How to Tell the Difference Between a Cold Sore and a Canker Sore
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There’s something growing on your lip — and it sure is unsightly, not to mention it kinda hurts. It looks like a cold sore — no, wait, a canker sore. How to tell the difference?
Cold sores and canker sores are not only common — millions of Americans experience both mouth pains every year — they are also commonly confused, says infectious disease expert Thomas Quinn, MD, professor of medicine at the Johns Hopkins University School of Medicine. But they’re actually quite different from each other, both in what they’re caused by, and how they’re treated. Here’s how to ID both.
Canker Sores
What they are: Canker sores, also called aphthous ulcers, are painful lesions that usually only pop up on the insides of your mouth, inside your lip, or on your tongue, Quinn tells Yahoo Health. They’re almost always small — about a quarter of an inch diameter, he estimates.
They’re signs of abnormal inflammation and look like little punched out spots with a whitish/yellowish skin, Arash Mostaghimi, MD, MPA, a dermatologist at Brigham and Women’s Hospital, tells Yahoo Health. You can have just one or multiple sores throughout the inside of your mouth. “The thing that characterizes them is that they are very painful and uncomfortable,” Quinn adds. “Sometimes, it hurts to talk and eat.”
Who gets them: Just about everybody has had a canker sore, says Quinn, but some people are prone to having them more frequently. Cankers tend to occur somewhat more frequently in women than men, as well as in younger people versus older people, he says. Plus, if Mom and Dad suffered, you may be more likely to as well, adds Mostaghimi.
Unfortunately, docs aren’t sure what causes these little ulcers, though there are some theories. They’ve been linked to everything from a disruption of microbial flora to vitamin deficiency, Quinn says. What researchers do know: Canker sores usually present during times of stress (when you’re likely not eating or sleeping well), says Quinn. It could also be that stress can cause changes in your mouth flora that lead to inflammation, Quinn says, but the science simply isn’t sound enough to say for sure.
And while you can cut the inside of your mouth by chewing something incorrectly, this usually leads to what docs call a “trauma ulcer,” not a canker sore, says Quinn. Canker sores, rather, appear to come “out of the blue.”
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Can you treat them? Over-the-counter topical treatments like Orabase and Kanka work to numb the sore, which can help ease the pain (and make it easier to eat). But these aren’t cures. “Canker sores are annoying but are usually benign [and] resolve themselves in under two weeks,” says Mostaghimi.
Do you need to worry? If you have multiple sores that aren’t going away after 10 days — and they turn more yellow or are giving you bad breath, see a doctor. “There are diseases that can mimic canker sores that are more serious — like leukoplakia, which is categorized by patches on the tongue or inside of the mouth,” says Quinn. With canker sores that aren’t changing or subsiding, docs worry about autoimmune diseases or pre-cancerous lesions, too, so it’s better to be safe than sorry.
Cold Sores
What they are: Cold sores, also called fever blisters, tend to start out as a blister and turn into an ulcer (a canker sore, on the other hand, is always an ulcer). Unlike cankers, they also usually occur on the outside of the lips or on the vermilion border — where your lips meet your skin, says Mostaghimi. Depending on the severity, you could see anything from a small blister to fluid-filled lesions that might be tingly, itchy, oozing, or crusty. Expect a cold sore to hang around for about five to 10 days.
And yes, cold sores can occur in your mouth, says Quinn — it’s just far more rare.
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Who gets them: Unlike canker sores, doctors do know what causes cold sores: herpes simplex virus type I. “Sometimes people don’t want to say, ‘I have herpes’, so they say, ‘I get cold sores,’” Quinn says. “The terms are mostly interchangeable.” Even more: Quinn estimates that about 80 percent of the U.S. population has herpes — and just may not know it.
For the majority of Americans who are unknowingly infected, the virus lays dormant, explains Mostaghimi. It’s like your body is constantly fighting the virus and winning, so you never know it’s there. But for about a third of people infected, every now and then, the virus beats your immune system and a cold sore may pop up, he says. Stress, changes in hormones, immunosuppression, or having a fever can all bring about recurrences, says Quinn.
Can you treat them? If you’re plagued by frequent cold sores, a prescription antiviral drug can help with the pain. It can also shorten the duration of outbreaks, says Quinn.
Do you need to worry? Call your doc if you think you see a cold sore for the first time. While they’re very common, there is a swab test for herpes. And it’s worth knowing if you have it so that you can control spreading the virus and be aware of outbreaks.
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