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Good evening, I am Dr Elliot and hope I can be of help
If he is using antihistamine drops and an oral antihistamine with ongoing symptoms, then it would be time to increase to a strong anti-histamine (Fexofenadine) and increase the strength of the nasal spray to include a steroid. These will often suppress the symptoms quickly, certainly if continued with the eye drops.
It may be worth chatting with the pharmacist in the morning who may suggest something stronger that is available over the counter, but the other medication I refer to will need to be prescribed by your GP.
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