Most mouth blisters heal on their own within one to two weeks, but the right combination of treatments can cut pain significantly and speed up that timeline. The first step is figuring out which type you have, because canker sores and cold sores look different, form in different places, and respond to different treatments.
Identify What You’re Dealing With
Canker sores form inside the mouth, on the inner cheeks, lips, or tongue. They appear as a single round white or yellow sore with a red border. No one knows exactly what causes them, though injuries from biting your cheek, stress, smoking, and deficiencies in iron, folic acid, or vitamin B12 can trigger them.
Cold sores (fever blisters) show up on the outside of the mouth, usually along the border of the lips. They look like a cluster of small, fluid-filled blisters rather than a single sore, and they’re caused by herpes simplex virus type 1 (HSV-1). Cold sores are contagious; canker sores are not. This distinction matters because the treatments that work fastest for each type are quite different.
Fast Relief for Canker Sores
OTC Numbing Gels
For immediate pain relief, look for an over-the-counter oral gel or liquid containing 20% benzocaine. Apply it directly to the sore before meals to numb the area enough to eat comfortably. These products won’t speed healing, but they make the waiting period far more manageable. Reapply as directed on the label, typically up to four times a day.
Topical Steroid Pastes
Prescription-strength steroid pastes designed to stick to wet tissue inside the mouth reduce inflammation and shorten the number of days you’re dealing with an active ulcer. Your dentist or doctor can prescribe one. Apply it after drying the sore gently with a tissue so the paste adheres better. These pastes work best when started at the first sign of a sore, so don’t wait for it to fully develop before asking for a prescription if you get canker sores frequently.
Honey
If you prefer something you already have at home, honey is more than folk wisdom. A randomized clinical trial of 94 patients with minor canker sores found that honey performed better than both a topical steroid and a protective oral paste at reducing ulcer size, pain, and redness. Dab a small amount of raw honey directly onto the sore several times a day, especially before bed when you won’t be eating or drinking for a while.
Salt Water Rinses
Swishing warm salt water is one of the oldest remedies and one that holds up under scrutiny. Salt water doesn’t just “clean” the sore. The chloride ions in the solution stimulate the migration of fibroblasts, the cells your body uses to repair damaged tissue. Lab research shows that a slightly concentrated salt solution (roughly twice the saltiness of normal saline) activates key proteins involved in wound healing and helps these repair cells move toward the injury faster. Dissolve about half a teaspoon of salt in a cup of warm water and rinse for 30 seconds, two to three times a day.
Fast Relief for Cold Sores
Cold sores are viral, so the fastest route to healing involves antiviral treatment. Over-the-counter antiviral creams containing docosanol can shorten an outbreak by roughly a day when applied at the first tingle or itch, before blisters fully form. That early window is critical. Once fluid-filled blisters have appeared, the medication is less effective.
For more significant speed, prescription antiviral pills taken within the first 24 hours of symptoms can reduce healing time by several days. If you get cold sores more than a few times a year, ask your doctor about keeping a prescription on hand so you can start treatment the moment you feel one coming on.
While you’re waiting for a cold sore to heal, keep the area moisturized with petroleum jelly to prevent cracking and bleeding, which slows recovery. Avoid picking at the scab. Cold sores are most contagious when blisters are open, so skip kissing and sharing utensils until the sore has fully crusted over and healed.
What to Avoid
Acidic and spicy foods irritate open sores and can extend healing time. Citrus fruits, tomatoes, vinegar-based dressings, and hot sauce are common offenders. Crunchy foods like chips and toast can physically reinjure a canker sore. Alcohol-based mouthwashes sting and may irritate the tissue further. Switch to an alcohol-free rinse or plain salt water until you’ve healed.
Hydrogen peroxide is sometimes recommended online, but using it at full strength can damage healthy tissue around the sore. If you use it at all, dilute it to a 1:1 ratio with water and limit use to once or twice a day.
Preventing the Next Outbreak
For canker sores, prevention often comes down to identifying your triggers. If you get them after biting your cheek or irritating your gums with a rough toothbrush, switch to a soft-bristled brush and be mindful when chewing. Sodium lauryl sulfate, a foaming agent in many toothpastes, is a known trigger for some people. Switching to an SLS-free toothpaste can reduce how often sores appear. Since deficiencies in iron, folic acid, and vitamin B12 are linked to recurrent canker sores, addressing any nutritional gaps through diet or supplements may help if you get them frequently.
For cold sores, common triggers include sun exposure, stress, illness, and fatigue. Wearing lip balm with SPF and managing stress through sleep and exercise can reduce outbreaks. L-lysine supplements are widely marketed for cold sore prevention, but the evidence is mixed. A review of the clinical data found that doses under 1 gram per day showed no meaningful benefit. Only doses exceeding 3 grams per day, combined with a diet low in arginine (found in nuts, chocolate, and seeds), appeared to reduce recurrence rates and improve symptoms. That’s a high daily dose, so weigh it against the strength of the evidence, which remains limited.
Laser Treatment at the Dentist
If you deal with severe or frequent mouth sores, some dental offices offer low-level laser therapy. The laser reduces pain almost immediately and accelerates tissue repair. A meta-analysis found that laser treatment shortened the complete resolution of oral sores by about four days compared to no treatment. It’s not widely available everywhere, and it’s rarely covered by insurance, but for people who get debilitating sores regularly, it can be worth asking your dentist about.
When a Mouth Sore Needs Attention
Most mouth blisters resolve within two weeks. A sore that lasts longer than three weeks should be evaluated by a doctor or dentist. Persistent ulcers can occasionally indicate something more serious, including oral cancers or chronic infections, and may need a biopsy to rule those out. Similarly, if you develop a fever alongside mouth sores, if they spread rapidly, or if they’re so painful you can’t drink fluids, seek care sooner rather than later.