5 Surprising Causes of Canker Sores (and Proven Ways to Prevent Them)


Canker Sores

Are you tired of dealing with the pain and discomfort of recurring canker sores? As a dental professional with over a decade of experience, I’ve seen firsthand how these pesky mouth ulcers can disrupt daily life for the 1 in 5 people who regularly get them. Canker sores can make eating, drinking, and even talking a real challenge. But here’s the good news: by understanding the top causes of canker sores and implementing proven prevention and treatment strategies, you can dramatically reduce the frequency and severity of outbreaks. In fact, many of my patients have found lasting relief by following the tips I’ll be sharing with you today. So let’s dive in and explore the 5 most common reasons people get canker sores – some of them may surprise you!

Causes of Canker Sores

1. Nutritional Deficiencies

Did you know that what you eat (or don’t eat) can have a big impact on your risk of developing canker sores? Studies have shown that deficiencies in key nutrients like vitamin B12, folate, iron, and zinc are linked to a higher incidence of these painful ulcers. This is especially common in teens and young adults who may have poor diets lacking in fruits and vegetables.

So what’s the connection? These nutrients play important roles in maintaining the health of the mucous membranes that line your mouth. When levels run low, the tissue becomes more vulnerable to damage and inflammation. The good news is that upping your intake of nutrient-rich foods like leafy greens, lean proteins, and whole grains can help shore up these defenses. If you suspect you may be deficient, talk to your doctor about whether supplements could be beneficial. Just remember, a well-balanced diet is always the best foundation for preventing canker sores and supporting overall health.

2. Mouth Injuries and Irritations

Ouch! Even minor damage to the delicate tissues inside your mouth can trigger the formation of a canker sore. Common culprits include accidentally biting your cheek or tongue, sports-related injuries, overly vigorous brushing, and irritation from dental work. Believe it or not, even your toothpaste could be to blame – certain brands that contain sodium lauryl sulfate (SLS) have been shown to irritate the mouth and increase canker sore risk in some people.

Another frequent cause I see in my practice is rubbing or friction from ill-fitting dentures or braces. The constant pressure and abrasion can damage the soft tissues over time, leading to sore development. If you wear oral appliances, it’s so important to have them properly fitted and adjusted regularly to minimize this risk. And if you do notice any discomfort or sores developing, give your dentist a call right away so they can help troubleshoot the issue before it worsens.

3. Food Sensitivities

That spicy burrito or zesty lemonade might taste amazing going down, but for some people, certain foods can spell trouble when it comes to canker sores. Acidic fruits and veggies like oranges, lemons, tomatoes and strawberries are common triggers, as are spicy dishes, chocolate, coffee, and other known food allergens.

So how do you figure out which foods might be causing issues for you? One helpful strategy is to keep a food diary, jotting down what you eat and drink each day along with any canker sore symptoms that develop. Over time, you may start to see patterns emerge – for example, maybe you always seem to get a sore after eating pineapple or drinking orange juice. Armed with this knowledge, you can start steering clear of your personal trigger foods and see if your outbreaks subside.

Of course, it’s not always easy to avoid beloved foods, even if they don’t seem to agree with you. If cutting out acidic or spicy items feels too restrictive, you can also try making a point to rinse your mouth with water after consuming them. This can help neutralize any irritating compounds and reduce the contact time with your vulnerable oral tissues.

4. Genetics and Family History

Sometimes, canker sores seem to run in families – and research suggests there may indeed be a genetic component at play. Studies have shown that people with a parent or sibling who gets frequent canker sores are more likely to experience them as well. Certain inherited gene variants related to inflammatory response have also been linked to a higher risk of these painful ulcers.

While you can’t change the genes you were born with, being aware of your family history can help you and your healthcare providers take a more proactive approach to prevention. If you know canker sores are common in your family tree, it’s extra important to prioritize good oral hygiene, stress management, and a healthy diet to lower your chances of developing them. And if you do start getting frequent outbreaks, don’t hesitate to talk to your dentist or doctor – they can work with you to identify triggers and find the best treatment plan for your individual needs.

