4-year-old children breathing loudly can be seen in physiological phenomena, respiratory tract infections or rhinitis and other conditions, whether it is normal need to be analyzed on a case-by-case basis, such as exercise can occur after breathing loudly, is a normal phenomenon. 1. Physiological phenomenon: such as children after exercise can appear breathing sound, is a normal physiological phenomenon, can be relieved after rest, or children in the nasal cavity has more secretions, not clean up can also appear the above performance, as appropriate, clean up can be relieved. 2. Respiratory tract infections: such as acute upper respiratory tract infections, clinical nasal congestion, can affect the respiratory situation, the phenomenon of heavy breathing, breathing sound, some children’s body temperature rise can make the above symptoms worse, accompanied by increased respiratory frequency, belong to the state of the disease, the need for timely intervention. 3. Rhinitis: often referred to as inflammation of the nasal mucosa, clinical symptoms can be manifested as nasal congestion, runny nose, the phenomenon of loud breathing, some may appear at night snoring, open-mouth breathing, is an abnormal situation, need to be treated. 4. Other: children with adenoid hypertrophy may have the above phenomenon, which is abnormal. It is recommended to consult a specialist if necessary to determine whether it is normal or not.