Lundh K, Gruverger B, Persson L, et al. Oral provocation of patients allergic to sesquiterpene lactones with German chamomile tea in order to demonstrate a possible systemic allergic dermatitis. Contact Dermatitis. February 22, 2020. doi: 10.1111/cod.13499.
Systemic allergic dermatitis traditionally refers to a skin condition where a person who is sensitized to an allergen through skin contact will react to that same allergen through a systemic route. The condition has been demonstrated in patients with an allergy to certain metals, medications, and herbal products. Patients with a contact allergy to the daisy family (Asteraceae) often report worsening or a flare-up of vesicular hand eczema after ingestion of sesquiterpene lactones. The purpose of this randomized, double-blind, placebo-controlled trial was to investigate whether German chamomile (Matricaria chamomilla, Asteraceae) tea can provoke systemic allergic dermatitis in patients hypersensitive to a sesquiterpene lactone mix (SLM).
Of the 45 patients from southern Sweden with a contact allergy to SLM recruited for the study, 35 (26 women and nine men, mean age 59 years) agreed to participate. An additional 22 patients (17 women and five men, mean age 52 years) without a contact allergy to SLM were recruited as controls.
The investigative period lasted 45 days and included six visits at the researchers' department in Malmö, Sweden. There were three visits in the first part of the study from day 0 (D0) to D7, and three visits in the second part from D42 to D45. On their first visit (D0), all participants answered questions regarding plant exposure, history of atopic dermatitis, asthma or hay fever, medication use, or if they experienced worsening of their hand eczema with the ingestion of coffee (Coffea arabica, Rubiaceae), chocolate (Theobroma cacao, Malvaceae), potatoes (Solanum tuberosum, Solanaceae), herbal tea, beer, or lettuce (Lactuca sativa, Asteraceae). They also received an examination of their hands by a dermatologist and patch-testing.
For the patch test materials, an aqueous extract of tea made from German chamomile was prepared and diluted with water to 32.0% per volume, 10.0% per volume, 3.3% per volume, and 1.0% per volume. The dried flowers were acquired in a health food shop, and the authors note that it was not possible to confirm the botanical identify and quality. The other tests included a petrolatum preparation of German chamomile 2.5% per weight, Roman chamomile (Chamaemelum nobile, Asteraceae) 1.0% per weight, and sesquiterpene lactone parthenolide 0.1% per weight. Also tested was SLM 0.1% per weight, containing alantolactone 0.033% and a combination of costunolide and dehydrocostus, each 0.033%. Test preparations of German chamomile were provided by Trolley; Hermal; Reinbeck, Germany, and the remaining preparations by Chemotechnique Diagnostics; Vellinge, Sweden. The 35 SLM-positive participants were tested percutaneously with thin layer chromatograms of German chamomile tea, and the 22 controls were tested with blank strips without the tea. The chromatograms in all 57 participants were attached on their back and removed after 48 hours. The tests were analyzed according to the International Contact Dermatitis Research Group on D3 and D7.
Three participants with contact allergy to SLM dropped out after the patch test. Two of the three participants experienced worsening of hand dermatitis after drinking herbal tea. Two of the controls demonstrated hypersensitivity to chamomile tea extract and subsequently joined the test group, leaving 34 participants (26 women and eight men, median age 59 years) in the test group and 20 controls (15 women and five men, mean age 51 years). Participants in the test group were randomized to receive six, 175 mg freeze-dried German chamomile tea capsules corresponding to three cups of tea, or six placebo gelatin capsules containing lactose. The SLM-negative controls received chamomile tea capsules.
Participants were to rate the severity of their hand eczema, and their hands were investigated by a dermatologist before the oral provocation and 24 and 72 hours after. The participants were also asked about redness, itching, and eczema from other parts of their body. The oral provocation took place in the morning of D42, and the participants were instructed not to consume anything but water six hours before provocation or 30 minutes after.
Hand dermatitis was present in 32 participants at time of oral provocation. Of the 32 participants, 15 with a contact allergy to SLM were provoked by chamomile tea and 12 by placebo. Five of the participants in the control group had hand dermatitis. Localization of the hand dermatitis to the palms was noted in 22 of the SLM-allergic participants and in two controls. Hand dermatitis was more common in SLM-allergic participants who were provoked by chamomile tea (P < 0.001) and placebo (P = 0.009) compared with control.
Among the SLM-positive participants, 6.0% had occupational contact with plants, and 62.0% had plant contact from leisure activities. Among the controls, 5.0% had occupational contact with plants, and 45.0% had plant contact from leisure activities. A history of atopic dermatitis was reported in 44.0% of participants hypertensive to SLM, German chamomile tea, or both, and in 30.0% of controls. Participants hypersensitive to SLM, German chamomile tea, or both, reported a history of asthma or hay fever, and 56.0% of SLM-positive participants reported a history of atopic dermatitis, asthma, or hay fever. Worsening of hand eczema was reported only by SLM-positive participants for food and beverages.
Of the 35 SLM-positive participants originally included in the study, 88.0% tested positive to SLM. A positive patch test reaction to the water extract of chamomile tea was demonstrated by 86.0% of the SLM-positive individuals, and 9.0% of the SLM negative controls. The controls, who were tested with blank strips, did not experience any reaction, while 43.0% of the SLM-positive participants patch-tested positively to one or more spots on the chromatogram with German chamomile tea.
No flare-up reactions of healed patch test reactions were observed for nickel, SLS, or German chamomile tea 24 or 72 hours after oral provocation with German chamomile tea capsules or placebo for any participant. Fifteen participants (10 provoked with chamomile tea and five with placebo) who had positive test reactions to the chromatogram experienced no flare-up of the healed test reactions of the thin-layer chromatograms. The physical examination by the dermatologist revealed no flare-up of previous hand dermatitis at the time of oral provocation. Oral provocation worsened hand eczema in 15 participants (14 with and one without contact allergy to SLM). For participants with contact allergy to SLM, no significant difference was found between those provoked with tea or placebo. Of the participants with a contact allergy to SLM, chamomile tea, or both, 24.0% reported redness, itching, and eczema from body parts other than their hands.
Based on their findings, the authors conclude that there is no evidence suggestive of systemic allergic contact dermatitis for SLM-positive individuals. Nonetheless, the authors advise that SLM-allergic patients avoid or restrict sesquiterpene-containing foods like herbal teas and lettuce.
The authors report no conflicts of interest.
–Gavin Van De Walle, MS, RD