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Míriam Araújo1; Cátia Alves1; Sara Prates1; Paula Leiria Pinto1,2

1. Immunoallergology Department, Hospital Dona Estefânia, CHULC, EPE, Lisbon, Portugal
2. CEDOC, Integrated Pathophysiological Mechanisms Research Group, Nova Medical School, Lisbon, Portugal

Reunião Internacional, apresentação sob a forma de comunicação oral e sob a forma de Poster – EAACI Congress, 1 a 5 de Junho de 2019, Lisboa

Caso Clínico:
Introduction: Hypersensitivity reactions (HSR) to folic acid are rare and chronic urticaria induced by folic acid rich foods is even more rarely reported.
Case Report: A 36 year-old female patient was referred to our department due to exacerbation of chronic urticaria after ingestion of strawberries. As comorbidities, we highlight a radicular syndrome, with the need of chronic pain medication (gabapentin and cyclobenzaprine), and a severe lung emphysema due to tobacco. Since 2016 she had frequent episodes of urticaria with no evident trigger, denying worsening with anti-inflammatory drugs. In addition to the exacerbation of urticaria following the ingestion of strawberries, she also reported one reaction to folate supplement with dyspnea, facial edema and generalized pruritus and erythema 15-30 minutes after taking one 5 mg tablet. She recurred to the emergency department, where only a generalized pruriginous exanthema was described, with no other findings in physical examination. She received treatment with antihistamines and corticosteroids with symptom resolution and she never took folate supplements again. We assumed the diagnosis of chronic spontaneous urticaria and, in order to investigate the hypothesis of concomitant drug allergy, we performed an oral drug challenge with folic acid. Thirty minutes after ingestion of the first dose (1mg), the patient developed generalized urticaria, with no other manifestations - 10 mg cetirizine and 40mg prednisolone were administrated with resolution of the symptoms within three hours. Skin prick test and specific IgE to strawberry was negative. She was given indication to avoid folic acid supplements and supplemented food or drinks and, since then (7 months follow-up), she had only one more episode of urticaria, related to the ingestion of broccoli and beans, which are folate rich foods, such as strawberries.
Conclusions: The presentation of this case is relevant because folic acid HSR are very rarely described as a cause of chronic urticaria. These findings should raise awareness for possible immediate allergic symptoms caused by folic acid-containing foods in patients with folic acid allergy.

Palavras Chave: folic acid allergy