What are cold sores and canker sores?


Canker sores, also known as apthous ulcers, are crater-like sores that usually appear individually on your child's tongue, gums, or on the inside of his/her cheeks. They are painful and make eating certain foods very uncomfortable. Canker sores usually go away by themselves in about three weeks without any treatment. There are numerous over the counter forms of canker sore relief products such as Orabase topical anesthesia that can help alleviate your child's discomfort. Canker sores are not contagious like cold sores and are not spread to other people. The exact cause of canker sores is unknown, but may be due to many reasons such as stress, trauma, viruses, allergies, trauma, or nutritional deficiencies.


Cold sores, also known as fever blisters, are small, fluid-filled blisters that crop up on or near your child's lips. They are usually caused by the herpes simplex virus. They can appear individually or in clusters.

How did my child get the virus? The most common way to catch a cold sore is from a kiss. Other ways are by sharing a cup, spoon, or fork. The person who passes the virus to your child may not have a visible sore or any symptoms at all, but has the virus in his or her saliva. Most people get the herpes simplex virus sometime during childhood. During the first bout, called primary herpes, your child may have severe mouth soreness, gum inflammation, perhaps a fever, swollen lymph nodes, and a sore throat. These primary symptoms may be very severe or very mild. In fact, you may not even notice them. Your child will get better in about seven to ten days, but the virus will stay in his body for life. In some people, it lies dormant and never acts up. In others, it periodically flares up and the cold sores appear. These flare-ups are called secondary herpes. Stress, fever, and sun exposure, but not contact with a cold sore seems to trigger outbreaks. During these secondary flare-ups, your child probably won't have swelling of his gums or lymph nodes or a fever or sore throat, but he will have the telltale blistering on or near his lips.

Are cold sores ever dangerous? Cold sores themselves aren't dangerous, but it’s possible for the virus to spread to other parts of the body. When it spreads to the eyes, for example, it's called ocular herpes, which is a serious eye infection. If your child develops a sore on his eyelid or the surface of his eye, call his doctor right away. Your child may need antiviral drugs to keep the infection from scarring his cornea. In rare cases, ocular herpes can weaken vision and even cause blindness. Try to keep your child from touching his eyes when he has a cold sore. In fact to keep him from spreading the infection, have him wash his hands regularly and try to keep him from picking at the cold sore. You may want to put mittens or socks on his hands while he sleeps.

How can I prevent cold sores? If you have a cold sore, you should avoid kissing your child until the cold sore goes away. Remember, one peck with an infected lip is all it takes to pass on the virus. You'll also want to avoid sharing cups and eating utensils while you have a cold sore. You'll want to protect your child from the sun as well, since exposure to sunlight can trigger an outbreak once a child has the virus. If you venture outside on a sunny day, put a brimmed hat on your child to protect him from the sun’s rays. You can also put lip balm on him for protection.


Doctor Wang, Doctor Perea-Corkish, Doctor Gerodias and the other Doctors of Discovery Pediatric Dentistry make no warranties, expressed or implied, as to any results to be obtained from use of the information on this page. We cannot diagnose or treat patients over the Internet. Information on this site is for educational purposes only. You should not rely on this information as a substitute for personal, medical, and/or dental attention or diagnosis. Without all available information about a patient, it is impossible to make a diagnosis. Help and answers are in the form of general ideas. Only you, your dentist, and other necessary and qualified health care providers can make an appropriate treatment decision in an emergency or for everyday care and dental treatment.

Read our full disclaimer