Most canker sores heal on their own within 7 to 14 days, but the right combination of home care and over-the-counter products can cut pain significantly and help the sore close faster. There’s no instant cure, but you can speed things along and make eating and talking far more comfortable in the meantime.
What You’re Dealing With
Canker sores (aphthous ulcers) are small, shallow wounds on the soft tissue inside your mouth: the inner cheeks, lips, gums, tongue, or soft palate. They’re not cold sores, which appear on the outside of the lips and are caused by a virus. Canker sores aren’t contagious at all.
About 75% to 85% of canker sores are the minor type, less than 1 cm across, and they heal without scarring in one to two weeks. A smaller percentage are major aphthae, larger than 1 cm, which can linger up to six weeks and sometimes leave scars. A third type, called herpetiform, appears as clusters of dozens of tiny sores that look alarming but typically heal within two weeks.
Home Rinses That Actually Help
A saltwater or baking soda rinse is the simplest first step, and it works. The rinse reduces bacteria around the ulcer and creates an environment that supports healing. Memorial Sloan Kettering Cancer Center recommends these specific ratios:
- Salt rinse: 1 teaspoon of salt in 1 quart (4 cups) of water
- Baking soda rinse: 1 teaspoon of baking soda in 1 quart of water
- Combination rinse: 1 teaspoon of salt plus 1 teaspoon of baking soda in 1 quart of water
Swish gently for 30 seconds and spit. Repeat every four to six hours, or more often if the pain is bothering you. Baking soda is particularly helpful because it neutralizes acid in the mouth, which is one of the main things irritating an open sore. You can make a paste with a small amount of baking soda and water and dab it directly on the ulcer for more concentrated relief.
Over-the-Counter Products Worth Trying
Topical numbing gels and pastes containing benzocaine are the most widely available option at pharmacies. You apply them directly to the sore, and they create a temporary numbing effect that makes eating and drinking less painful. Look for products specifically labeled for mouth sores, since the formulation is designed to stick to wet tissue.
Protective pastes and patches are another category. These form a barrier over the sore, shielding it from food, drinks, and your teeth. The barrier reduces irritation throughout the day and can help the sore heal faster simply by preventing repeated trauma to the area. Some products combine a numbing agent with this protective coating.
Hydrogen peroxide, diluted to half strength with water, can also be dabbed on a canker sore with a cotton swab to help keep it clean. Don’t swallow it, and don’t use full-strength peroxide, which can irritate healthy tissue around the sore.
When Prescription Treatment Makes Sense
If you get canker sores frequently, or if you have several at the same time, a prescription mouth rinse containing a steroid or a numbing agent can reduce pain and inflammation more effectively than what’s available over the counter. These rinses are swished around the mouth and coat multiple sores at once.
For stubborn individual sores, a chemical cautery treatment can be applied at a dental or medical office. One product chemically seals the sore and may reduce healing time to about a week. Silver nitrate is another cautery option that won’t speed healing but can provide significant pain relief by deadening the nerve endings on the ulcer’s surface.
Foods to Avoid While Healing
What you eat matters more than you might expect when you have an open sore in your mouth. Acidic foods are the biggest offenders: citrus fruits, tomatoes, tomato sauce, strawberries, coffee, and soda all increase the acid level in your mouth and directly irritate the ulcer. Even diet soda is just as acidic as regular. Spicy foods containing hot peppers will cause obvious, immediate pain on contact.
Physically rough or sharp foods are the other major category to avoid. Chips, pretzels, crusty bread, and nuts can scrape the sore and re-open healing tissue. Stick to soft, cool, bland foods while the sore is at its worst. Yogurt, smoothies, scrambled eggs, mashed potatoes, and oatmeal are all safe choices that won’t set you back.
Why You Keep Getting Them
If canker sores are a recurring problem for you, there are several known triggers worth investigating.
Stress is one of the most common. When you’re under sustained emotional pressure, your body releases cortisol through a chain reaction involving the brain and adrenal glands. That cortisol surge alters your immune system, affecting the T cells, B cells, and other immune components that protect your oral tissue. The result is that your mouth’s lining becomes more vulnerable to breaking down into ulcers. This is why canker sores often show up during exam weeks, work deadlines, or emotionally difficult periods.
Nutritional deficiencies are another well-established cause. Low levels of iron, vitamin B12, folic acid, and zinc are all linked to recurrent canker sores. If you get sores frequently and can’t identify another trigger, it’s worth having your levels checked through a simple blood test. Correcting a deficiency sometimes resolves the problem entirely.
Your toothpaste may also play a role. Sodium lauryl sulfate (SLS) is a foaming agent in most toothpastes, and it’s a known irritant to oral tissue. Clinical research has specifically investigated whether switching to an SLS-free toothpaste reduces canker sore frequency, and many dentists recommend the switch for people who get frequent outbreaks. SLS-free toothpastes are available at most drugstores, often labeled as “gentle” or “sensitive” formulas.
Minor physical trauma is another trigger: biting the inside of your cheek, aggressive brushing, poorly fitting dental appliances, or even sharp edges on a broken tooth can all set off a canker sore in someone who’s prone to them.
Signs a Sore Needs Professional Attention
A canker sore that lasts longer than three weeks needs to be evaluated by a dentist or doctor. The same applies if the sore is unusually large, if it’s positioned near the back of your throat, or if it looks different from canker sores you’ve had before. Persistent or unusual mouth ulcers can occasionally signal other conditions that need to be ruled out. High fevers accompanying mouth sores, or sores that make it impossible to drink fluids, also warrant a prompt visit.