Most mouth blisters heal on their own within one to two weeks, but you can speed up relief and reduce pain with a few targeted steps. The right approach depends on what type of blister you’re dealing with, since the two most common kinds (canker sores and cold sores) have different causes and respond to different treatments.
Identify What You’re Dealing With
Before treating a mouth blister, it helps to know which kind you have. The two most common types look and behave differently.
Canker sores appear inside the mouth, usually on the inner cheeks, lips, or tongue. They’re typically a single round sore with a white or yellow center and a red border. The cause isn’t fully understood, but they can be triggered by injury (like biting your cheek), stress, smoking, or deficiencies in iron, folic acid, or vitamin B12. They are not contagious.
Cold sores (fever blisters) show up on the outside of the mouth, around the lips. They look like a cluster of small, fluid-filled blisters and are caused by herpes simplex virus, usually type 1. They are contagious, especially when the blisters are open and weeping.
This distinction matters because canker sores respond well to soothing rinses and protective barriers, while cold sores benefit from antiviral treatment.
Saltwater and Baking Soda Rinses
A simple rinse is one of the most effective home treatments for canker sores. It reduces bacteria around the sore, lowers acidity in the mouth, and helps keep the area clean so it can heal faster. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish a mouthful gently for 30 seconds and spit. You can repeat this several times a day, especially after meals.
This rinse won’t sting as much as you might expect. The baking soda neutralizes acid in the mouth, which is part of what makes the sore painful in the first place. You can store leftover solution in a sealed container at room temperature and use it throughout the day.
Over-the-Counter Pain Relief
Numbing gels and ointments containing benzocaine are widely available and work well for short-term pain relief from canker sores. Apply the gel directly to the sore up to four times a day. Don’t exceed that. Lozenges with the same ingredient can also help if the sore is in a hard-to-reach spot. Let the lozenge dissolve slowly in your mouth, and you can use one every two hours as needed.
These products don’t speed healing, but they make eating and talking far more comfortable while the sore resolves on its own. Look for oral-specific products rather than general topical creams, since formulations designed for the mouth stick to wet tissue better.
Treating Cold Sores With Antivirals
Cold sores on or around the lips respond to antiviral creams. The over-the-counter option is a cream that works by blocking the virus from entering healthy cells. The key with any antiviral treatment is timing: apply it as soon as you feel the first signs, like tingling, burning, or tightness on the lip, before blisters fully form. Starting early can shorten an outbreak by a day or more.
Apply the cream five times a day until the sore heals. If you get frequent cold sores (more than a few times a year), a doctor can prescribe oral antiviral medication that works more aggressively to shorten outbreaks and reduce how often they return.
Protective Barriers and Patches
Oral patches that stick directly over a canker sore create a physical shield between the sore and everything else in your mouth: food, teeth, your tongue. This reduces pain significantly and keeps the sore from getting irritated further. These patches use materials that adhere to the wet lining of the mouth and dissolve slowly over several hours.
You can find these at most pharmacies. They’re especially useful if a sore is in a spot that constantly rubs against your teeth or gets hit by food when you chew. Some patches also contain a mild numbing agent for added relief.
What to Avoid While Healing
Acidic foods like citrus, tomatoes, and vinegar-based dressings will aggravate an open sore and make the pain noticeably worse. Spicy foods and anything with sharp edges (chips, crusty bread, hard pretzels) can re-injure the tissue and delay healing. Stick to softer, blander foods until the sore closes up.
Alcohol-based mouthwashes can also irritate mouth blisters. If you want to use a mouthwash while healing, choose an alcohol-free version or stick with the saltwater rinse described above.
Nutritional Gaps That Cause Recurring Sores
If you get canker sores frequently, the problem may not be in your mouth at all. Deficiencies in vitamin B12, folic acid, and iron are linked to recurring mouth ulcers. Low levels of B12 and folate can also cause a sore, red tongue alongside the ulcers.
You don’t necessarily need supplements right away. Foods rich in B12 include meat, fish, eggs, and dairy. Leafy greens, beans, and fortified cereals are good sources of folate. Iron comes from red meat, lentils, and spinach. If you eat a varied diet and still get frequent sores, a simple blood test can check whether a deficiency is driving the problem.
How Long Healing Takes
Minor canker sores typically heal within one to two weeks without any treatment. Pain is usually worst in the first few days and gradually fades as the sore shrinks. Cold sores follow a similar timeline, progressing from blister to crust to healed skin over about 7 to 10 days.
If a mouth sore hasn’t improved after three weeks, or hasn’t fully resolved within a month, have it examined by a dentist or doctor. A sore that lingers that long, especially if it feels firm or keeps growing, needs professional evaluation to rule out something more serious than a common blister.