The most common symptoms of bronchial asthma are episodic difficulty in breathing, which can also manifest as episodic chest tightness and coughing. During an asthma attack, there will be accompanying wheezing sounds. If the patient is more severe, they may be forced to sit up to breathe during episodes of breathing difficulties, exhibiting orthopneic breathing. Some patients may experience a dry cough or cough up a large amount of white foamy sputum. In severe cases, symptoms of hypoxia such as cyanosis of the lips and nail discoloration can occur. Asthma attacks are generally acute, with symptoms appearing within minutes, but they can also begin more slowly, worsening over several hours or days. Asthma generally relieves itself, or even after relieving, it may recur, typically worsening during the night.