Most lip ulcers are canker sores, and the majority heal on their own within 10 to 14 days. But you can speed up healing and cut down on pain with a few straightforward treatments, from saltwater rinses to over-the-counter numbing gels. The key is starting early, avoiding irritants, and knowing when a sore needs professional attention.
First, Identify What You’re Dealing With
The two most common types of mouth sores look and behave differently, and the treatment depends on which one you have. Canker sores form inside the mouth, on the inner lips, cheeks, or tongue. They appear as a single round white or yellow sore with a red border. Cold sores (fever blisters) form on the outside of the mouth, usually along the lip border, and show up as clusters of small fluid-filled blisters.
Canker sores have no single known cause. They can be triggered by minor injuries (biting your lip, a sharp chip), stress, smoking, or nutritional deficiencies. Cold sores are caused by herpes simplex virus type 1 (HSV-1) and require antiviral treatment rather than the approaches below. If your sore is a cluster of blisters on the outer lip, you’ll want antiviral options instead. The rest of this article focuses on canker sores and similar ulcers that form on or inside the lips.
Saltwater and Baking Soda Rinses
A warm saltwater rinse is one of the simplest ways to reduce pain and keep the ulcer clean. Mix 1/4 teaspoon of salt and 1/4 teaspoon of baking soda into one cup of warm water. Swish it gently around the sore for 15 to 30 seconds, then spit. Repeat this three to four times a day, especially after meals. The salt draws out fluid to reduce swelling, while the baking soda creates a mildly alkaline environment that discourages bacterial growth. It won’t taste great, but it works.
Honey as a Topical Treatment
Applying honey directly to a lip ulcer can meaningfully shorten healing time. In one study comparing honey to a standard steroid paste and a plain protective base, the honey-treated group saw ulcer size reduction in an average of about 2.7 days, compared to nearly 6 days for the steroid group and 7 days for the control. Honey promotes new blood vessel formation at the wound site and speeds up the regrowth of surface tissue. Dab a small amount of raw or medical-grade honey onto the ulcer a few times a day. Manuka honey is a popular choice, though the research used honey gel preparations rather than a specific brand.
Over-the-Counter Pain Relief
Numbing gels and pastes containing benzocaine can take the edge off, especially before eating. Apply a small amount directly to the ulcer using a clean fingertip or cotton swab. Don’t use it more than four times a day, and use the smallest amount that relieves pain. The FDA has flagged benzocaine for a rare but serious blood condition, so use it sparingly and avoid it entirely in children under two.
If you prefer to skip benzocaine, standard oral pain relievers like ibuprofen can help with both pain and inflammation. Protective mouth rinses and gels that form a barrier over the sore (look for products marketed specifically for canker sores) can also shield the ulcer from food and saliva irritation.
Prescription Options for Severe Ulcers
When an ulcer is large, extremely painful, or keeps coming back, a dentist or doctor can prescribe a steroid dental paste. This type of paste works by reducing inflammation directly at the sore. You apply it after meals and at bedtime by pressing a small amount onto the ulcer with a cotton swab to form a thin film. Don’t rub it in, as that causes it to crumble. The paste sticks to the moist tissue and delivers the steroid over time.
Major canker sores, which are larger and deeper than the common type, can persist for up to six weeks and sometimes leave scars. These almost always warrant a prescription rather than home treatment alone.
Switch to an SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it’s a known trigger for recurrent canker sores. A systematic review of clinical trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each episode, overall pain, and the frequency of flare-ups. If you get lip ulcers more than a few times a year, this single change is one of the most effective preventive steps you can take. Several major brands sell SLS-free versions, often labeled “gentle” or “sensitive.”
Check for Nutritional Deficiencies
Roughly 18% of people with recurrent canker sores turn out to be deficient in vitamin B12, folate, or iron. In a study of 130 patients screened for these deficiencies, 23 were found to be low in one or more. When those 23 patients received the specific nutrient they were missing, 15 experienced complete remission and the remaining eight showed clear improvement. B12 and folate deficiencies responded the fastest, while iron deficiency took longer to correct.
If your ulcers keep returning, a simple blood test can check these levels. You don’t need to megadose supplements preventively, but correcting an actual deficiency can stop the cycle of recurring sores entirely.
What to Avoid While Healing
Certain foods and habits slow healing or intensify pain. Acidic foods like citrus, tomatoes, and vinegar-based dressings irritate the exposed tissue. Spicy foods, salty snacks, and rough-textured items like chips or crusty bread can physically aggravate the sore. Alcohol-based mouthwashes also sting and may delay recovery. Stick to bland, soft foods and gentle oral care products until the ulcer closes.
When a Lip Ulcer Needs Medical Attention
A standard canker sore should begin improving within a week and fully heal within two weeks. Any mouth ulcer that lasts longer than three weeks should be evaluated by a doctor or dentist, as persistent ulcers can indicate malignancy or chronic infection and typically require a biopsy to rule out serious conditions. You should also seek care if you develop a fever alongside the ulcer, if the sore is unusually large (bigger than a centimeter), if you can’t eat or drink due to pain, or if ulcers appear in frequent clusters with little break between episodes.