Systemic allergic dermatitis caused by sesquiterpene lactones.

Patients with Compositae sensitization are routinely warned against the ingestion of vegetables, spices, teas and herbal remedies from this family of plants. The evidence for the occurrence of systemic allergic dermatitis caused by sesquiterpene lactone-containing plants is mostly anecdotal and based on statements from patients rather than scientific data. However, a few clinical reports on accidental sensitization and exposure and oral challenge prove the existence of this kind of reaction, most convincingly for strong contact allergens such as costunolide in bay leaves, and less so for weak allergens such as those of lettuce. Other Compositae species suspected of causing systemic reactions are artichoke, mugwort, yarrow, dandelion, feverfew, and elecampane. Some Compositae vegetables and teas, such as lettuce and chamomile tea, may induce systemic reactions through both humoral and cell-mediated mechanisms. It is difficult to disentangle the contribution of these reactions to both local and systemic symptoms of skin and mucous membranes in, for example, lettuce contact allergy. Further studies are needed to assess the prevalence of systemic allergic dermatitis caused by sesquiterpene lactones, and to clarify the pathogenesis for individual haptens.