Whether you call it a cold sore or a fever blister, oral herpes is a common infection of the mouth area that is caused by herpes simplex virus type 1 (HSV-1). Fifty percent to 80 percent of U.S. adults have oral herpes. According to the National Institutes of Health, about 90 percent of adults have been exposed to the virus by age 50.

Once infected, a person will have herpes simplex virus for the rest of his or her life. When inactive, the virus lies dormant in a group of nerve cells. While some people never develop any symptoms from the virus, others will have periodic outbreaks of infections.

Causes of Oral Herpes

Oral herpesis spread most commonly from individuals with an active outbreak or sore. You can catch oral herpes by engaging in intimate or personal contact (e.g., kissing or oral sex) with someone who is infected.

Prevention of Oral Herpes

Since oral herpes is spread through direct, physical contact, the best method of prevention is to avoid physical contact with a person’s herpes sores when they are having an outbreak.

Oral Herpes Symptoms

The initial (primary) infection of oral herpes is usually the worst. It may cause severe, flu-like symptoms, including swollen lymph nodes and headache. However, some people have no symptoms at all. During the initial infection, sores can occur on and around the lips and throughout the mouth. 

Recurring infections tend to be much milder, and the sores usually erupt on the edges of the lips. Some people never have any additional outbreaks beyond the initial infection. The following are the most common signs and symptoms of a recurring oral herpes simplex virus infection.

• Initial redness, swelling, heat/pain or itching may develop in the area where the infection will erupt.

• Painful, fluid-filled blisters may appear on the lips or under the nose. The blisters and fluid are highly contagious.

• The blisters will leak fluid and become sores.

• After about four to six days, the sores will start to crust over and heal.

The signs and symptoms of an oral herpes outbreak may look like other conditions or medical problems. Always consult your health care provider for an accurate diagnosis.

Diagnosing Oral Herpes

Since oral herpes can be confused with many other infections, including allergic reactions, a virus culture (PCR), blood test or biopsy are the only ways to confirm your diagnosis. However, your health care provider may also diagnose your condition based on the location and appearance of the blisters.

Recurrence of Oral Herpes

Although the specific triggers that cause oral herpes to recur are unclear, several factors may play a role. These include:

• A recent fever

• Emotional stress

• Menstruation

• Physical injury 

• Prolonged or intense exposure to sunlight

• Surgery

While recurrent outbreaks are more common in the first year after the initial episode, they tend to lessen as the body builds antibodies to the virus.

Oral Herpes Treatment Options

Your health care provider will recommend treatment options based on your:

• Age

• Expected outcome

• Overall health and medical history

• Personal preference

• Tolerance for specific medicines, procedures or therapies

Your specific treatment plan may involve:

• Keeping the infected area clean and dry

• Taking antiviral oral medications, such as acyclovir, famciclovir and valacyclovir (these medications are traditionally the most effective)

• Applying antiviral topical ointments, such as acyclovir and penciclovir

• Using over-the-counter topical anesthetics or anti-inflammatory agents to alleviate symptoms