Most mouth sores heal on their own within one to three weeks, but the right care can cut down pain and speed things along. The approach depends on what type of sore you’re dealing with, how large it is, and whether anything is triggering repeat outbreaks. Here’s what actually works and what to watch for.
Identify What You’re Dealing With
The two most common mouth sores are canker sores and cold sores, and they require different treatment. Canker sores appear inside the mouth as a single round white or yellow sore with a red border. Their cause isn’t fully understood, but they can be triggered by injury, stress, smoking, or deficiencies in folic acid, iron, or vitamin B12. Cold sores, on the other hand, show up on the outside of the mouth around the lips as a cluster of small, fluid-filled blisters. They’re caused by herpes simplex virus type 1 (HSV-1) and are contagious.
This distinction matters because canker sores respond well to topical pain relief and home remedies, while cold sores often benefit from antiviral treatment. The rest of this article focuses primarily on canker sores and general mouth sores inside the mouth, since those are what most people mean when they search for healing tips.
How Long Healing Takes
Minor canker sores, the most common kind, are smaller than a pea (under one centimeter across). They typically heal within a few weeks and don’t leave scars. Major canker sores are larger than one centimeter, significantly more painful, and can take months to fully resolve. These often do leave scarring. If your sore is small and you’ve had it for less than two weeks, you’re almost certainly dealing with a minor one that will close up on its own.
Saltwater Rinses
A warm saltwater rinse is the simplest and most effective home treatment. Salt water promotes healing by encouraging the migration of cells that repair soft tissue and by helping regulate the wound repair process at a cellular level. The standard recipe is one teaspoon of salt dissolved in eight ounces of warm water. Swish gently for 30 seconds, then spit. If the sting is too much, drop to half a teaspoon of salt for the first day or two while the sore is at its most raw. Repeat a few times a day, especially after meals.
Over-the-Counter Pain Relief
Products containing 20% benzocaine, an oral anesthetic, are widely available and designed specifically for canker sores and minor mouth irritation. To get the best results, dry the affected area first with a clean tissue or cotton ball, then apply the medication with a cotton swab. Give it a few seconds to form a protective film coating over the sore. You can reapply up to four times a day. This won’t speed healing directly, but it makes eating and talking far more bearable while your body does the repair work.
Antiseptic rinses containing hydrogen peroxide (usually diluted to 1.5%) can also help keep the area clean and prevent secondary infection, which is one of the things that slows healing down.
Honey as a Topical Treatment
Applying a small amount of honey directly to a mouth sore has real evidence behind it. Research compiled by the UK’s National Institute for Health and Care Research found that honey reduced the onset of moderate to severe oral inflammation by 75% compared to usual care, with no significant increase in side effects like bacterial or fungal infection. That research focused on patients with mouth sores from cancer treatment, but the wound-healing and anti-inflammatory properties of honey apply broadly. Dab a small amount of raw honey onto the sore a few times a day. It stings briefly, then forms a soothing coating.
Prevent Repeat Outbreaks
Check Your Toothpaste
Sodium lauryl sulfate (SLS), a foaming agent found in most major toothpaste brands, is a known soft tissue irritant. It’s the same compound used in shampoos, soaps, and household cleaners. If you get canker sores frequently, switching to an SLS-free toothpaste is one of the easiest changes you can make. Several brands market themselves as SLS-free specifically for this reason.
Address Nutritional Gaps
Deficiencies in vitamin B12, iron, and folate are linked to recurrent mouth sores. In one study comparing people with repeat canker sores to healthy controls, over half of the canker sore group had low vitamin B12 levels, while none of the controls did. More importantly, 73% of patients with B12 deficiency who received B12 supplementation recovered completely, and 70% of patients with recurrent sores improved with nutritional replacement therapy overall.
If you’re getting canker sores more than a few times a year, it’s worth looking at your diet. Foods rich in B12 include meat, fish, eggs, and dairy (or fortified cereals if you’re plant-based). Folate comes from leafy greens, beans, and citrus. Iron is found in red meat, lentils, and spinach. A simple blood test can confirm whether a deficiency is driving your outbreaks.
Manage Common Triggers
Beyond SLS and nutrition, several everyday stressors make canker sores more likely: lack of sleep, acidic foods (citrus, tomatoes, vinegar-based dressings), physical trauma to the mouth from biting your cheek or aggressive brushing, and heavy plaque buildup. Keeping a consistent sleep schedule, moderating acidic foods when you feel a sore forming, and staying on top of dental hygiene all reduce flare-up frequency over time.
When a Mouth Sore Needs Attention
Most mouth sores are harmless, but a sore that doesn’t heal after three weeks is a red flag. Persistent, non-healing ulcers are one of the early warning signs of oral cancer, along with unexplained lumps, difficulty opening your mouth, or numbness in part of your lip or tongue. These signs don’t mean cancer is likely, but they do mean a professional should take a look. Distinguishing a potentially serious lesion from a benign one through visual inspection alone is unreliable even for clinicians, so a biopsy or further workup may be recommended.
Other reasons to get a mouth sore evaluated: it’s unusually large (bigger than a centimeter), it’s accompanied by a high fever, you’re getting sores so frequently they overlap, or the pain is severe enough to prevent eating or drinking.