How to Get Rid of Canker Sores (What Helps, What Doesn’t, and When to See a Doctor)
Canker sores usually heal in about two weeks. Here's what eases the pain, what to avoid, how they differ from cold sores, and when to see a doctor.
In this guide
You can’t make a canker sore vanish overnight, but you can make it hurt a lot less while it heals. Most go away by themselves in about two weeks, and the worst of the pain is usually in the first few days. The trick is to avoid what irritates it and to use gentle care that takes the edge off.
Here’s what actually helps, what to skip, how to tell a canker sore from a cold sore, and when it’s time to get it checked.
What is a canker sore?
A canker sore (also called an aphthous ulcer) is a small, painful sore that shows up inside your mouth: on the inside of your cheeks or lips, on your tongue or on your gums. KidsHealth says it looks like a round open sore with a white or yellowish coating and a red border, and most are about 1/4 inch (6 millimeters) across, about the size of a kernel of corn.
They’re annoying, but they’re common, and they are not contagious. You can’t give one to someone by kissing or share one by drinking from the same bottle. KidsHealth also says teens and people in their early 20s get them most often, and that women are twice as likely as men to get them.
What causes canker sores?
Doctors don’t know the exact cause. Both KidsHealth and Cleveland Clinic list some things that can set one off:
- A small injury inside your mouth, like biting your cheek, brushing too hard, or a dental appliance that doesn’t fit well.
- Stress. Both sources list it as a possible trigger.
- Hormone changes around your period. Cleveland Clinic lists this as a common trigger.
- Toothpaste or mouthwash with sodium lauryl sulfate (SLS). Both sources mention this ingredient.
- Certain foods, especially spicy, salty or acidic ones, or something you’re allergic to.
- Low levels of folic acid, vitamin B12 or iron. KidsHealth says people whose diets are low in these seem to get canker sores more often.
Some people just get them more than others, and it can run in families.
How to get rid of a canker sore: what helps
There’s no instant cure, but these things ease the pain and let the sore heal without being bothered.
1. Protect it and leave it alone
Don’t poke it with your tongue, and don’t try to scrape or pop it. Brush with a soft-bristle toothbrush, and Cleveland Clinic also suggests waxed floss so you don’t scratch the area. It heals faster when it isn’t getting hurt again every few hours.
2. Eat and drink around it
Skip the foods KidsHealth says can sting: rough, crunchy foods like potato chips and nuts, and salty, spicy or acidic foods such as lemons and tomatoes. Go with soft, mild, cool foods for a few days: yogurt, mashed potatoes, oatmeal, smoothies (no citrus), scrambled eggs. MedlinePlus (from the National Library of Medicine) also suggests avoiding hot, spicy foods while you have one.
3. Rinse your mouth gently
Cleveland Clinic lists rinsing with salt water or a mild mouthwash as home care, and says an alcohol-free over-the-counter rinse is an option. Stay away from harsh, alcohol-heavy mouthwash. It can sting like crazy on an open sore.
4. Use an over-the-counter numbing gel or pain reliever
Cleveland Clinic says an over-the-counter topical anesthetic with benzocaine can ease the pain, and KidsHealth says pain relievers like ibuprofen or acetaminophen can help. Follow the directions on the package, and ask a parent, school nurse or pharmacist if you’re not sure what’s right for you.
If you use a gel or paste, KidsHealth suggests drying the area first, putting it on with a cotton swab, and then not eating or drinking for at least 30 minutes so it doesn’t get washed away.
5. Switch your toothpaste if it keeps happening
If you get sores often, try a toothpaste without SLS. Cleveland Clinic and KidsHealth both mention it as a possible trigger. It’s an easy, cheap thing to test. Give it a few weeks, since one sore either way doesn’t prove anything.
6. Take stress down a notch
Stress is a possible trigger, so it helps to deal with it before it piles up. Try some of these coping skills for hard days. Getting enough rest also helps you handle stress, so it’s worth a look at how to sleep better.
What not to do
- Don’t pick, pop or scrape it. It will hurt more and take longer to heal.
- Don’t brush hard around it. A soft brush is enough.
- Don’t keep eating what stings. Salty chips, hot sauce and citrus are not worth it this week.
- Don’t try random TikTok remedies like putting strong chemicals, crushed pills or undiluted anything on your mouth. If it’s not something the sources above recommend, check with a doctor, dentist or pharmacist first.
- Don’t assume it’s a cold sore and treat it like one. They’re different problems (see below).
Canker sore vs. cold sore: how to tell the difference
People mix these up all the time, and it matters because one is contagious and the other isn’t.
| Canker sore | Cold sore | |
|---|---|---|
| Where | Inside your mouth (cheeks, lips, tongue, gums) | On or around your lips and nose |
| What it looks like | Round open sore, white or yellow with a red border | Small, painful blisters |
| Cause | Exact cause unknown | The herpes simplex virus (HSV-1) |
| Contagious? | No | Yes |
| How long | About two weeks | Usually 1 to 2 weeks |
Sources: KidsHealth on canker sores and KidsHealth on cold sores.
If you have a cold sore, it spreads easily through close contact like kissing, and by sharing things like utensils or towels. KidsHealth says to wash your hands often and not share drinks or utensils until it’s healed. If you have a canker sore, you don’t need to worry about spreading it.
When to see a doctor or dentist
Most canker sores are a nuisance, not a medical problem. But get it looked at if:
- it lasts longer than two weeks (KidsHealth and Cleveland Clinic both say so)
- the pain is so bad that you can’t eat or drink normally
- you get new sores more than two or three times a year
- the sore is larger than about 1 centimeter, or you also feel sick with flu-like symptoms (Cleveland Clinic)
A doctor or dentist can check what’s going on and, if needed, prescribe a topical medicine or a special mouthwash. KidsHealth says that if sores are frequent or severe, a doctor may also check for things like nutrition problems, immune system issues or allergies.
Not sure how to set up the visit? Here’s how to make a doctor’s appointment if you’ve never done it yourself. And if your sore is near a braces bracket or a retainer wire that keeps rubbing, tell your orthodontist.
