The fastest way to make a canker sore hurt less is to apply an over-the-counter numbing gel containing 20% benzocaine directly to the sore. This creates a protective film that blocks pain for a few hours. But beyond numbing, several other approaches can reduce irritation, speed healing, and keep you comfortable until the sore closes on its own, which typically takes 10 to 14 days for standard canker sores.
Topical Numbing Gels
Over-the-counter mouth sore gels with 20% benzocaine are the most direct way to cut the pain. For best results, dry the area with a clean tissue or cotton ball before applying. This helps the gel form a longer-lasting film over the ulcer. You can reapply up to four times a day. The coating both numbs the nerve endings and acts as a physical barrier between the sore and everything in your mouth, including food, your teeth, and your tongue.
These products are sold under various brand names at any pharmacy. Look for “oral pain relief” gels or pastes specifically labeled for mouth sores. Some versions come with small applicator tips that make it easier to target the sore without smearing gel across healthy tissue.
Salt Water and Baking Soda Rinses
A simple rinse can reduce the acidity in your mouth that irritates an open sore. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish gently for 30 seconds and spit. The baking soda shifts your mouth toward a more alkaline environment, which helps reduce irritation around the ulcer. The salt draws fluid from inflamed tissue, which can temporarily shrink swelling.
You can use this rinse several times a day, especially after meals when food particles and acids are most likely sitting against the sore. It won’t numb anything, but many people find it takes the edge off the constant low-grade sting that makes canker sores so annoying between meals.
Foods That Make It Worse
A canker sore is an open wound inside your mouth, and certain foods hit it like rubbing alcohol on a cut. The biggest offenders fall into a few categories:
- Acidic foods: Citrus fruits, tomatoes, vinegar-based dressings, and anything pickled. The acid directly irritates exposed tissue.
- Spicy foods: Chili peppers, hot sauce, and heavily seasoned dishes. These trigger pain receptors that are already raw.
- Crunchy or sharp foods: Chips, pretzels, crackers, toast, and granola. Hard edges can scratch the sore or the tissue around it, making things worse or even creating new abrasions.
- Coffee and alcohol: Both dry out your mouth, reducing the saliva that naturally buffers and protects oral tissue.
While the sore is active, lean toward soft, cool, bland foods. Yogurt, smoothies, scrambled eggs, mashed potatoes, and oatmeal are all easy on the mouth. Drinking through a straw can help liquids bypass a sore on your lip or the front of your mouth.
Honey and Other Natural Options
Honey has mild antibacterial and anti-inflammatory properties, and dabbing a small amount directly on a canker sore several times a day may reduce pain and swelling. Use raw, unpasteurized honey if possible. It forms a natural coating over the sore similar to what a medicated gel does.
Alum powder, the same compound used in pickling, is another home remedy with some clinical backing. A study using mucosal patches containing alum found significant reductions in both pain and ulcer size over five days compared to a placebo. You can make a simple paste by mixing a tiny pinch of alum powder with a drop of water and applying it to the sore for about a minute before rinsing. It stings initially but may help the sore shrink faster. Most grocery stores carry alum in the spice aisle.
Ice and Cold Foods
Holding a small ice chip against the sore numbs the area without any medication. Let the ice dissolve slowly rather than pressing hard. Popsicles and cold water work similarly. Cold constricts blood vessels in the tissue, which temporarily reduces inflammation and dulls pain signals. This is especially useful right before meals, giving you a short window to eat more comfortably.
How Long the Pain Lasts
Most canker sores are the minor type. They start as a tingling or burning spot, develop into a visible ulcer within a day or two, and peak in pain around days 3 to 5. After that, the pain gradually fades as the tissue rebuilds. Full healing takes 10 to 14 days, and no scar is left behind. Some people get a milder version that resolves in just 2 to 3 days.
Major canker sores are less common but significantly more painful. They’re larger, deeper, and can take up to 6 weeks to heal. If your sore is bigger than a pencil eraser, extremely deep, or hasn’t started improving after two weeks, it’s worth having a dentist or doctor look at it.
Preventing the Next One
If you get canker sores repeatedly, it’s worth looking at a few common triggers. Low levels of iron, folate, and vitamin B12 have all been linked to recurrent canker sores. You don’t necessarily need blood work to act on this. Eating more leafy greens, beans, eggs, and fortified cereals covers all three nutrients. If sores keep coming back despite dietary changes, a simple blood panel can check whether a specific deficiency is driving the pattern.
Physical trauma is another frequent trigger. Biting the inside of your cheek, brushing too aggressively with a hard-bristled toothbrush, or getting poked by orthodontic wires can all kick off a sore. Switching to a soft-bristled brush and using a toothpaste without sodium lauryl sulfate (a foaming agent that irritates some people’s mouth tissue) are two low-effort changes that reduce recurrence for many people.
Canker Sores vs. Cold Sores
These two get confused constantly, but they’re completely different conditions requiring different treatment. Canker sores appear inside the mouth as single round white or yellow ulcers with a red border. Cold sores (fever blisters) appear outside the mouth, typically around the lip border, as clusters of small fluid-filled blisters. Cold sores are caused by the herpes simplex virus and are contagious. Canker sores are not viral and cannot be spread to another person. If your sore is on the outside of your lips or looks like a cluster of tiny blisters rather than a single ulcer, the treatments in this article won’t help, and you’ll want an antiviral product instead.