Several types of over-the-counter products can help with canker sores, from numbing gels that cut pain on contact to protective patches that shield the sore while it heals. Most minor canker sores (smaller than a pea) clear up on their own within two weeks, but the right OTC treatment can make those days far more comfortable and may speed healing along.
Numbing Gels and Liquids
Topical anesthetics containing benzocaine or lidocaine are the most popular OTC choice for immediate pain relief. Products like Orajel and Anbesol numb the sore within seconds, making it easier to eat, drink, and talk. Apply a small amount directly to the ulcer up to four times a day, using the smallest amount that covers the sore.
One important safety note: the FDA warns that benzocaine should not be used on children under 2 years old. In rare cases, benzocaine can cause a serious condition called methemoglobinemia, where the blood carries significantly less oxygen than normal. This risk exists at all concentrations, even low ones. For older children and adults, the products are generally safe when used as directed, but sticking to the four-times-daily limit matters.
Protective Patches and Barriers
If your canker sore is in a spot that constantly rubs against your teeth or cheek, a patch can be more practical than a gel. Products like DenTek Canker Cover use a dissolvable tablet that you press onto the sore with a dry finger. Within about 30 minutes, it forms a clear, gel-like bandage that seals and protects the ulcer for hours before dissolving on its own. This physical barrier keeps food, drinks, and friction from aggravating the sore, which can reduce pain and give the tissue a better environment to heal.
Medicated and Soothing Rinses
Rinsing your mouth is one of the simplest ways to manage canker sore pain, and you have several options depending on what’s in your medicine cabinet.
A basic saltwater or baking soda rinse helps by reducing acid levels in the mouth and calming inflammation. Less acidity means less irritation and a friendlier environment for healing. To make one, dissolve about half a teaspoon of salt or baking soda in a cup of warm water and swish for 30 seconds.
Hydrogen peroxide rinses take this a step further by gently cleaning the ulcer. You can dilute standard 3% hydrogen peroxide with equal parts water and dab it directly on the sore with a cotton swab, then follow with a small dab of Milk of Magnesia. Repeating this three to four times a day can help keep the area clean and soothe discomfort. Pre-made hydrogen peroxide mouth rinses designed for sores (like Oral-B Mouth Sore Oral Rinse) are also available if you prefer something ready to use.
One thing to avoid: mouthwashes that contain alcohol. Alcohol-based rinses can sting and further irritate an open sore. Look for products specifically labeled for mouth sores or sensitive mouths.
Over-the-Counter Pain Relievers
When a canker sore hurts enough to affect your whole day, an anti-inflammatory pain reliever taken by mouth can help more than a topical product alone. Ibuprofen (200 to 400 mg every four to six hours as needed) is a strong first choice because it reduces both pain and the inflammation driving it. Acetaminophen works well for pain relief if you can’t take ibuprofen. You can also combine the two: a fixed-dose OTC product pairs 250 mg ibuprofen with 500 mg acetaminophen in a single dose, which the FDA approved specifically for pain management.
Alum Powder
Alum, the same astringent compound sold in the spice aisle for pickling, is a lesser-known home remedy that has some clinical support. It works by tightening the tissue around the sore, reducing swelling, and lowering the local pH enough to discourage bacterial growth. You can make a paste by mixing a tiny pinch of alum powder with a drop of water, apply it to the sore for about a minute, then rinse your mouth. Studies using alum patches found no side effects, no burning sensation, and no complaints about taste, and patients were able to use it comfortably at home.
Preventing Sores From Coming Back
If you get canker sores repeatedly, two simple changes are worth trying.
First, switch to a toothpaste free of sodium lauryl sulfate (SLS), the foaming agent in most standard toothpastes. A systematic review of clinical trials found that people who used SLS-free toothpaste had significantly fewer ulcers, shorter episodes, and less pain compared to those using regular toothpaste. Brands like Sensodyne, Biotene, and certain Tom’s of Maine varieties skip SLS. This is one of the easiest and most evidence-backed changes you can make.
Second, consider sublingual vitamin B12. A review of multiple studies found that taking 1,000 micrograms of B12 dissolved under the tongue daily led to a significant reduction in the number, duration, and frequency of canker sore outbreaks, particularly after about six months of consistent use. This held true even in people who weren’t deficient in B12, suggesting the vitamin plays a role in mucosal health beyond correcting a simple deficiency. B12 supplements at this dose are inexpensive and widely available.
When a Canker Sore Needs More Than OTC Care
Most canker sores respond well to the options above and disappear within two weeks. But a sore that lasts longer than two weeks, grows larger than about one centimeter (roughly the size of a pea), or keeps coming back in clusters may need professional evaluation. Major canker sores, the kind bigger than a centimeter, tend to be extremely painful and can leave scars. Your doctor or dentist can prescribe stronger treatments, including prescription-strength topical pastes or oral medications, that aren’t available over the counter.