytotherapy practices to ensure patient safety.

This story was translated from Univadis France, part of the Medscape Professional Network.