Cold sore or canker sore? How to tell them apart

Cold sore:

• On or around the outside of the lips
• Often starts with itching, burning or tingling
• Small blisters filled with fluid that break open, then crust over
• Caused by the herpes simplex virus, and spreads to others

Canker sore:

• Inside the mouth: on the cheeks, inner lips, tongue or gums
• A round, painful open sore that is white or yellow with a red edge
• Not caused by a virus that spreads, so it is not contagious

Cold sores usually show up outside the mouth, but they can also show up inside it, most often on the gums or the roof of the mouth. If you are not sure which one you have, a doctor can help tell them apart.

Cold sores most often heal on their own in 1 to 2 weeks, but they can come back. Sun, stress, a fever or hormone changes can set them off.

Antiviral medicine can help a cold sore heal sooner. It works best if you start it at the first tingle, before blisters form. People who get cold sores often may take medicine every day to prevent them.

• Hold ice or a warm, wet cloth on the sore to ease pain.
• Avoid hot drinks, spicy or salty foods and citrus.
• Use lip balm with sunblock before you go outside.

• Do not kiss anyone while you have a sore.
• Do not share cups, straws, forks, spoons, lip balm or towels.
• Do not have oral sex while you have a sore. The virus can spread to the genitals.
• Wash your hands after touching the sore.

Most canker sores go away on their own. The pain often eases in 7 to 10 days. A sore can take 1 to 3 weeks to heal fully.

• Avoid hot or spicy foods.
• Rinse with salt water or a mild mouthwash without alcohol.
• Try a store-bought numbing gel or rinse for short-term relief.

Biting your cheek, brushing too hard, stress, and low iron, folic acid or vitamin B12 can set off canker sores.

• A sore near your eye, or eye pain or redness with a cold sore
• A weakened immune system from an illness or medicine
• A mouth sore that has not healed after 2 weeks
• Fever, a rash or diarrhea along with mouth sores
• Sores on the genitals along with mouth sores
• A white patch in the mouth that does not wipe off
• Your first cold sore ever

Get care the same day if mouth sores hurt so much that you cannot eat or drink. You could get dehydrated.

Herpes in the eye can harm your vision, so get eye symptoms checked right away.

Go to the emergency room for a fever with confusion or a bad headache, a seizure, new numbness or weakness in the face, arms or legs, or new tingling in an arm or leg. These can be signs of a serious problem, such as an infection of the brain.

If you are in Virginia or West Virginia, you can start a visit online at any time. Our cold sore visit is for adults and children 4 and older (with a parent or legal guardian) who have had cold sores before and have one now that looks and feels the same. It is not the right fit if you have:

• A first-ever cold sore
• Eye pain or redness, or a sore near the eye
• A weakened immune system, or medicine that weakens it
• Kidney disease
• Trouble swallowing, many sores in the mouth, or trouble drinking enough
• Blisters that spread past your usual cold sore area, or bad swelling of the face
• A high fever
• A lip sore that has not healed in 3 weeks
• Any of the emergency signs above

Our canker sore visit is for adults and children 4 and older (with a parent or legal guardian) with classic canker sores that keep coming back. It is not the right fit if you have:

• A single sore that has not healed in 2 weeks
• Sores on the genitals, or a red, painful or swollen eye, along with mouth sores
• Diarrhea, belly pain or weight loss you cannot explain, along with mouth sores
• A weakened immune system
• Mouth pain so bad you cannot eat or drink
• A first bad outbreak after age 40
• A white patch in the mouth, whether or not it wipes off

You answer a few questions and send a clear photo. There is no video call. A board-certified physician reviews your answers. If medicine is right for you, the doctor can send a prescription to your pharmacy. If you need to be seen in person, the doctor will tell you.

Visits start at $59. You see the price before you pay, and you do not need insurance.