Healthy volunteers are recruited through panels fixated at Hospital de Clínicas de Porto Alegre, in Brazil, and must answer a screening questionnaire at first contact. One hundred and forty six patients who met the inclusion criteria were included and, after baseline clinical and laboratory evaluation, were randomized to receive either the active intervention or placebo, 5 times a day, at 4 hour intervals, during 48 to 72 hours, depending on patient availability to show up for re-evaluation. Patients also received acetaminophen as a co intervention, to be taken only in case of persisting symptoms.