Sore throat is a common symptom of allergies. Many people will experience a painful, itchy, swollen throat while having an allergic reaction, though the connection between allergies and sore throat varies. The source of the reaction may be environmental irritants, such as pollen or mold; in these cases, the sore throat is often a byproduct of the nasal congestion associated with the attack. Food allergies can also provoke a response in the body that leads to a sore throat; this type of reaction is typically a direct result of the allergic reaction itself.
Allergies and sore throat are often connected due to the congestion that accompanies a reaction to environmental allergens. Many times these are seasonal allergies like hay fever, though other irritants such as animal dander, cigarette smoke, or pollution may have the same effect. People with these types of allergies typically experience nasal congestion, which in turn leads to the sinuses draining into the back of the throat. The constant presence of this post-nasal drip irritates and inflames the lining of the throat. As long as the nasal congestion persists, the patient will typically continue to have a sore throat; if left untreated, the chronic congestion may progress to infection, which can make the situation even worse.
Along with post-nasal drip, other effects of sinus congestion may arise from allergies and sore throat can be the result. If the person is unable to breathe through his or her nose, he or she may be forced to breathe through the mouth, particularly while sleeping. The inhalation of air this way can dry the throat, making it sore. Excess mucus may also lead to coughing, which may further aggravate the throat.
Food allergies and sore throat also often go together, though unlike with environmental agents, it is the allergic reaction itself that usually causes the pain directly. When a person eats a food to which he or she is allergic, antibodies develop in the body and attach to cells called mast cells. The next time the food is eaten, it interacts with the antibodies on the mast cells, which in turn stimulate the mast cells to emit substances such as histamine to attack the perceived threat. Since mast cells are common in the tissue of the throat, and the cells are exposed to food there when it is swallowed, a sore throat is often a result of this type of reaction.