5. Stress and Hormonal Factors

Have you ever noticed that canker sores seem to crop up during times of high stress or anxiety? You’re not alone – many people report getting these painful ulcers more often when they’re feeling overwhelmed or emotionally strained. While experts aren’t entirely sure why stress seems to trigger sores, it’s thought that it may impair immune function and increase inflammation throughout the body, making the delicate tissues in your mouth more prone to damage.

Hormonal shifts, particularly those related to the menstrual cycle, are another common canker sore trigger for some women. Just like with stress, fluctuating hormone levels are believed to influence immune response and inflammatory processes in ways that can make sores more likely to develop.

So what can you do about it? While you may not be able to eliminate stress from your life entirely, prioritizing self-care and stress management techniques can go a long way in reducing your canker sore risk. Things like regular exercise, meditation, deep breathing exercises, and getting enough sleep can all help keep stress levels in check. If you suspect hormonal changes could be a trigger for you, talk to your gynecologist or primary care doctor – they may be able to recommend strategies or treatments to help balance things out.

Other Potential Causes

While the factors we’ve covered so far are some of the most common reasons people develop canker sores, they’re not the only ones. Certain underlying health conditions like celiac disease, inflammatory bowel disease (IBD), HIV/AIDS and others can also increase the risk of these painful ulcers. Some medications, such as non-steroidal anti-inflammatory drugs (NSAIDs) and beta-blockers, have also been linked to canker sores in certain people.

Lifestyle factors like smoking can also play a role. The chemicals in cigarettes can irritate the delicate tissues in your mouth, making them more vulnerable to damage and inflammation. Plus, smoking is known to weaken the immune system over time, which could further increase the risk of developing sores.

If you have frequent or severe canker sores and can’t seem to pinpoint the cause, it’s worth talking to your doctor to rule out any underlying health issues that could be contributing. They can also review your medications and lifestyle habits to see if any changes might be warranted.

Canker Sore Treatments and Remedies

While most canker sores will heal on their own within 1-2 weeks, there are steps you can take to ease discomfort and speed up the healing process in the meantime. Over-the-counter and prescription pastes, gels, rinses and other medications can help numb pain and protect the sore from further irritation. Your dentist or doctor can recommend the best option for your specific needs.

There are also several home remedies that can provide relief and promote healing. Rinsing your mouth with warm salt water or baking soda mixed with water a few times a day can help soothe inflammation and keep the area clean. Dabbing a small amount of milk of magnesia directly onto the sore can also be effective thanks to its antacid properties. Sucking on ice chips or applying a cold compress to the outside of your cheek may numb the pain temporarily.

While you have an active sore, it’s best to avoid any foods that seem to irritate it further. Spicy, acidic, and abrasive items are common culprits, so stick to softer, blander fare until things heal. And of course, always maintain good oral hygiene by gently brushing twice a day and flossing regularly to keep your whole mouth healthy.

When to See a Doctor

While most canker sores are harmless and will clear up on their own, there are times when it’s important to seek medical attention. If you have a sore that is extremely painful, very large, or doesn’t start improving within a couple of weeks, it’s worth getting checked out. Sores that are spreading outside the mouth or accompanied by other symptoms like fever, fatigue, or diarrhea could indicate a more serious issue and should be evaluated promptly.

In some cases, your doctor or dentist may recommend tests to rule out underlying conditions like celiac disease, IBD, or a vitamin deficiency that could be contributing to your sores. They can also discuss prescription treatments that may be more effective than over-the-counter remedies for severe or recurrent cases.


Canker sores may be small, but they can certainly cause a big disruption to your daily life. While the exact cause isn’t always clear, factors like nutritional deficiencies, mouth irritation, food sensitivities, genetics, and stress are some of the most common triggers. The good news is that by identifying your personal risk factors and taking steps to prevent and treat outbreaks, you can dramatically reduce the impact of these pesky ulcers.

Simple strategies like eating a balanced diet, avoiding trigger foods, practicing good oral hygiene and stress management techniques can go a long way in keeping sores at bay. And if you do develop a canker sore, over-the-counter remedies and home treatments can help ease discomfort and speed healing.

Remember, if frequent or severe canker sores are impacting your quality of life, don’t hesitate to talk to your doctor or dentist. They can work with you to identify underlying causes, recommend effective treatments, and develop a plan to keep your mouth healthy and pain-free. With a little knowledge and proactive care, you can say goodbye to canker sores and hello to a happier, healthier smile.