How Long Does It Take for a Canker Sore to Heal?

Quick Answer

7–14 days is the typical healing time for minor canker sores, which account for about 80% of all cases. They heal on their own without scarring. Major canker sores (larger than 1 cm) can take 4–6 weeks to heal and may leave scars. Herpetiform canker sores, which appear as clusters of tiny ulcers, typically heal in 1–2 weeks. Over-the-counter treatments can reduce pain and speed healing by a few days.

Healing Time by Type

Type	Size	Frequency	Healing Time	Scarring
Minor	Less than 1 cm	80% of cases	7–14 days	No
Major	Greater than 1 cm, deeper	10% of cases	4–6 weeks	Often yes
Herpetiform	Clusters of 10–100 tiny ulcers (1–3 mm each)	10% of cases	7–14 days	Rarely

Canker Sore Progression Timeline (Minor)

Day	What to Expect
Day 1–2	Tingling or burning sensation before the sore appears
Day 2–3	A small, round or oval ulcer forms with a white or yellowish center and red border
Day 3–5	Pain peaks, eating and talking may be uncomfortable
Day 5–7	Pain begins to decrease, sore starts shrinking
Day 7–10	Significant healing, sore much smaller, minimal pain
Day 10–14	Fully healed, no scar

What Causes Canker Sores?

The exact cause is unknown, but common triggers include:

• Mouth trauma — biting your cheek, aggressive brushing, dental work, braces
• Stress — one of the most commonly reported triggers
• Acidic or spicy foods — citrus fruits, tomatoes, pineapple, spicy dishes
• Sodium lauryl sulfate (SLS) — a foaming agent in many toothpastes
• Hormonal changes — menstrual cycle, pregnancy
• Nutritional deficiencies — iron, vitamin B12, zinc, or folic acid deficiency
• Immune system dysfunction — canker sores are more common in people with weakened immunity
• Food sensitivities — gluten, chocolate, coffee, nuts, cheese
• Helicobacter pylori — the same bacteria that causes stomach ulcers

Canker Sores vs. Cold Sores

Feature	Canker Sore	Cold Sore
Location	Inside the mouth	Outside the mouth (lips, around mouth)
Appearance	White/yellow ulcer with red border	Fluid-filled blisters that crust over
Cause	Not infectious, unknown triggers	Herpes simplex virus (HSV-1)
Contagious	No	Yes
Treatment	Topical pain relief, anti-inflammatory	Antiviral medication

Treatment Options

Over-the-Counter Treatments

• Benzocaine gels (Orajel, Anbesol) — numbs the area for temporary pain relief
• Hydrogen peroxide rinse — dilute to half strength, use as a mouth rinse to keep the sore clean
• Milk of magnesia — dab on the sore 3–4 times daily to coat and protect it
• OTC canker sore patches — adhesive patches that cover and protect the ulcer
• Debacterol — cauterizing agent available by prescription, can reduce healing time to 1 week

Home Remedies

• Salt water rinse — dissolve 1 teaspoon of salt in 8 oz of warm water, rinse for 30 seconds, 3–4 times daily
• Baking soda rinse — 1 teaspoon in 8 oz of water, helps neutralize acid and reduce inflammation
• Honey — apply directly to the sore; studies show medical-grade honey can reduce pain and speed healing
• Ice chips — hold against the sore for temporary numbing
• Chamomile tea bag — apply a wet, cooled tea bag to the sore (contains anti-inflammatory compounds)
• Avoid irritating foods — stay away from acidic, spicy, salty, and crunchy foods until healed

Prescription Treatments (for Major or Recurrent Sores)

• Fluocinonide gel (Lidex) — topical corticosteroid that reduces inflammation
• Triamcinolone acetonide paste (Kenalog in Orabase) — steroid paste applied to the sore
• Dexamethasone rinse — steroid mouth rinse for multiple sores
• Colchicine — for severe, frequently recurring canker sores
• Thalidomide — reserved for severe cases in HIV/AIDS patients (strict prescribing rules)

How to Speed Up Healing

• Start treatment at the first sign of tingling (before the ulcer fully forms)
• Use an SLS-free toothpaste (SLS can irritate and prolong sores)
• Avoid touching or irritating the sore
• Eat soft, bland foods
• Maintain good oral hygiene with gentle brushing
• Take a multivitamin if deficiencies are suspected (B12, iron, zinc, folate)
• Manage stress through exercise, sleep, and relaxation techniques

When to See a Doctor or Dentist

• Canker sores larger than 1 cm
• Sores that last more than 3 weeks
• Sores that are extremely painful and unresponsive to OTC treatment
• Frequent recurrence (more than 3 times per year)
• High fever accompanying the sores
• Difficulty eating or drinking due to pain
• Sores spreading or getting worse despite treatment
• Sores appearing outside the mouth (may be cold sores or another condition)

Recurrent canker sores may warrant blood tests to check for nutritional deficiencies, celiac disease, or immune system disorders.