Sudden hoarseness of baby’s voice may be caused by excessive crying, allergy or laryngitis or pneumonia. It can be treated by relieving the baby’s emotion or taking medication according to different situations. 1. Excessive crying: If a baby cries a lot, his voice may suddenly become hoarse. Usually need to pay more attention to ease the baby’s emotions, avoid frequent crying. 2. Allergy: If the baby life to certain smells, fumes or pollen allergies, contact with allergic substances allergic reaction, may lead to the baby voice suddenly become hoarse, you can follow the doctor’s instructions to use anti-allergy drugs, such as cetirizine, loratadine and so on for treatment. 3. Laryngitis: laryngeal infection after congestion, may lead to mucosal congestion and edema, the baby voice suddenly become hoarse symptoms. Need to immediately send to the doctor, follow the doctor’s instructions to be hydrocortisone nebulizer inhalation, relieve laryngeal edema, to avoid suffocation. Severe cases require intravenous use of glucocorticoids or even tracheotomy to assist ventilation. 4. Pneumonia: some special pathogens such as Bordetella pertussis infection, can appear hoarse after severe spasmodic cough, clear pathogenesis can be prescribed azithromycin anti-infective treatment. Clinical causes of sudden hoarseness of the baby’s voice more reasons, some trauma such as laryngeal nerve damage can also lead to the emergence of hoarseness of the baby’s voice, if the baby appeared the above symptoms should be timely medical treatment under the guidance of the doctor to be targeted treatment.