The fastest relief for a canker sore comes from a topical numbing gel containing 20% benzocaine, available at any drugstore without a prescription. But numbing is only one approach. Depending on the size and stubbornness of your sore, you have several options ranging from kitchen-shelf rinses to prescription-strength pastes.
Most canker sores are minor, meaning they’re under a centimeter across and heal on their own within 10 to 14 days. Everything you put on a canker sore is really about managing pain and keeping the area clean while your body does the repair work. Larger sores, which can take up to six weeks to heal, sometimes need a stronger approach.
Over-the-Counter Numbing Gels
Products like Red Cross Canker Sore Medication and Orajel use benzocaine at 20% concentration to numb the area on contact. You apply a small amount directly to the sore, and the pain relief kicks in within a minute or two. The effect is temporary, usually lasting 30 to 60 minutes, so you’ll likely reapply several times a day, especially before meals.
There are also protective pastes and patches that form a barrier over the sore. These work less by numbing and more by shielding the raw tissue from food, drinks, and your teeth. Some combine a numbing agent with a protective coating, which gives you both benefits at once. Look for products labeled specifically for canker sores rather than general oral pain, since they’re formulated to stick to wet tissue inside the mouth.
Salt Water and Baking Soda Rinses
A simple rinse is one of the most effective things you can do at home, and it costs almost nothing. Memorial Sloan Kettering Cancer Center recommends mixing 1 teaspoon of salt and 1 teaspoon of baking soda into 1 quart (4 cups) of water. You can also use either ingredient on its own at the same ratio: 1 teaspoon per quart. Swish for 30 seconds and spit. Repeat several times a day, particularly after eating.
Salt water draws fluid out of inflamed tissue, which temporarily reduces swelling. Baking soda neutralizes acids in the mouth that can irritate the open sore. Neither will dramatically speed healing, but both reduce discomfort and help keep the area clean. The rinse should sting slightly at first, then feel soothing.
Diluted Hydrogen Peroxide
Hydrogen peroxide acts as a mild antiseptic and helps remove debris from the sore’s surface. Start with the standard 3% hydrogen peroxide sold in brown bottles at drugstores, then mix equal parts peroxide and water to bring it down to 1.5%. Dab this directly on the sore with a cotton swab, or swish a small amount and spit. Don’t swallow it, and don’t use it at full strength, since undiluted peroxide can irritate healthy tissue around the sore.
Honey
Applying a small amount of honey directly to a canker sore is a folk remedy that has some research behind it. A systematic review found that honey performed about as well as standard topical treatments for reducing pain and ulcer size in people with recurring canker sores, with no reported side effects. Honey has natural anti-inflammatory and antimicrobial properties, and its thick consistency helps coat and protect the sore. Apply it a few times a day, letting it sit as long as possible before eating or drinking. Plain, unprocessed honey works fine.
Prescription Options for Stubborn Sores
If over-the-counter products aren’t cutting it, a doctor or dentist can prescribe a steroid dental paste. These pastes reduce inflammation directly at the sore, which both eases pain and can shorten healing time. You press a small amount onto the sore (typically at bedtime, so it stays in place longer), and the steroid calms the immune response that’s driving the inflammation.
Prescription rinses containing stronger antiseptic or anti-inflammatory ingredients are another option. These are most commonly used for people who get frequent or severe outbreaks rather than a one-off sore.
What to Avoid Putting on a Canker Sore
Skip anything that contains alcohol as a primary ingredient, including most standard mouthwashes. Alcohol burns on contact with open tissue and can actually slow healing by drying out the area. Spicy, acidic, or abrasive foods (chips, citrus, tomato sauce) aren’t topical treatments, but they’re worth mentioning because they’ll aggravate the sore and make it feel worse.
Don’t try to cauterize the sore yourself with anything sharp, chemical, or extremely hot. While chemical cautery is something a dentist can do in a controlled setting, DIY attempts typically cause more tissue damage.
Nutrient Deficiencies and Recurring Sores
If you get canker sores repeatedly, the issue might not be on the surface at all. Vitamin B12 deficiency has a strong association with recurrent canker sores. In one study, over half of patients with recurring oral ulcers had B12 levels below normal, compared to none in the control group. Low iron stores and folate deficiency are also linked to frequent outbreaks, though the evidence is less dramatic for those nutrients.
If you’re dealing with sores that keep coming back, it’s worth asking about a blood test to check B12, ferritin (a marker of iron stores), and folate levels. Correcting a deficiency can sometimes reduce or eliminate recurrences entirely, which is a far better long-term fix than treating each sore as it appears.
Signs a Canker Sore Needs Medical Attention
Most canker sores resolve without any intervention. But certain patterns signal something beyond a routine sore: a sore lasting longer than two weeks, unusually large sores, new sores developing before old ones heal, high fever accompanying the sores, pain that doesn’t respond to any self-care, or difficulty eating and drinking. Sores that extend onto the outer border of your lips are also worth getting checked, since that location is more typical of cold sores (which are viral and require different treatment). If a sharp tooth or dental appliance keeps triggering sores in the same spot, a dentist can smooth or adjust the source of irritation.