3. Allergies
Many people associate allergies with symptoms such as sneezing, coughing, and possibly a rash. However, if you are allergic to certain types of foods, you may also develop a canker sore as a result of eating that particular food. A person may be allergic to many different types of foods. Some foods that may be more likely to cause a canker sore include chocolates, coffee, and any food that has a high amount of citruses, such as oranges and other fruits.
If you notice that you develop canker sores more often when you eat certain foods, it could be that you are slightly allergic to that particular food. Try cutting those foods out of your diet to see if the number of canker sores that you develop lessens. You may also want to be tested for different allergens if you find that you often develop canker sores.