Canker sores and cold sores

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What is it

These very common sores are often confused because they both usually occur in or around the mouth. But there are crucial differences in appearance, causes, and specific locations.

Canker sores have bothered humanity since ancient times. Hippocrates coined the medical term for them aphthous stomatitis in the fourth century BC. These craterlike lesions can occur on or under the tongue or inside the cheek. They have not been proved to have a viral origin, nor are they known to be contagious or a sign of disease.

Cold sores are tiny, unsightly, and often painful blisters that occur most frequently on the lips and adjacent skin, though occasionally on gums or the nose. Any reactivation of cold sores is usually, but not always, signaled 24 to 48 hours prior to an outbreak by an itching or tingling sensation in the lips. A small red area develops, followed by a blister or group of tiny blisters that fill with liquid.


Canker sores

  • Small white or yellow sores surrounded by a red area on the tongue or inside the lips or cheek.
  • A tingling sensation preceding the appearance of the sore.
  • Local pain when eating and talking, especially during the first two or three days.

Cold sores (also called fever blisters)

  • Tingly, itchy, fluid-filled blisters that commonly occur on the lips.
  • Local pain (usually), often preceding the blister by a few days.
  • Rupture of the blisters within hours, followed by crusting.

What causes it

No one is sure what causes canker sores, and there are no known remedies. Canker sores seem to be brought on by stress in some people; stress can also be a side effect. Heredity may play a role, and some women find that the sores recur with menstrual periods. Some people believe that irritation from such foods as chocolate, salted nuts, or potato chips can cause an out- break or that food allergies can cause the problem. There’s no proof, but it certainly won’t hurt to follow your hunches.

Another suspect is trauma the kind that comes from biting your tongue or the inside of your cheek, or from using a hard-bristled toothbrush, having a jagged tooth, rough dentures or being burned from hot food or liquids.

Cold sores, on the other hand, are caused by a virus called herpes simplex Type 1, which is different from the virus that causes genital herpes. The infection is contagious, but most people have already contracted the virus by early adulthood (though often with no symptoms). The virus lies dormant in the body until triggered by factors like a cold, fever, fatigue, sunlight, or emotional stress.

What if you do nothing

Painful and irritating as they are, canker sores usually go away in 5 to 15 days, with or without treatment.

Similarly, cold sores, although unsightly, pose no health threat and will clear up on their own within 7 to 10 days.

Home remedies

Conker sores

The Food and Drug Administration recently approved the first drug for canker sores, called amelxanox (Aphthasol). This prescription oral paste, intended only for canker sores, has been shown to ease pain and accelerate healing by a day or two. The following remedies may also help ease discomfort.

Ice it

Apply crushed ice to the sore. This will numb the pain and provide some relief.

Avoid spicy foods

Abrasive, acidic, and spicy food can irritate the sores.

Brush carefully

Using a soft brush will minimize irritation.

Try over-the-counter pain relief

If canker sores become very painful, ask your pharmacist to recommend an anesthetic drug or protective gel to reduce pain and inflammation.

Cold sores

A prescription antiviral medication, oral acyclovir (Zovirax), can help reduce the severity and duration of cold sores if taken as soon as you notice the early warning signs of itching and tingling. A prescription antiviral cream, penciclovir (Denavir), has also been approved for use as a medication that can speed healing of cold sores.

Other products (such as the amino acid lysine) have been suggested for treating cold sores, but there’s no evidence that they work. The following remedies won’t cure cold sores, but they may help reUeve symptoms.

Try ice

Applying an ice cube to the infected area may help relieve pain. Wrap an ice cube in a damp washcloth and keep it on the area for five minutes. Reapply it every hour.

Rinse with warm salted water

Rinse your mouth several times a day with a cup of warm water to which you’ve added a half teaspoon of salt.

Apply an ointment

An over-the-counter anesthetic ointment can help relieve pain.

Don’t pick

Do not squeeze, pick, or pinch a blister or a scab. A light coating of petroleum jelly to the scab will keep it from cracking and bleeding.

Wash carefully

This will help prevent infection. Avoid touching your eyes, genital area, or another person.


Canker sores

It’s not clear how to prevent canker sores, but the following steps can help.

Keep the mouth clean and healthy

Brush at least twice daily and floss regularly. And consider switching tooth cleansers: a recent study conducted in Norway suggested that a detergent found in most tooth pastes, sodium laurel sulfate, can aggravate canker sores. If you have recurrent sores, try switching to a tooth powder, baking soda, or other dentrifice without this ingredient.

Stop biting

Any mouth injury can get infected, so if you unconsciously bite the inside of your cheek, try to break the habit.

Stay away from anything that can hurt the lining of the mouth

This includes hard-bristled toothbrushes, toothpicks, and bones in meats.

Determine if specific foods trigger attacks

Avoid those foods that seem to cause problems.

Cold sores

Use sunblock

Outbreaks due to sun exposure can be prevented by applying sunscreen with a sun protection factor (SPF) of 15 on the lips before going outside and reapplying it frequently during the day.

Avoid touching the blisters

Touching the blisters and then other people is a possible way of spreading the virus. Kissing is one of the most common ways this transmission occurs.

Don’t share

During an outbreak, don’t lend personal items such as towels, razors, cups, or toothbrushes.

Consider medication

If you get frequent out- breaks, speak with your physician about taking low doses of the antiviral drug acyclovir.

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