Most mouth ulcers (canker sores) heal on their own within 10 to 14 days, but the right home care can cut down pain and speed things along. These round, white or yellow sores with a red border show up on the inside of your cheeks, lips, or tongue. They’re not contagious and they’re not cold sores, which are fluid-filled blisters caused by the herpes virus that appear outside the mouth, usually along the lip border.
Saltwater Rinses and Other Home Remedies
The simplest thing you can do right now is a warm saltwater rinse. Dissolve half a teaspoon of table salt in a glass of lukewarm water and swish it gently around the sore for 30 seconds before spitting it out. Repeat this several times a day, especially after meals. It won’t sting as much as you’d expect, and it helps keep the area clean while reducing inflammation.
Honey is another option worth trying. A large review of 17 clinical trials found that honey reduced the development of moderate to severe mouth inflammation by 75% compared to no treatment. The research focused on patients undergoing cancer therapy, but honey’s anti-inflammatory and wound-healing properties apply more broadly. Dab a small amount of honey directly onto the ulcer a few times a day. Medical-grade sterilized honey is the safest choice, though regular honey works for most people with healthy immune systems.
While the ulcer is active, avoid spicy, acidic, and crunchy foods. Tomato sauce, citrus fruits, chips, and hot peppers won’t cause lasting damage, but they’ll irritate the sore and make the pain worse. Stick to soft foods and cool drinks. Using a straw can help liquids bypass the ulcer entirely.
Over-the-Counter Pain Relief
Topical gels, sprays, and ointments containing benzocaine numb the ulcer on contact. Apply a small amount directly to the sore up to four times a day. These products are meant for short-term use only, no more than two days in a row without checking with a pharmacist or doctor. For children under two, benzocaine products aren’t recommended.
You’ll also find OTC protective pastes that form a barrier over the ulcer, shielding it from food and your teeth. These work best when applied after meals and before bed, pressed gently onto the sore with a cotton swab rather than rubbed in.
When You Need Something Stronger
If OTC options aren’t enough, a doctor or dentist can prescribe a steroid dental paste. These pastes reduce inflammation directly at the ulcer site. You apply a small amount after meals and at bedtime, pressing it onto the sore with a cotton swab to form a thin, smooth film. Don’t rub it in, or it crumbles apart. Prescription-strength steroid pastes are particularly useful for larger or more painful ulcers that make eating difficult.
What Causes Mouth Ulcers to Keep Coming Back
If you’re dealing with ulcers repeatedly, something is likely triggering them. One of the most overlooked culprits is your toothpaste. Many toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that strips away the delicate lining of your mouth. Research has shown that SLS toothpaste increases the frequency of recurring mouth ulcers, and one clinical study found four times fewer soft tissue lesions when participants switched to an SLS-free toothpaste. Check your toothpaste’s ingredients and try an SLS-free brand for a few months to see if your ulcers become less frequent.
Nutritional deficiencies are another common driver. Vitamin B12 plays a critical role in maintaining healthy oral tissue, and being low in it can lead to recurrent ulcers, a sore tongue, and cracked corners of the mouth. Iron and zinc deficiencies are also linked to frequent ulcers. If you’re getting sores regularly and can’t pinpoint a trigger, a simple blood test can check these levels.
Other known triggers include biting the inside of your cheek, stress, hormonal changes, and poorly fitting dental work that rubs against soft tissue. Some people notice ulcers flare up after eating certain foods, particularly chocolate, coffee, nuts, or wheat, though these triggers vary from person to person.
Minor vs. Major Ulcers
Most canker sores are minor aphthous ulcers, typically small and shallow. These heal within 10 to 14 days without scarring. Major aphthous ulcers are deeper, larger, and significantly more painful. They can take up to six weeks to heal and sometimes leave a scar. If your ulcer is unusually large or deep, a doctor can prescribe stronger treatments to manage pain and inflammation during that longer healing window.
Signs That Need Medical Attention
A single ulcer that heals within two weeks is almost always harmless. But an ulcer that persists beyond two weeks after you’ve removed any obvious irritants (sharp tooth edges, ill-fitting dentures) should be evaluated by a dentist or doctor. Persistent ulcers are sometimes biopsied to rule out other conditions.
Other red flags include ulcers that bleed easily, grow rapidly, or feel hardened or fixed to deeper tissue. Sores that appear red, or a mix of red and white, and don’t respond to treatment also warrant a closer look. Multiple ulcers appearing at the same time, recurring frequently, or accompanied by fever or feeling generally unwell can signal an underlying condition that goes beyond a simple canker sore.