 The antihistamines with inhaled steroids are the cornerstone on the symptomatic therapy in the management of patients with rhinitis and the first line of treatment in patients with urticaria. Currently, the use of antihistamines has become popular due to its excellent safety profile and clinical efficacy, however to the investigators knowledge, there are no studies about the pharmacokinetic and pharmacodynamic effects of these drugs in patients of tropical Latin America. The investigators main interest is to evaluate if skin test inhibition correlates with the clinical effect of five anti-histamines. 