Most canker sores heal on their own within one to two weeks, but the right combination of home remedies and over-the-counter products can cut down pain and speed that timeline. What works best depends on whether you’re dealing with a single sore or recurring outbreaks, so this guide covers both immediate relief and longer-term prevention.
Salt Water and Baking Soda Rinses
The simplest remedy is also one of the most effective. A saltwater rinse reduces inflammation and lowers the acid level inside your mouth, creating a less hostile environment for the healing tissue. Mix 1 teaspoon of salt into 1 cup of warm water, swish gently for 30 seconds, and spit. You can repeat this several times a day, especially after meals when food debris irritates the sore.
Baking soda works through a similar mechanism. Dissolve 1 teaspoon of baking soda in half a cup of warm water and use it as a rinse. Some people also make a thick paste with baking soda and a few drops of water and dab it directly on the sore. Both approaches help neutralize the acids in your mouth that make the raw tissue sting.
Over-the-Counter Numbing Products
Benzocaine is the active ingredient in most canker sore gels and liquids you’ll find at a pharmacy. It temporarily numbs the surface of the sore so you can eat, drink, or talk without wincing. These products come in gels, pastes, sprays, and swabs. Apply directly to the sore up to four times a day, and don’t use them for more than two consecutive days without checking with a doctor or dentist.
Protective pastes that form a barrier over the sore can also help. They shield the raw tissue from contact with food, teeth, and your tongue, which is often what causes the sharpest bursts of pain throughout the day. Look for products labeled specifically for mouth sores rather than general oral pain relievers.
Avoiding Foods That Make It Worse
Acidic and spicy foods are the biggest offenders. Citrus fruits, tomatoes, vinegar-based dressings, hot peppers, and salty chips all irritate the exposed tissue and can make a small sore feel enormous. Stick to softer, blander foods while the sore is at its worst. Yogurt, scrambled eggs, oatmeal, and smoothies are easy choices that won’t sting on contact.
Very hot drinks and crunchy foods can also reopen the sore or delay healing. Let coffee and tea cool down before sipping, and avoid sharp-edged snacks like tortilla chips and crusty bread until the sore has closed over.
Switch to an SLS-Free Toothpaste
If you get canker sores repeatedly, your toothpaste may be part of the problem. Sodium lauryl sulfate (SLS) is a foaming agent in most conventional toothpastes, and it has a well-documented connection to recurrent canker sores. A systematic review of clinical trials found that switching to an SLS-free toothpaste reduced the number of ulcers by about one per cycle, shortened healing time by roughly two days, and significantly decreased pain compared to regular toothpaste.
Several brands now sell SLS-free options, and they’re widely available at drugstores and online. If you notice a pattern of sores appearing every few weeks, this single change is one of the easiest and most evidence-backed things you can try.
Nutritional Deficiencies That Fuel Outbreaks
Recurring canker sores are sometimes a signal that your body is low on certain vitamins or minerals. The nutrients most closely linked to outbreaks are iron, vitamin B12, folate, and zinc. Each plays a role in tissue repair and immune function, and running low on any of them can slow wound healing and make your mouth lining more vulnerable.
Iron deficiency is especially common and can show up alongside fatigue and weakness. B12 deficiency tends to affect people who eat little or no animal products, since B12 occurs naturally in meat, poultry, and dairy. Folate, found in fruits, vegetables, and legumes, supports cell growth and repair. Zinc, concentrated in meat and seafood, strengthens immune defenses and helps wounds close faster. Calcium deficiency has also been associated with canker sores, though the connection is less well understood.
If your sores keep coming back and you suspect a nutritional gap, a simple blood test can check your levels. Correcting a deficiency often reduces the frequency of outbreaks noticeably.
Prescription Options for Severe Sores
When a canker sore is large, extremely painful, or keeps recurring despite home care, a dentist or doctor can prescribe stronger treatments. Steroid-based dental pastes reduce inflammation directly at the sore site and tend to work faster than anything available over the counter. These are applied as a thin film over the ulcer, usually at bedtime, so the medication stays in contact with the tissue while you sleep.
For frequent, severe outbreaks, a prescription steroid mouth rinse may be recommended. This allows you to treat multiple sores at once and reach spots that are hard to cover with a paste. The goal is to calm the immune response that’s driving the inflammation and let the tissue repair itself.
Laser Treatment at the Dentist
Some dental offices now offer low-level laser therapy for canker sores. The procedure takes just a few minutes: a small laser is directed at the sore, and the energy promotes faster tissue healing while reducing pain. Many patients report near-immediate relief after a single session. The treatment is painless and doesn’t require anesthesia. It’s not available everywhere and typically isn’t covered by insurance, but it’s worth asking about if you get frequent or unusually painful sores.
When a Canker Sore Needs Attention
Most canker sores are harmless and predictable: they hurt for a few days, then gradually fade. But certain signs suggest something more is going on. A sore that lasts longer than two weeks, grows larger than a centimeter (roughly the size of a pea), or comes with a high fever warrants a call to your doctor or dentist. These could indicate an underlying condition driving the sores, or your provider may want to confirm the growth is actually a canker sore and not something else. Sores that spread unusually fast or make it difficult to drink enough fluids also deserve professional evaluation.