There are four major symptoms to identify whether someone has asthma. Firstly, persistent cough, especially if it gets worse late at night and early in the morning. Secondly, wheezing, which is a whistling sound that occurs while breathing. Thirdly, tightness of the chest, which feels like somebody is squeezing the chest. And finally, shortness of breath, which is basically finding it difficult to breathe or feeling out of breath without any apparent reason.