Canker sores (aphthous ulcers)
Canker sores are small, shallow, painful ulcers inside the mouth — on the inside of the cheeks or lips, the sides of the tongue, or the floor of the mouth. They’re not contagious and aren’t the same as cold sores (which appear on the lips). There’s no single cause, but minor injury (a bite or sharp tooth), stress, certain foods, and some medical conditions can trigger them. Most heal on their own within 7–14 days; treatment is mainly about easing the pain and protecting the sore while it heals.
Self-care products available in our shop
- Numbing gels and oral anesthetics (e.g., benzocaine products like Orajel)
- Protective oral pastes that cover and shield the sore
- SLS-free toothpaste (sodium lauryl sulfate can worsen sores)
- Antiseptic / soothing mouth rinses (alcohol-free)
- Acetaminophen (Tylenol) for pain
- A simple salt-water rinse (½–1 tsp salt in a cup of warm water, several times daily, spit out) also soothes and keeps the area clean.
Treatments our pharmacist can prescribe
For your information only: in Ontario, our pharmacist can assess this condition and, when appropriate, prescribe the medication listed below. This information is provided for educational purposes — it is not an offer to sell. This is a prescription treatment that requires a pharmacist assessment, and the right option is chosen for you.
Anti-inflammatory agents: Triamcinolone (in an oral paste/dental base, e.g., Oracort)
When to seek further care: See a health-care provider if the sore lasts longer than 14 days, is larger than 1 cm, is on the roof of your mouth or gums, keeps coming back or multiplying, or comes with fever, joint pain, eye irritation, or diarrhea.