Skip Ribbon Commands
Skip to main content
Health Issues
Text Size
Facebook Twitter Google + Pinterest

Herpes Simplex Virus (Cold Sores)

Herpes simplex viruses (HSVs) cause raised and oozing sores or blisters. When these sores erupt on or close to the lips or inside the mouth, they are commonly called cold sores or fever blisters. In most cases, these facial sores are caused by the HSV type 1 (HSV-1) strain. Herpes infections can also affect the genitals. These sores are usually caused by another herpes strain, HSV type 2 (HSV-2). However, both strains of the virus can cause sores in any part of the body. Herpes simplex viruses can involve the brain and its lining to cause encephalitis and meningitis. In the newborn, herpes viruses cause severe infections along with brain, lung, and liver disease as well as skin and eye sores.

The herpes virus is very contagious. It can be spread from one child to another or from parent to child through direct contact with a herpes sore or by contact with the saliva of someone with the infection (eg, through kissing). In athletes, especially wrestlers and rugby players, the virus can be transmitted during the physical contact of competitive events. The genital form of the infection is a sexually transmitted disease (STD). Babies can be infected during the birth process. The incubation period of these infections averages 6 to 8 days.

Signs and Symptoms

When your child develops a herpes infection for the first time (primary HSV infection), mouth sores, fever, and swollen, tender lymph glands are the most common symptoms, usually seen after swelling and reddening of the gums. These sores slowly heal over 7 to 14 days. During a herpes flare-up, children develop 1 or 2 sores around the mouth. In some youngsters, however, the symptoms are so mild that no one is even aware that an infection is present.

After your child’s initial herpes infection occurs and has run its course, the virus itself will remain in the nerve cells of his body in an inactive or dormant (latent) form. He will be a carrier of the herpes virus for life. From time to time, the virus may become active again (sometimes in response to cold, heat, fever, fatigue, stress, or exposure to sunlight), causing a return of a cold sore (secondary HSV infection). These outbreaks often begin with a tingling or itching sensation in the area where the sores are about to break out. The sores and blisters often become crusty before healing.

When the genitals are affected, the herpes lesions are found on the penis, vagina, cervix, vulva, buttocks, or other nearby parts of the body. As with the oral sores, someone with genital herpes may have repeated outbreaks over a lifetime. When an HSV infection occurs in newborns, it tends to develop in the first few weeks of life. The baby becomes infected while passing through the birth canal. The virus attacks the liver, lungs, and central nervous system as well as the skin, eyes, and mouth. This is a life-threatening infection that can lead to permanent brain damage or even death.

Herpes simplex viruses also cause encephalitis, an infection of the brain. Children with encephalitis have fever, headache, irritability, and confusion. Seizures are common. Herpes simplex type 2 often causes a mild form of meningitis that does not cause long-term problems or brain damage.

What You Can Do

Serious herpes infections, such as those affecting newborns or the brain, will require hospitalization and intensive care. Superficial infections of the mouth can usually be treated at home. After a few days, most cold sores will go away on their own. During the outbreak, prevent your child from scratching or picking at the sores.

When your child has a cold sore, make him as comfortable as possible. Avoid foods and drinks that irritate the sores. Help prevent dehydration by giving him extra fluids. Apple juice will cause less irritation than drinks such as orange juice or lemonade that are more acidic.

When To Call Your Pediatrician

If your child develops signs and symptoms of a first herpes infection, contact your pediatrician. If your youngster has fever, swollen glands, or trouble eating because of mouth sores, your pediatrician may suggest an office visit. Watch your child for dehydration and call your pediatrician if you are concerned about this. Keep in mind that most cases of herpes do not cause serious illness. If your teenager develops genital herpes, contact your pediatrician to arrange for a visit. An antiviral medicine can speed healing.

If your newborn develops a rash, fever, or irritation of the eyelids or eyes in the first month of life, contact your pediatrician immediately. The doctor will probably want to examine the baby in the office or emergency department. If your infant, child, or teenager has a seizure or fever, headache, and confusion, contact your pediatrician without delay.

How Is The Diagnosis Made?

Your doctor will usually diagnose a herpes infection through visual examination of the sores. Laboratory tests are available and can be used to confirm the diagnosis, although they are not always necessary. In these tests, a tissue scraping of the sores may be examined under the microscope, or a blood test is given. In the case of brain infection, an electroencephalogram (EEG) and imaging studies may be done to help with the diagnosis. In addition, a lumbar puncture (spinal tap) will be done to examine the spinal fluid for signs of infection. Newborns will have a variety of tests performed to look for evidence of viral infection of the brain, lungs, and other organs.


If your child complains of pain and discomfort related to the sores during a herpes outbreak, talk to your pediatrician about giving him acetaminophen. Your pediatrician can also prescribe a number of antiviral medicines, such as acyclovir, for HSV infections. These prescription drugs keep the virus from multiplying and, if given early, reduce symptoms and heal the sores more rapidly. Sometimes special numbing liquid, prescribed by your pediatrician, can be applied to the mouth sores to relieve pain. However, most children with oral herpes outbreaks are not given these medicines because they recover quickly on their own.

Antiviral drugs can be lifesaving for newborns with the infection, as well as for older children with more severe infections such as in and around the brain and children whose immune systems are weakened because of an HIV infection or cancer treatments. Antiviral drugs are used more frequently for genital herpes and may be prescribed for the first genital outbreak.

Antiviral drugs can be given continuously to prevent outbreaks from returning. However, there is limited information about the success of long-term therapy in children. In adults with frequent genital herpes outbreaks, an antiviral is given continuously for a year to decrease the outbreaks.

What Is The Prognosis?

While most cold sores are uncomfortable and may be cosmetically unattractive, they are usually not a serious problem. Most outbreaks run their course in several days and have no lasting effects.

When herpes infections affect newborns, they can be more dangerous. They can cause serious illness and sometimes death, even when appropriate medicines are given. In older children, a form of encephalitis can develop and must be treated effectively to avoid long-term neurologic problems such as seizures and weakness. The mild form of meningitis caused by HSV-2 infections usually goes away in a few days to a week.


To prevent the spread of HSV, your child should avoid contact with the sores of someone with an outbreak. Remember that many people will have the virus in their saliva even when sores are not present. Do not allow your child to share eating utensils or drinking glasses with others. In most cases, your youngster can attend school with an active infection, but your pediatrician may suggest keeping him home if he has a primary outbreak.

Sexually active teenagers should use a latex condom during every sexual experience.

Last Updated
Immunizations & Infectious Diseases: An Informed Parent's Guide (Copyright © 2006 American Academy of Pediatrics)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
Facebook Twitter Google + Pinterest