Most mouth blisters heal on their own within 10 to 14 days, but you can speed up the process and reduce pain with a few simple treatments at home. The right approach depends on what type of blister you’re dealing with, since canker sores, cold sores, and other oral lesions each respond to different remedies.
Figure Out What You’re Dealing With
The two most common types of mouth blisters are canker sores and cold sores, and they require different treatment.
Canker sores appear inside the mouth, usually on the inner cheeks, lips, or tongue. They look like a single round white or yellow sore with a red border. They’re not contagious, and their exact cause isn’t fully understood, though stress, mouth injuries, smoking, and deficiencies in iron, folic acid, or vitamin B12 can trigger them. Canker sores tend to be painful, especially early on, and the pain decreases as they heal.
Cold sores show up on the outside of the mouth, around the lips. They appear as a cluster of small, fluid-filled blisters caused by the herpes simplex virus (usually HSV-1). They’re contagious. You’ll often feel a burning or tingling sensation before they appear, sometimes along with fatigue, fever, or swollen lymph nodes.
If your blister is inside the mouth and flat, it’s likely a canker sore. If it’s a cluster of fluid-filled bumps near the lip line, it’s probably a cold sore. This distinction matters because cold sores respond to antiviral treatments, while canker sores do not.
Home Remedies That Actually Help
A saltwater rinse is the simplest and most effective home treatment. 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 about 30 seconds, then spit it out. Do this several times a day, especially after meals. The salt helps draw out fluid and reduce swelling, while the baking soda neutralizes acids in your mouth that can irritate the sore.
You can also apply a small amount of milk of magnesia directly onto the sore with a cotton swab. Placing a damp tea bag against the blister for a few minutes may ease discomfort as well, since tea contains tannins with mild astringent properties. Ice or cold water held against the sore can temporarily numb pain.
Over-the-Counter Treatments
Numbing gels and pastes containing benzocaine are widely available and provide temporary pain relief. You’ll find this ingredient in products like Orajel and Anbesol. Apply a small amount directly to the sore before eating or whenever pain flares up. These won’t speed healing, but they make eating and talking much more comfortable.
For cold sores specifically, OTC antiviral creams can shorten the outbreak by a day or two if you apply them at the first sign of tingling, before blisters fully form. Protective patches that cover the sore can also prevent irritation and keep you from touching it.
Antiseptic mouth rinses containing hydrogen peroxide (diluted) can help keep the area clean and prevent a secondary bacterial infection from slowing healing.
When You Need a Prescription
If you get frequent or severe canker sores, a dentist or doctor can prescribe a steroid-based mouth rinse. These rinses reduce inflammation and pain more aggressively than anything available over the counter. You swish the solution in your mouth for about a minute after meals and before bed, then spit it out. They’re typically used for a short course until the sore resolves.
For recurring cold sores, prescription antiviral pills work faster and more effectively than topical creams. Starting them within the first 24 hours of symptoms makes the biggest difference.
Foods to Avoid While Healing
What you eat can either help or significantly delay healing. While you have an active sore, steer clear of these categories:
- Acidic fruits and sauces: Oranges, lemons, grapefruits, tomatoes, and vinegar-heavy dressings sting on contact and can slow the healing of open tissue.
- Spicy foods: Chili peppers and hot sauces create a lingering burn on raw sores.
- Crunchy or hard foods: Chips, crackers, crusty bread, and nuts can physically scrape the sore and reopen it.
- Very hot drinks: Coffee, tea, and hot soup increase blood flow and sensitivity in the affected area, making pain worse.
- Alcohol and carbonated drinks: Alcohol dries out the mouth and slows healing. Carbonation adds acidity and fizz that irritates open sores.
Stick to soft, cool, or room-temperature foods. Yogurt, smoothies, scrambled eggs, mashed potatoes, and oatmeal are all easy options that won’t aggravate the sore.
Preventing Future Outbreaks
If you get canker sores repeatedly, switching your toothpaste could help. A systematic review of clinical trials found that toothpastes free of sodium lauryl sulfate (SLS), a common foaming agent, significantly reduced the number of ulcers, the duration of each ulcer, pain levels, and total number of episodes compared to SLS-containing toothpastes. Look for “SLS-free” on the label. Brands like Sensodyne and some natural toothpastes skip this ingredient.
Nutritional gaps play a role too. Vitamin B12 deficiency is linked to recurrent mouth ulcers, along with other oral symptoms like a burning or tingling sensation on the tongue. Deficiencies in iron and folic acid are also known triggers. If you get sores frequently, it’s worth having your levels checked with a simple blood test. Addressing the deficiency often reduces or eliminates recurring outbreaks.
Other practical prevention strategies: avoid biting the inside of your cheeks, use a soft-bristled toothbrush, manage stress (a well-documented trigger), and don’t chew on sharp foods like hard candy or ice that can nick the tissue inside your mouth.
Signs a Mouth Sore Needs Medical Attention
Most mouth blisters resolve within two to three weeks without any intervention. If a sore lasts longer than three weeks, it should be evaluated by a healthcare provider. A sore that won’t heal is one of the key warning signs that distinguishes a benign ulcer from something more serious, including oral cancer.
There are other differences worth knowing. Canker sores are usually flat, painful, and have inflamed red borders. Oral cancers, by contrast, often have a small lump or bump beneath the surface that you can feel, and they’re typically not painful in the early stages. A spot that starts small and grows larger, a white patch that turns red, or a lesion that begins bleeding when it didn’t before are all reasons to get checked promptly.