Canker sores (Aphthous ulcers): Symptoms, causes & treatment

What are canker sores?

Canker sores, also called aphthous ulcers, are those small, round or oval spots that form inside your mouth - usually on the tongue, inner lips, cheeks, or even near your gums. They're white or yellow in the center with a red border around them, and while they're harmless, they can be seriously painful for their size.

The important thing to know is that canker sores aren't contagious. You can't catch them from kissing, sharing utensils, or drinking from the same cup. They're just your body's reaction to something - stress, irritation, or even a minor injury inside your mouth.

How long do canker sores last? Well, most canker sores heal up on their own within 7 to 14 days, but that doesn't make them any less annoying. The pain can make eating, brushing, and even smiling feel like a challenge.

Canker sores - Aphthous ulcer symptoms

You'll know it when you've got one. That sharp sting when you eat something salty or brush your teeth a little too hard - classic canker sore pain.

Here's what you'll usually notice:

They might look tiny, but if you've ever had one, you know - that small sore can make your whole mouth feel sore.

What causes canker sores?

There's no one single reason why you get a canker sore. It's usually your body's way of saying something's off.

Here are some of the most common canker sore causes:

Basically, if your mouth's irritated, your body's stressed, or your diet's missing key nutrients, a canker sore could be just waiting to pop up.

Canker sores vs. Cold sores

People often mix these up - and it's easy to understand why. Both hurt, both show up around your mouth, and both can make eating or brushing a real struggle. But they're actually very different.

So, if you're wondering whether you can catch a canker sore from someone with braces or not, the answer is no. Canker sores are not contagious and have nothing to do with viral infections.

If you wear braces, though, you're more likely to get them. The brackets and wires can rub against your cheeks or gums, causing tiny cuts that can turn into ulcers. Cold sores, on the other hand, develop outside the mouth and can spread through direct contact like kissing or sharing utensils.

The quick way to tell the difference?

Tired of mouth sores from braces?

Caspersmile clear aligners are smooth, removable, and gentle on your mouth - no metal edges, no irritation, no ulcers.

Explore our aligners

Treatment & home remedies

Most of the time, canker sores heal on their own. But if you want to ease the pain and speed things up, here are some options for canker sores treatment:

Over-the-counter options:

Canker sore remedy:

Pain relief:

You can take ibuprofen or paracetamol for a day or two if the pain is strong - just make sure you're not overdoing it.

When to see a dentist

Most sores fade away in 7 to 14 days, but sometimes they stick around longer or come back too often.

You should see a dentist or doctor if:

Sometimes recurring ulcers can be a sign of something else going on - and a quick check-up can give you peace of mind.

How to prevent future canker sores

You can't always stop them from showing up, but you can definitely reduce how often they appear.

Here's what helps:

And if you're someone who gets ulcers from braces or dental friction - switching to clear aligners might be worth considering. They're smooth, removable, and gentle on soft tissues.

Bottom Line

Canker sores might be small, but anyone who's had one knows just how much they can hurt. The good news? They're temporary - and with the right care, they heal faster than you think.

Keeping your mouth clean, calm, and free from irritation is key. Avoid spicy or acidic foods, stay hydrated, and give your mouth a little extra TLC while it recovers.

If you're getting canker sores often, don't brush it off - it could be your body's way of saying something's off, like stress, diet, or friction from braces or dental appliances.

Don't let mouth sores keep slowing you down. Protect your oral health and see how clear aligners can help you maintain a smoother, healthier, and more comfortable smile - no sharp brackets, no irritation.

Frequently asked questions

How long do canker sores last? +

Most canker sores heal on their own within 7 to 14 days. If yours lasts longer or keeps coming back, it’s worth checking with a dentist.

Can braces cause canker sores? +

Yes - braces can trigger canker sores. The metal brackets or wires can rub against your cheeks or gums, causing irritation that turns into ulcers. Using orthodontic wax and keeping your mouth clean can help prevent them.

Are canker sores contagious? +

No, canker sores are not contagious. You can’t catch them from kissing, sharing utensils, or close contact - they’re caused by irritation, stress, or other internal factors.

What helps canker sores heal faster? +

Rinsing with salt water or baking soda, avoiding spicy or acidic foods, and using a gentle mouthwash can help speed up healing. For pain, you can use over-the-counter gels or pain relievers.

When should I see a dentist about a canker sore? +

If your sore lasts longer than two weeks, is unusually large, or comes with fever or swollen glands, it’s time to see a dentist. Frequent sores can also be a sign of an underlying issue that needs attention.