16yo boy - several years of allergic rhinitis

My 16year old boy has been suffering from what was diagnosed by his allopathy pediatrician, family doctor and ENT specialist as having allergic rhinitis (and possibly adenoids). We stay in Bangalore (which is known to many as having a climate and pollen problem that makes many children sick from cough and cold -- more compared to many parts of India).

He seems to catch cold too often, and his spells of cold last long (several weeks). He is 6'-2", of fairly lean built (from past 2yrs) and otherwise has no health issues. He seems to catch cold by taking bath or by being exposed to slightly cold/moist air. Even a slightly chilly draft triggers a bout of runny nose, sneezing, blocked sinuses. Mornings are often bad as he has to spend a good bit of time to clear his nose enough to be comfortable. Also, from time to time, he seems to have post-nasal drip causing itchy throat, where he feels the urge to clean his throat by making a strange, loud sound as if forcing air with pressure to hit the top of his mouth due to the itchy sensation.

Otherwise, he is a studious and reasonably happy child. Before Covid-19 he used to be quite active (playing intensive & fast Badminton 3-4 times a week), but now post-Covid mostly spending time at home, on online classes etc., with very little physical activity.

He himself is a little tried and frustrated with his tendency to catch cold so easily and frequently. Is there some remedy in homeopathy that might help him get over with situation ?

TIA