Canker sores are small sores that happen inside the cheeks and lips, at the base
of the gums, and on or under the tongue.
Canker sores are different from cold
sores (fever blisters), which are caused by a virus and found outside the mouth
around the lips, on the cheeks or chin, or inside the nostrils. Cold sores are contagious,
but canker sores are not.
What Causes Canker Sores?
No one knows exactly what causes canker sores, also known as aphthous ulcers.
Many factors are thought to put a person at risk for them. Diet may play a part. People
whose diets are low in folic acid, vitamin B12, and iron seem to develop canker sores
more often, as do people with food
Mouth injuries (like biting the inside of the lip or even brushing too hard and
damaging the delicate lining inside the mouth) also seem to bring on canker sores.
Sodium lauryl sulfate (SLS), an ingredient in many toothpastes and mouthwashes, has
been linked to canker sores, and sometimes the sores can be a sign of an immune system
Even emotional stress could be a factor. One study of college students showed that
they had more canker sores during stressful periods, such as around exam time.
Who Gets Canker Sores?
About 1 in 5 people regularly get bothersome canker sores, which can make eating,
drinking, and even brushing teeth a real pain. Young people in their teens and early
twenties seem to get them most often, and women are twice as likely to develop them
as men. Some girls and women find that they get canker sores at the start of their
Although canker sores aren't contagious, the tendency to have outbreaks of canker
sores can run in a family.
What Are the Signs and Symptoms of Canker Sores?
Canker sores usually appear as round, painful open sores that have a white or yellowish
coating and a red "halo" around them. Most are small (¼ inch, or 6 millimeters
across) and shallow, but occasionally can be larger and deeper.
Most often, canker sores pop up alone, but they can appear in small clusters. Sometimes
an area will tingle or burn before a canker sore actually develops.
It takes about 2 weeks for canker sores to heal. During this time, the sores can
be painful, although the first 3 to 4 days are usually the worst. Unless they are
very large or deep, they usually heal without scarring.
How Are Canker Sores Diagnosed?
Just because canker sores are fairly common doesn't mean they should be ignored.
If your child has canker sores that last longer than 2 weeks or can't eat or drink
because of the pain, call your doctor. Also call if the sores appear more than two
or three times a year.
Usually, no tests are needed to diagnose canker sores, as doctors can identify
them based on medicalhistory and physical exam alone.
If your child gets canker sores a lot or they're severe, the doctor may want to
do tests to look for possible nutritional deficiencies (which can be corrected with
dietary changes or prescription vitamin supplements), immune system deficiencies,
and food or other allergies.
How Are Canker Sores Treated?
Most canker sores will heal on their own in a few days to a couple of weeks. If
they're painful, you can give your child an over-the-counter pain reliever like ibuprofen or acetaminophen.
If a sore doesn't get better after a few weeks or sores keeps coming back, see
a doctor or dentist. He or she may prescribe a topical medicine, special mouthwash,
or home remedy to help heal the sores.
For medicines that are applied directly to the sore, first blot the area dry with
a tissue. Use a cotton swab to apply a small amount of the medicine, and make sure
your child doesn't eat or drink for at least 30 minutes to make sure that it isn't
How Can I Help My Child Feel Better?
To help make canker sores less painful and keep them from coming back, encourage
your child to:
avoid eating abrasive foods, such as potato chips and nuts, which can irritate
gums and other delicate mouth tissues
try brushing and rinsing with toothpastes and mouthwashes that don't contain SLS
use only soft-bristle toothbrushes and be careful not to brush too hard
avoid any foods he or she is allergic to
avoid spicy, salty, and acidic foods (such as lemons and tomatoes), which can
irritate tender mouth sores