Mouth ulcers and cold sores are easy to mix up. Both are painful, appear in or around the mouth and tend to come back. Beyond that, they have little in common. They have different causes and look different, and what helps one does nothing for the other. Before you choose something for the pain, check which one you have.
What is a mouth ulcer?
A mouth ulcer, also called a canker sore or aphthous ulcer, is a small, painful sore inside the mouth. It can appear on the inside of the cheeks or lips, on or under the tongue, or at the base of the gums. It is usually round or oval, with a white or yellowish centre and a red edge.
Mouth ulcers are not contagious, so you cannot catch one from someone else or pass one on. They are often set off by biting the inside of the cheek, rubbing from braces or dentures, sharp or hot food, stress and tiredness, hormonal changes or low levels of certain nutrients. Many people also get them now and then for no clear reason.
Most mouth ulcers heal on their own within a week or two. The hard part is the pain until then, because eating, drinking and even talking can hurt.
What is a cold sore?
Cold sores are caused by a virus, the herpes simplex virus. Most people pick it up in childhood. The virus then stays in the body for life and causes a sore from time to time.
Cold sores appear on or around the lips, not inside the mouth. They usually start with tingling, itching or burning. Within a day or two, small fluid-filled blisters appear, which then burst and crust over into a scab. Most cold sores clear up within about ten days.
Unlike mouth ulcers, cold sores are contagious, from the first tingling until they have fully healed. The virus spreads through close contact such as kissing. While you have a cold sore, wash your hands after touching it, avoid kissing and keep away from newborn babies.
The differences at a glance
| Mouth ulcer (canker sore) | Cold sore | |
|---|---|---|
| Where | Inside the mouth | On or around the lips |
| What it looks like | Round sore, white or yellow centre, red edge | Small fluid-filled blisters that crust over |
| Cause | Injury, irritation and other triggers; not a virus | Herpes simplex virus |
| Contagious? | No | Yes, until fully healed |
| Usual healing time | One to two weeks | About ten days |
Looking after a cold sore
A pharmacist can suggest an antiviral cream, or patches that cover the sore while it heals. Start the cream as soon as the tingling begins. Do not touch or pick the sore, and dab the cream on gently rather than rubbing it in.
UlcerMagic is not for cold sores. Do not use it on cold sores, on blisters in the mouth or on sores on the lips.
Where UlcerMagic fits
UlcerMagic is for mouth ulcers inside the mouth. It is a liquid that you apply to the ulcer with a cotton swab, and each ulcer is treated once only. It relieves the pain in seconds and forms a protective layer over the ulcer while the mouth heals naturally.
It is for adults and children aged 12 and over. Do not use it during pregnancy or if you are allergic to sulphur. The how-to-use guide sets out the four steps and every caution printed on the pack.
When to see a doctor or dentist
Whichever kind of sore you have, see a doctor or dentist if:
- a mouth ulcer lasts more than 3 weeks;
- ulcers keep coming back, or one looks different from those you have had before (for example, it is larger, or near the back of the throat);
- an ulcer bleeds, or becomes more painful and red;
- a cold sore has not started to heal within 10 days, or is very large or painful;
- you also have a fever, feel unwell or have sores elsewhere on the body.
Sources
- NHS. Mouth ulcers
- NHS. Cold sores
- Mayo Clinic. Canker sore: symptoms and causes