An itchy throat can be the result of irritation in the upper airway, including your nose, mouth and throat. Often the clue to what’s causing the itch is in other symptoms.
Allergies
Allergies are one of the top reasons people experience throat irritation. When you’re exposed to allergens like pollen, dust mites, mold spores, or pet dander, your immune system may overreact and release natural chemicals called histamines. These histamines trigger inflammation and itchiness in your throat, nose, and eyes as well as other symptoms, like sneezing, a runny nose, watery eyes, and postnasal drip.
Even if you don’t have a full-blown immune response to an allergen, your body may still perceive it as foreign and treat it as something it needs to get rid of or fight against — and that could cause an itch or irritation leading to persistent throat clearing.