Trigger and risk factors in asthma are multiple, the most relevant at the time are: genetic, infectious (viral, bacterial, fungi and parasites), environmental (allergens, smoking, irritants, pollutants of cars, industries, work environment, etc.) and obesity. Asthma severity meets influenced by the age, sex, pregnancy, immunological system immaturity and the atopic march. The pathogeny of the inflammatory allergic process more than an imbalance Th1/Th2, mast cells, eosinophils and IgE, today includes the important participation of other elements such as: Th17 or IL-17, IL-23, IL-25, IL-27, Tregs, TLRs, NODs, MAs, DCs, bronchial epithelial cells, chemokines, neurokinins, ICAM-1, NO (iNO). Besides other elements that influence the inflammatory response amplification and the remodeling of the airway epithelium.