Enlarged adenoids may be caused with recurrent adenoiditis, rhinitis-sinusitis, acute tonsillitis and other diseases. 1. Adenoiditis: same as acute tonsillitis, mostly due to bacterial or viral infections, such as hemolytic streptococcus B, adenovirus, influenza virus, parainfluenza virus and enterovirus. 2. Rhinitis – sinusitis: caused by viral or bacterial infection or allergy, common symptoms include nasal foreign body sensation, nasal congestion, sneezing, increased secretion, etc. Repeated stimulation of secretion can cause adenoid hypertrophy. 3. Acute tonsillitis: the common causative agents of this disease are bacteria, viruses, Chlamydia trachomatis, Mycoplasma pneumoniae and so on. It can be triggered by harmful gas stimulation, lowered temperature, excessive smoking and alcohol. Some patients with recurrent or prolonged disease may cause adenoid hypertrophy. To summarize, there are many causes of adenoid hypertrophy, and it is necessary to go to the hospital for consultation to clarify the cause of the disease.