Whilst most people would associate a sore throat with a cold or flu and expect allergy symptoms to be more along the lines of a runny nose this is not always the case. It is not that uncommon for a sore throat to be yet another symptom of an allergy.
The biggest single cause of sore throat in allergies is postnasal drip. This is where an excess of mucus is produced in the nose and instead of (or as well as) causing a runny nose, the mucus drips down the back of the throat.
Now, the average person produces around a litre, or a quart, of mucus, snot, phlegm – call it what you like – every single day. This serves to keep your airways clean and moist, protecting them from infection. However, considerably more may be produced under certain circumstances, and this can lead to postnasal drip. Common causes include colds, the weather, irritants like tobacco smoke and nasal allergies.
So what does postnasal drip have to do with my sore throat? Well, mucus contains inflammatory components which means it can irritate the lining of your throat as it passes. In addition all the extra throat-clearing and coughing further serves to cause a sore throat.
How you treat your sore throat will depend on whether it is caused by a cold or allergy. Often an allergy will be accompanied by a certain degree of itchiness and the most effective treatment to stop a runny nose will be taking antihistamines. Decongestants can also offer some relief from postnasal drip and are effective with colds too.
Of course for longer term relief from a sore throat caused by allergies you will need to address the cause of your allergy and try to eliminate the allergen. This article on reducing dust mites has some useful tips which apply to other household allergies.