Classical presentation of recurrent prolonged cough, often with breathlessness or wheeze, suggests asthma. Demonstration of a favorable clinical response to bronchodilators and, when measurable, bronchodilation by Pulmonary function test confirms the diagnosis. A positive family history for allergic diseases or asthma, although not essential, tends to support a suspected Diagnosis of asthma.

The main symptoms and signs in asthma are cough, wheeze, tachypnea, dyspnea, and prolonged expiration. Other findings include anxiety, use of accessory muscles, monosyllabic speech, diaphoresis, fatigue, pulsus paradoxicus, cyanosis, hyperinflation, tachycardia, abdominal pain and vomiting. The symptoms may come up acutely (exposure to aero-allergen) or insidiously (following viral infections).

Asthma is mainly diagnosed by history and physical examination, but may be difficult in infants and young children. The diagnosis and estimation of asthma severity in smaller children depends on the history and response to therapy as assessed by inconstant third-party observations. In older children direct history and as well as more objective assessment is possible.