Asthma is a chronic disease of the lungs in which a person has sudden attacks of shortness of breath, wheezing and coughing. It is one of the most common diseases affecting respiration. It affects all races and both sexes equally. It usually begins in childhood or early adult life. Asthma is caused by a blocking of the bronchial tubes in the lungs. This blocking is caused by shrinking of the bronchial muscles, swelling of membranes lining these muscles and the presence of thick mucus called phlegm. Allergic bronchial asthma is the most common type of the disease. It is caused by adverse reaction to things like house dust, pollen, feathers, animal dandruff, drugs and certain foods. Strong odours or smoke may also cause its attacks. Asthma is often linked with hayfever, another type of allergy. Different kinds of asthma may even harm other parts of the body. Asthma attacks often occur after heavy physical work or in case of emotional disturbance. An infection of the nose and throat can trigger off an attack. A drastic change in the weather may also prove troublesome in this regard. Exposure to sudden changes in temperature and humidity or both may also cause an attack. Common symptoms of asthma are wheezing, a sense of suffocation, dry cough and an inability to expel air easily from the lungs. Asthmatic attacks usually last for half an hour to several hours. Prolonged or frequent attacks may prove dangerous if the patient is weak or suffers from malnutrition. Some 35% - 40% of childhood asthma cases improve at puberty. A physician identifies asthma by physical examination and allergy skin tests. From these tests, the substance to which the patient is allergic, can be detected. Most doctors usually prescribe drugs, such as epinephrine or ephedrine, to treat it in the initial stages. Patients with very serious cases of asthma however may need to take ACTH or cortisone. Some doctors prescribe small doses or injections of asthma-causing substances. And they slowly increase the strength of these injections until the patient’s body develops a natural resistance to the allergic substances. Sometimes oxygen becomes essential for such a patient. To avoid asthma attacks, one should avoid substances to which one is allergic and the situations that precipitate attacks.