Most canker sores heal on their own within two weeks, but you can speed up relief and reduce pain starting today with a few simple treatments. These small, shallow ulcers inside the mouth are not contagious and not related to cold sores (which appear on the lips). The key is treating them early, right when you first feel that tingling or spot of tenderness.
What You’re Dealing With
Canker sores, clinically called aphthous ulcers, show up on soft tissue inside your mouth: the inner cheeks, lips, gums, tongue, or soft palate. Most are minor aphthae, meaning they’re less than 1 cm across and relatively shallow. Pain typically improves within a few days, and the sore resolves completely in one to two weeks without any treatment.
Major aphthae are larger, deeper, and can take significantly longer to heal. These sometimes leave scars. A third type, herpetiform ulcers, appear as clusters of tiny sores. If your canker sore is unusually large, keeps coming back, or hasn’t healed after two weeks, that warrants a visit to your doctor or dentist to rule out other conditions.
Home Remedies That Actually Help
The simplest and most effective home treatment is a saltwater or baking soda rinse. Mix about half a teaspoon of salt (or baking soda) into a cup of warm water and swish for 30 seconds, then spit. This creates an alkaline environment in your mouth that reduces acid and irritation, helps prevent infection, and promotes healing. You can do this several times a day, especially after meals.
Applying a small amount of milk of magnesia directly to the sore with a cotton swab works on a similar principle, neutralizing acid right at the ulcer surface. Some people dab a paste of baking soda and water directly onto the sore for more targeted relief. It stings briefly but calms the area afterward.
Ice chips held against the sore can temporarily numb the pain. Avoiding acidic, spicy, or rough-textured foods while you have an active sore prevents the kind of repeated irritation that slows healing.
Over-the-Counter Treatments
Several OTC products can relieve pain and may shorten healing time, especially if you apply them as soon as the sore appears. The most common active ingredients to look for are:
- Benzocaine (found in Anbesol, Orabase, Zilactin-B): a topical numbing agent that dulls pain on contact
- Hydrogen peroxide rinses (such as Orajel Antiseptic Mouth Sore Rinse or Peroxyl): antiseptic rinses that clean the sore and reduce bacteria
These come as gels, pastes, creams, or liquids. Pastes and gels tend to stay on the sore longer than liquids, giving the active ingredient more contact time. For even better protection, adhesive canker sore patches form a physical barrier over the ulcer that shields it from food, drinks, and saliva for hours at a time. Patches stay in place through normal eating and drinking, delivering slow, sustained relief compared to sprays or rinses that wash away within minutes.
When OTC Options Aren’t Enough
If your canker sores are large, extremely painful, or keep recurring, a doctor or dentist can prescribe stronger options. Prescription-strength steroid pastes reduce inflammation directly at the sore. These are applied after meals and at bedtime using a cotton swab. You press a small amount onto the ulcer to form a smooth film rather than rubbing it in, which would make the paste crumbly and ineffective.
For severe or frequent outbreaks, your doctor may also check for underlying nutritional deficiencies. Low levels of vitamin B12, folate, and iron are all linked to recurrent mouth ulcers. A simple blood test can identify these, and correcting the deficiency through diet or supplements often reduces how frequently sores appear.
Preventing the Next One
One surprisingly common trigger is your toothpaste. Many toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that irritates oral tissue. A clinical study found four times fewer soft tissue lesions when participants used SLS-free toothpaste compared to one containing SLS. If you get canker sores regularly, switching to an SLS-free brand is one of the easiest changes you can make. Look for it on the ingredients list, or search for brands that specifically market themselves as SLS-free.
Other common triggers include biting the inside of your cheek, braces or ill-fitting dental appliances rubbing against tissue, stress, hormonal changes, and acidic foods like citrus fruits and tomatoes. Keeping a rough mental log of what preceded each outbreak can help you identify your personal triggers. Some people notice a pattern with certain foods, sleep deprivation, or stressful periods at work.
Canker Sore vs. Something More Serious
A typical canker sore is painful, round or oval, white or yellowish in the center with a red border, and heals within two weeks. If a mouth sore persists beyond two weeks, keeps growing, doesn’t hurt (painless sores can be more concerning than painful ones), or is accompanied by a high fever, difficulty swallowing, or unexplained weight loss, get it evaluated. Persistent mouth sores that don’t follow the normal healing pattern can sometimes signal other conditions, and a doctor may perform a biopsy, taking a tiny tissue sample to check for abnormalities.