A symptom of asthma includes any of the following: coughing, wheezing (a whistling sound when breathing), shortness of breath, chest tightness or pain, and difficulty breathing. These symptoms can vary in severity and may come and go, often worsening at night or early in the morning. Other signs can include rapid breathing and waking up at night due to asthma symptoms. These symptoms are caused by inflammation, excess mucus, and tightening of the muscles around the airways.