Many of us tend to use the terms “cold sores” and “canker sores” interchangeably. After all, they’re both pesky, painful mouth sores, right? Turns out, there are more differences than similarities between the two. Here’s how to tell if you have a canker sore versus a cold sore.
What is a canker sore?
Canker sores, also called aphthous ulcers, show up as open sores on the inside of your mouth, usually on the inner parts of your cheeks or lips or on your tongue. You wouldn’t find them on the gingival [gum] tissue or the hard palate, although they can appear at the very base of your gums. Unlike cold sores, they aren’t contagious. No one knows exactly what causes or triggers canker sores. It could be a virus, allergy to food or medicine, stress, smoking, a nutritional deficiency like low vitamin B12, folic acid or iron, hormones (which may account for why twice as many women as men get canker sores) and spicy or acidic foods, like tomatoes and citrus fruit. Canker sores also tend to run in families and are more common in people who have dry mouths (which can be due to some medications). Canker sores may also be due to a physical injury. At times, I see them show up a few days after some traumatic event: contact sports, a frayed brush, a sharp potato chip, or even poorly fitting oral devices.
In most cases, you can let canker sores run their course. Most go away within a couple of weeks. In some cases, canker sores can be a sign that something more serious is going on, including celiac disease or another autoimmune condition. People who have recurrent canker sores should probably see a doctor who really understands these other disease processes. You can also try a canker sore toothpaste – basically a toothpaste without sodium lauryl sulfate (SLS – a harsh detergent found in many typical toothpaste) – to see if that may be contributing to your canker sores.
What is a cold sore?
Unlike canker sores, cold sores can appear outside your mouth, often on the corner of your lip. Also called fever blisters, they are in fact little blisters that tend to break quickly, leak fluid, then eventually scab over. You might feel a little tingling in the day or two before a cold sore appears. This is the best time to apply medication to shorten the duration of the cold sore.
There’s no mystery about what causes cold sores: It’s the herpes simplex virus 1 or HSV-1. Herpes viruses are extremely contagious and very common – more than half of people will have HSV-1 by the time they reach their twenties.
After the initial infection, HSV-1 travels up the nerve, staying out of sight until something triggers it. Then, it migrates back down the nerve to the mouth. Once it establishes itself, any time there’s trauma or any sort of transient lapse in immunity, the virus is going to manifest itself. Basically, any time your body isn’t functioning at full capacity, throwing its immune system out of whack, you are likely to end up with a cold sore.
Stress is a big trigger, along with sun exposure, fatigue and other infections (like a cold). If you know your triggers, you may be able to prevent an attack (for example, by reducing stress or putting zinc on your lips before going outside). Cold sores also typically show up in the same place every time you get one.
Most cold sores go away in their own time, usually seven to 10 days after they appear. The pain often reaches a peak in the first 24 hours. In the meantime, there’s little you can do except address the pain: Try icing the blisters or taking over-the-counter pain relievers.
Topical antiviral creams or ointments may lessen pain or quicken healing, but only if they’re applied at the very beginning of the outbreak or, even better, during the tingling phase.
For treatment of cold sores and canker sores, visit your dentist to see what treatments are best for you.