If your canker sore has not healed in more than two weeks, you need to investigate further to find the reasons why. About 15% of canker sore sufferers have the more severe form called major aphthous stomatitis. These ulcers tend to be larger in size than the more common type classified as minor aphthous stomatitis. The general recommendation is for you to seek medical advice if your canker sores are not healed within two weeks so your doctor can perform a more thorough workup.

Sometimes all it takes is to get some simple blood tests to investigate the cause(s). Your doctor may order a test to determine levels of certain vitamins and minerals. If it is found that your levels are low, a supplementation may be all that is needed. If your blood tests show normal levels, your doctor may consider a biopsy of the lesion to make sure it is benign. 

Other Medical Conditions that Look Like Canker Sores

Oral thrush

Oral thrush presents as white patches on the tongue or side of the mouth. It is caused by a fungal growth on the tongue. It is usually caused by antibiotic use, certain medications that suppress your immune system, asthma medications such as inhaled steroids, or a weakened immune system. Oral thrush can be treated with an antifungal medicine. 

Gingivostomatitis

Painful ulcers inside the mouth caused by HSV-1 virus (the same virus that causes cold sores or fever blisters), or less commonly the coxsackievirus. Gingivostomatitis usually affects children under 5 years of age. If the oral lesion does not improve, your doctor may prescribe an antiviral medicine.

Leukoplakia

Leukoplakia is usually caused by physical trauma (ill-fitting dentures or braces), and smoking. Some people mistake these to be canker sores. The ulcer is harmless and usually not painful like canker sores. Sometimes, precancerous cells can look like leukoplakia. If you know that the white patches come out of nowhere, and are not caused by trauma to the mouth, follow them closely and seek medical advice as appropriate

Oral Lichen Planus

Oral lichen planus is a non-infectious ulcer that may look like canker sores. It is an autoimmune reaction where your body attacks its own oral mucous membrane. The reason is unclear but it is correlated with certain medications or viral illness. Oral lichen planus increases the risk of oral cancer, so seek medical advice so it can be closely monitored.

Oral cancer

Oral cancer lesions can initially look like canker sores, but they are usually not painful in the early stages. They tend to be raised, whereas a canker sore is usually flat. Most canker sores heal within 14 days. On the other hand, oral cancer does not heal without medical treatment. Note that these are generalizations, and there are always exceptions. Seek medical advice if your oral ulcer does not heal within two weeks. If oral cancer is detected early, survival rate is up to 90%.

Other Medical Conditions Associated with Recurrent Canker Sores

There are some underlying medical conditions that are may be associated with recurrent canker sores that usually take longer heal. For example, people who have celiac disease or gluten sensitivity tend to get recurrent canker sores because they cannot absorb important nutrients properly. There are also canker sores that result as a symptom of an autoimmune disease such as Crohn's or lupus.

Conclusion

Remember that for the majority of canker sores, there is nothing to worry about because they will go away and leave no lasting effects. It's highly unlikely that it is a more serious condition, but it is important to be vigilant when they don't heal or take too long to heal. If you suspect that your chronic canker sores are due to an underlying medical condition, contact your doctor for a complete workup.

Sandie Tran, Pharm.D.