Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns.
As per your complain
excessive salivation in kids can be due to causes like
throat infection, sinusitis,
peritonsillar abscess, oral infections,
mouth breathing,allergies, side effect of medication if he takes any,multiple sclerosis, autism, downs syndrome etc..
You should consult a Medicine specialist and get evaluated and a through clinical evaluation and investigation as per suspected cause can help in diagnosis and treatment can be planned accordingly..
As of now make him gargle with antiseptic mouthwash as it has a drying effect in mouth and will relieve dryness.
Brushing teeth 2 to 3 times a day can help..
If he is a mouth breather, teach him breathing through nose and encourage him to keep his lips closed and can also be given a mouth guard to enforce
nasal breathing..
Avoid giving him high sugar foods as they tend to increase salivation..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.