My allergy symptoms persist despite the daily intake of Loratadine 10 mg started 3 weeks ago. I have tried to replace Loratadine with other antihistamines, but without success. What should I do?

If you are certain that your symptoms are allergic you will not benefit much from doubling your dose. Instead, I suggest that you continue to take a 24-hour antihistamine once a day and go to the pharmacy to get a nasal corticosteroid such as Nasacort or FLONASE available over the counter. If you have had a prescription in the past, the pharmacist may be able to prescribe it under certain conditions.