How to Determine Allergies Causing Cold Sores. Cold sores are small, blister-like ulcers that occur in and around the mouth. Brought on by many triggers, such as stress and cold and flu; allergies may also bring cause a cold sore outbreak. If you are prone to cold sores, it may be time to determine whether or not an allergy is causing them.

Start with your toothpaste, as many oral hygiene products contain sodium laurel sulfate (SLS), which can trigger cold sores when allergies are present. Swap your regular toothpaste for a natural one for a few weeks and watch for changes.

Cut high gluten cereal grains from your diet for a few weeks to determine if your cold sores are the result of a gluten allergy. Major grains to eliminate include buckwheat, wheat, rye, barley and oats. If it seems that cutting gluten stops your cold sores, speak to a doctor or nutritionist about developing a new diet to fit your needs.

Eliminate dairy products from your diet for a few weeks. While rare, occasionally a person with lactose intolerance may suffer from cold sores as a reaction to the allergy.

Remove all processed foods from your diet for a few weeks, as a number of food additives, particularly cinnamonaldehyde and benzoic acid can trigger cold sores. Remember that these additives are not only present in foods, but also chewing gum. Read all labels carefully during the trial period.

Get a full allergy test from a doctor since a number of food items such as nuts, vinegar and soy could be the culprit.


Elimination of specific foods, when investigating food allergies, should last at least 4 weeks. At the end of the elimination period, sample that food and then wait a few days to see if a reaction occurs. Only eliminate one food item at a time when trying to determine allergies. The process of trial and error can be long and challenging; however, for those with chronic or reoccurring cold sores, it can make a huge difference.