Most mouth sores heal on their own within 10 to 14 days, but you can speed up recovery and cut the pain significantly with a few simple treatments. The right approach depends on what type of sore you’re dealing with, so it helps to identify that first.
Figure Out What Kind of Sore You Have
The two most common mouth sores are canker sores and cold sores, and they look and behave differently. Canker sores (aphthous ulcers) appear inside the mouth on the cheeks, lips, tongue, or gums. They’re round, white or yellow in the center, and ringed with red. They are not contagious. Cold sores (fever blisters), on the other hand, show up on the outside of the mouth, typically along the border of the lips. They start as clusters of small fluid-filled blisters rather than open ulcers, and they’re caused by the herpes simplex virus, which means they are contagious.
This distinction matters because the treatments are different. The advice below focuses primarily on canker sores and general mouth ulcers, since those are what most people mean when they search for help with a sore inside their mouth. Cold sores typically need an antiviral treatment, which is a separate path.
Home Remedies That Actually Help
A saltwater or baking soda rinse is the simplest and most effective first step. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish a mouthful around the sore for 30 seconds, then spit. You can repeat this several times a day. The solution reduces bacteria, lowers acidity in your mouth, and helps the tissue heal faster. St. Jude Children’s Research Hospital uses this exact formula for patients prone to mouth sores.
A few other things that help while you wait for healing:
- Ice chips or cold water: Holding something cold against the sore temporarily numbs the area and reduces swelling.
- Avoid irritating foods: Acidic foods like citrus and tomatoes, along with spicy or crunchy foods, will aggravate the sore and slow healing.
- Use a soft toothbrush: Brushing too aggressively near the sore can reopen it or make it worse.
Over-the-Counter Pain Relief
If the sore is painful enough to interfere with eating or talking, a topical numbing product containing benzocaine can help. It’s available without a prescription as a gel, paste, spray, ointment, or lozenge. Apply the gel or paste directly to the sore up to four times a day. If you’re using lozenges, dissolve one slowly in your mouth every two hours as needed. Benzocaine works by numbing the nerve endings at the surface, so relief is fast but temporary.
You can also find OTC products that form a protective film over the ulcer, shielding it from food and saliva. These barrier-style treatments reduce pain by keeping the raw tissue covered and can help it heal a bit faster.
When a Sore Needs Prescription Treatment
Minor canker sores, the kind most people get, heal within 10 to 14 days without scarring. Major aphthous ulcers, which are larger and deeper, can last weeks to months and may leave scars. If your sore falls into that second category, or if OTC treatments aren’t helping, a dentist or doctor can prescribe a steroid dental paste. These pastes reduce inflammation directly at the sore. You apply a small amount after meals and at bedtime, pressing it onto the ulcer with a cotton swab to form a smooth film. Don’t rub it in, as the paste will crumble if you do.
For widespread or especially severe outbreaks, a prescription steroid mouth rinse is another option. These work the same way but cover a larger area.
Nutrient Deficiencies and Recurring Sores
If you get canker sores repeatedly, a nutritional deficiency may be the underlying cause. In one study of patients with recurrent oral ulcers, over 50% were deficient in vitamin B12, compared to none in the control group. When those B12-deficient patients received supplementation, 73% recovered completely. Iron deficiency and low folate levels have also been linked to recurring mouth sores, though the connection is strongest with B12.
If you’re getting sores more than a few times a year, it’s worth asking your doctor to check your B12, iron, and folate levels with a simple blood test. Correcting the deficiency, whether through diet or supplements, can dramatically reduce how often sores come back.
Switch Your Toothpaste to Prevent New Sores
Many common toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that can irritate the lining of your mouth and trigger canker sores. A systematic review of clinical studies found that switching to an SLS-free toothpaste significantly reduced the number of ulcers. In one trial, participants went from an average of about 14 ulcers over three months with SLS toothpaste down to about 5 ulcers after switching to an SLS-free version.
SLS-free toothpastes are widely available at drugstores and grocery stores. Check the ingredients list on the back of the tube. If you get canker sores regularly and haven’t tried this switch, it’s one of the easiest and most evidence-backed changes you can make.
Signs a Mouth Sore Needs Medical Attention
Most mouth sores are harmless and temporary. But a sore that doesn’t heal after two weeks deserves a professional evaluation. Oral cancer can present as a mouth sore that persists, a white or reddish patch on the inside of your mouth, a lump or growth, unexplained mouth pain, ear pain, loose teeth, or difficulty swallowing and chewing. Any of these symptoms lasting beyond two weeks should prompt a visit to your doctor or dentist, who can physically examine the area and, if anything looks unusual, take a small tissue sample to test.
Also see a professional if you develop sores that are unusually large (bigger than about a centimeter), sores that keep coming back in clusters, sores accompanied by a high fever, or pain so severe that you can’t drink fluids. These patterns suggest something beyond a standard canker sore.