Most canker sores heal on their own within 10 to 14 days, but the pain can make eating, drinking, and talking miserable in the meantime. The good news is that several simple strategies can significantly reduce that pain, and most of them use things you already have at home.
Why Canker Sores Hurt So Much
A canker sore is a break in the lining of your mouth, which exposes the sensitive tissue underneath to everything that passes through: food, drinks, saliva, and bacteria. Once that barrier is breached, bacteria flood the area and immune cells rush in, creating intense local inflammation. That inflammation sensitizes the surrounding nerve endings, which is why even lukewarm soup or a gentle brush of your tongue can trigger sharp, disproportionate pain.
Saltwater and Baking Soda Rinses
A simple mouth rinse is one of the fastest, cheapest ways to take the edge off. 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 salt or baking soda alone in the same ratio. Swish gently for 30 seconds and spit. Repeat every four to six hours, or more often if you need to.
Salt draws fluid out of swollen tissue, which temporarily reduces inflammation. Baking soda neutralizes acids in the mouth that irritate the open sore. Neither will sting the way you might expect if you use the right dilution. Straight salt applied to the sore will burn intensely and isn’t necessary.
Over-the-Counter Numbing Products
Topical gels and ointments containing benzocaine are widely available and work by temporarily blocking pain signals from the nerve endings in and around the sore. Apply the gel directly to the ulcer up to four times a day. The numbing effect kicks in within a minute or two, making it easier to eat a meal or get through a conversation.
One important safety note: the FDA warns that benzocaine products should never be used on children under 2 years old. In rare cases, benzocaine can cause a serious condition where the blood carries significantly less oxygen than normal. For adults and older children, this risk is very low when used as directed, but stick to the recommended frequency and don’t swallow more product than necessary.
Protective Barriers and Patches
Pain from a canker sore often spikes when food or your teeth physically rub against it. Oral adhesive patches and gel-based “liquid bandages” create a physical shield over the ulcer, blocking contact with irritants while keeping medication against the tissue. You press them onto the dry sore and they stick for several hours. Some contain a mild pain reliever; others simply act as a barrier. Either way, they’re especially useful right before meals.
Foods to Avoid While You Heal
Acidic and spicy foods are the biggest offenders. Coffee, oranges, grapefruit, pineapple, and tomato-based sauces all lower the pH in your mouth and directly irritate exposed tissue. Spicy dishes do the same through chemical irritation. Crunchy or sharp-edged foods like chips, pretzels, and nuts can physically scrape the sore and reset the healing clock.
Stick to soft, bland, cool foods when the pain is at its worst. Yogurt, oatmeal, scrambled eggs, mashed potatoes, and smoothies are all easy on the mouth. Drinking through a straw can help liquids bypass the sore entirely if it’s on your lip or the front of your mouth.
Switch Your Toothpaste
Many popular toothpastes contain sodium lauryl sulfate (SLS), a foaming agent also found in shampoos and household cleaners. SLS is a known soft tissue irritant, and for people prone to canker sores, it can trigger new outbreaks or make existing ones worse. If you get canker sores frequently, switching to an SLS-free toothpaste is one of the simplest changes you can make. Several brands market themselves as SLS-free, and you can verify by checking the inactive ingredients list on the back of the tube.
Nutritional Deficiencies Worth Checking
Occasional canker sores are normal. But if you’re getting them repeatedly, your body may be running low on certain nutrients. Vitamin B12 deficiency is one of the more common nutritional links to recurrent canker sores. Low levels of iron, zinc, and folate (vitamin B9) are also associated with frequent outbreaks. All four nutrients play roles in immune function, wound healing, or healthy cell turnover in the mouth’s lining.
If you’re dealing with canker sores every few weeks, it’s worth asking your doctor to check these levels with a blood test. Correcting a deficiency through diet or supplements can reduce how often sores appear in the first place, which is a better long-term strategy than treating each one as it comes.
Signs a Canker Sore Needs Medical Attention
Most canker sores are small, round, and gone within two weeks. But according to the Cleveland Clinic, you should contact a healthcare provider if a sore lasts longer than two weeks, is larger than about one centimeter (bigger than a pea), or keeps coming back in clusters. Unusually large or persistent ulcers can sometimes signal an underlying condition, and a provider may prescribe a stronger topical treatment or run tests to identify what’s driving them.