Oral Herpes vs. Canker Sores
- Cancer sores are not contagious.
- Canker sores are not the same thing as cold sores. Cold sores ("fever blisters") occur on the outer lip, whereas canker sores are found inside the mouth.
Oral herpes is a viral infection mainly of the mouth area and lips caused by a specific type of the herpes simplex virus. Oral herpes is also termed HSV-1, type 1 herpes simplex virus, or herpes labialis. The virus causes painful sores on the upper and lower lips, gums, tongue, roof of the mouth, inside the cheeks or nose, and sometimes on the face, chin, and neck. Infrequently, it may cause genital lesions. It also can cause symptoms such as swollen lymph nodes, fever, and muscle aches. People commonly refer to the infection as "cold sores."
Canker sores are sometimes thought to be caused by HSV, but this is not true. Canker sores occur only inside the mouth, on the tongue, and on the soft palate (roof of mouth), not on skin surfaces. Although they reoccur, they are not contagious, usually are self-limiting, and have almost no complications. Canker sores are caused by substances that irritate the lining of the mouth.
There are two types of herpes simplex viruses (HSV), they are termed HSV-1 and HSV-2. These two viruses have distinctly different DNA, and both cause oral and genital lesions. However, HSV-1 causes about 80% of all oral lesions and only about 20% of genital lesions while HSV-2 causes the reverse (about 80% genital and 20% oral). Studies also suggest that in adolescents, up to 40% of genital herpes is caused by HSV-1 because of reported increased oral/genital contact (transmission by oral sex).
Oral herpes (HSV-1) infection (or exposure without noticeable infection) is common. About 65% of the U.S. population has detectable antibodies to HSV-1 by age 40. This article will focus on HSV-1, or oral herpes, not on HSV-2, also commonly known as genital herpes. Genital herpes is considered to be a sexually transmitted disease (STD). In addition, HSV-2 virus should not be confused with human papillomavirus (HPV), the cause of genital warts, and some cervical and other cancer types.
Herpes simplex virus (HSV) is a DNA virus that causes sores in and around the mouth. Two herpes subtypes may cause these sores.
These herpes viruses enter the body through small cuts, abrasions, or breaks in the skin or mucous membranes. The incubation period for herpes simplex infections is about three to six days. Transmission (spread) of the virus is person to person and more likely to occur if blisters or lesions are present. The majority enter after an uninfected person has direct contact with someone carrying the virus (either with or without noticeable lesions). Simply touching an infected person is often the way children get exposed. Adolescents and adults frequently get exposed by skin contact but may get their first exposure by kissing or sexual contact (oral and/or genital contact), especially for HSV-2. Statistical studies suggest that about 80%-90% of people in the U.S. have been exposed to HSV-1 and about 30% have been exposed to HSV-2. Usually, the contagious period continues until lesions heal. Some people (estimated from 30%-50%) occasionally shed herpes virus while having few or no associated symptoms or signs.
Oral lesions (and genital lesions) can reoccur. This happens because the HSV viruses are still alive but exist in nerve cells in a quiet, inactive (dormant) state. Occasionally, conditions in the body (see stage 3 above) allow the HSV to actively multiply, resulting in a new crop of lesions.
The HSV viruses multiply in the human cell by overtaking and utilizing most of the human cells functions. One of the HSV steps in multiplication is to take control of the human cell's nucleus and alter its structure. The altered nucleus (enlarged and lobulated or multinucleated) is what actually is used to help diagnose herpes simplex infections by microscopic examination. The reason sores appear is because as they mature the many HSV particles rupture the human cell's membrane as they break out of the cell.
Transmission of HSV-1 occurs by direct exposure to saliva or droplets formed in the breath of infected individuals. In addition, skin contact with the lesions on an infected individual can spread the disease to another individual. Although close personal contact is usually required for transmission of the virus, it is possible to transmit HSV-1 when people share toothbrushes, drinking glasses, or eating utensils.
Unfortunately, everyone is at risk to get HSV-1 infection. The majority of children between 6 months to 3 years of age are exposed to HSV-1 simply by contact with other humans. By 14-49 years of age, about 60% of the population has been infected, and by age 60, about 80%-85% of the population has been infected with HSV-1.
Signs and symptoms of dehydration usually warrant going to a hospital's emergency department. Infants, especially under 6 weeks of age or if the infant appears to slow urine output or decrease fluid intake, should be evaluated by their pediatrician or in an emergency center if oral sores appear. Individuals with immune suppression (for example, patients undergoing chemotherapy, HIV patients, or cancer patients) should contact their doctors if they suspect a HSV-1 infection.
A doctor will base a presumptive diagnosis on information provided by the patient and on the physical examination. The characteristic appearance of the herpes sores leaves little doubt about the diagnosis, so the typical appearance of the sores is key to the diagnosis. This appearance helps distinguish oral herpes from oral thrush, shingles, gonorrhea, and syphilis. In addition, chapped or sunburned lips can resemble oral herpes, but the tissue stain (Tzanck smear, see below) shows no virus-induced cell changes. Further testing is usually not necessary but is sometimes done.
If a definitive diagnosis is needed, because, for example, the infection involves other organ systems, the doctor may conduct laboratory tests listed below:
For mild infections, self-care may be adequate for treatment. Other treatments termed "home remedies" are not considered cures but can ease or hasten recovery. These remedies include aloe vera gel, cornstarch paste, and tea or mint leaves. A cool compress may reduce pain. There is no cure for the infection. People with severe infection symptoms, especially children, should be evaluated by a medical caregiver.
Treatment includes medication for fever (see above, anti-inflammatory drugs) and taking plenty of fluids.
Mild uncomplicated eruptions of herpes simplex require no treatment. Severe infection may require treatment with an antiviral agent. Oral antiviral drugs include
These drugs may stop viral replication in the skin but do not eliminate HSV from the body or prevent later outbreaks (HSV reactivation). These drugs are used more frequently with HSV-2 infections. Most investigators suggest consulting an infectious-disease expert when HSV-infected people need hospitalization. Research findings suggest laser treatments may speed healing and lengthen the time before any sores reappear.
Some patients will not require a physician to treat them. However, pediatricians, primary-care doctors, emergency-medicine doctors, dentists, dermatologists, and occasionally infectious-disease doctors treat HSV-1 infections.
Drink plenty of fluids.
To reduce the chance of acquiring HSV-1, avoid touching saliva, skin, or mucous membranes of people who have HSV-1 lesions. Prevention of genital HSV may be accomplished by latex condoms, but protection is never 100%. Spermicides do not protect against HSV. Some clinicians recommend using dental dams (small latex squares) during oral sex, but like condoms, they are not 100% protective.
An experimental vaccine against HSV-1 is being tested in England that may be marketed in the near future. Currently, there is no cure for HSV-1.
The sores and symptoms of oral herpes usually completely disappear in two to three weeks with no scarring. However, the sores may reappear under certain stressful situations. Rarely, some complications develop in a few individuals: