Most canker sores last 7 to 14 days and heal on their own without scarring. Pain is usually worst during the first few days, then improves as the sore shrinks, although a larger or deeper sore can take several weeks to fully heal.
If a mouth sore is painful, persistent, or keeps returning, a dental exam can identify likely causes and point to the most helpful next steps for relief and prevention. Dental Studio of Palm Harbor in Palm Harbor, FL offers focused evaluation and treatment planning to relieve pain, reduce recurrence, and protect oral health.
A canker sore, also called an aphthous ulcer, is a shallow sore that forms on the soft tissues inside the mouth. It often looks round or oval, with a white, yellow, or gray center and a red border.
Stage | Typical Timing | What To Expect |
|---|---|---|
Early symptoms | Hours to 1 day | Tingling, burning, or tenderness may start before the sore is visible |
Most painful period | Days 1 to 4 | The open sore may sting with eating, drinking, brushing, or talking |
Healing period | Days 5 to 14 | Pain and redness usually ease as the tissue closes |
Longer healing | 2 to 6 weeks | Large, deep, or clustered sores may take longer and can sometimes scar |
Minor canker sores are the most common type. They are usually small and heal within about two weeks.
Major canker sores are larger and deeper, so they often last longer. Herpetiform canker sores appear as many tiny ulcers that may join together into a larger sore area.
The exact cause of canker sores is not always clear. Common triggers include cheek biting, dental work, braces, a sharp tooth edge, stress, hormonal changes, and acidic or spicy foods.
Some people also react to toothpaste that contains sodium lauryl sulfate. Repeated irritation can keep the sore inflamed and slow healing.
Recurring or slow-healing sores may sometimes be linked to low iron, folate, vitamin B12, or zinc. Less often, frequent ulcers can occur with digestive, immune, or inflammatory conditions, which is why repeated episodes deserve professional evaluation instead of repeated self-treatment alone.
Regular preventive dentistry visits may also help identify triggers, improve home-care habits, and reduce irritation that contributes to recurrence.
Canker sores are not contagious and are not caused by the herpes virus. Cold sores are different and usually form as fluid-filled blisters on or around the lips.
Canker sores develop inside the mouth on soft tissue, such as the cheeks, lips, tongue, soft palate, or the base of the gums. Cold sores more often appear outside the mouth and can spread to other people.
Most treatment focuses on reducing pain while the tissue heals. Good home care can also help prevent extra irritation that makes the sore last longer.
For severe, persistent, or frequently recurring sores, a dentist or physician may prescribe a topical corticosteroid or another treatment. These treatments may reduce pain and inflammation, but they do not always make the sore disappear right away or prevent every future episode.
Schedule a dental exam or medical visit if a mouth sore has not healed within two weeks, keeps coming back, becomes unusually large, or seems to be getting worse instead of better. You should also be evaluated if pain makes it hard to eat, drink, sleep, speak, or brush your teeth.
Seek prompt care if you also have fever, spreading swelling, pus, swollen lymph nodes, a rash, eye symptoms, genital sores, unexplained weight loss, persistent diarrhea, or multiple severe ulcers. Get urgent medical attention for trouble breathing or swallowing, major facial or neck swelling, or signs of dehydration such as very little urination, dizziness, or not being able to keep fluids down.
A dentist can also check whether the area is truly a canker sore or irritation from a sharp tooth, broken restoration, denture, or orthodontic appliance. If there may be trauma from a tooth, reviewing cracked tooth symptoms can also be helpful.
Any unexplained mouth ulcer, red or white patch, lump, or tissue change that lasts longer than two weeks should be examined. Some more serious conditions can look similar to a routine canker sore at first.
A consultation is especially helpful if sores happen several times a year, appear after dental treatment, or keep returning in the same spot. Bring notes about timing, possible food or stress triggers, medications, other symptoms, and photos if you have them.
During the visit, the dentist will usually review your history and examine the area for trauma, infection, or another tissue problem. Depending on the findings, you may be advised on symptom relief, smoothing a sharp dental surface, medical follow-up for blood testing, referral, or biopsy of a persistent unclear lesion.
Timely evaluation can clarify the cause, reduce ongoing irritation, and help rule out problems that need more than home care.
If your sore has not healed in two weeks or is unusually painful, arrange a dental exam to get a clear diagnosis and tailored treatment. Call Dental Studio of Palm Harbor for general dentistry in Palm Harbor, FL at (727) 786-1077 or book online for same-day or next-available appointments.
A very small sore may feel much better within three days, but full healing usually takes 7 to 14 days. If it quickly worsens or becomes unusually painful, it should be checked.
No. Canker sores are not contagious and cannot be spread by kissing, shared utensils, or other contact.
Recurring sores may be related to stress, minor trauma, certain foods, nutritional deficiencies, medications, or an underlying health condition. A dentist or physician can help evaluate frequent, severe, or predictable recurrences.
No. A canker sore is an ulcer, not a pimple or blister, so there is nothing useful to pop. Trying to open or scrape it can increase pain, bleeding, irritation, and healing time.
Canker sores usually appear as open ulcers inside the mouth and are not contagious. Cold sores usually begin as clustered blisters around the lips, are caused by herpes simplex virus, and can spread to others.
