Cold Sores (Labial Herpes): Causes, Treatment, Symptoms & Contagious

Herpes simplex infections (nongenital cold sores) facts

Picture of cold sores (oral herpes, herpes labialis) on the lips (fever blisters, HSV 1, or herpes simplex infection type 1)

Herpes simplex virus (HSV) can cause infections that affect the mouth, face, genitals, skin, buttocks, and anal area. It is one of the most common chronic viral infections in humans. The prevalence of HSV-1 (oral herpes) infection is 67% of adults worldwide and is higher than the prevalence of HSV-2 (genital herpes).
Of the two herpes simplex viruses (HSV-1 and HSV-2), cold sores are most commonly caused by HSV-1.
The virus resides deep in the nerve roots and may reactivate at a later time, causing the same symptoms and signs in the same location.
Cold sores (herpes labialis) usually go away within 1-2 weeks, but they can be treated with antiviral medications, like acyclovir or topical antiviral creams such as docosanol (Abreva), to reduce pain and shorten healing time.

Treatment of Cold Sores

Currently, there are no cures or vaccines for cold sores caused by the herpes simplex virus (HSV). Frequent hand washing will help reduce the spread of the virus to other parts of the body or to other people. Also, applying cool, moist compresses to the lesion may decrease pain and keep the lesion from drying and cracking.

What are herpes simplex infections?

When herpes simplex flare-ups appear in their most common location, around the mouth, chin, and upper lip, people often refer to them as "cold sores" or "fever blisters.

Herpes simplex virus (HSV) can cause infections that affect the mouth, face, genitals, skin, buttocks, and anal area. This article will concentrate on nongenital herpes.

Many people acquire the virus and have no symptoms or signs.
For others, painful fluid-filled small blisters appear near the area where the virus entered the body.
Typically, the blisters heal completely but may reappear at some point in the future.
In between attacks, the virus resides deep in the roots of the nerves of the involved area.
When herpes simplex flare-ups appear in their most common location, around the mouth, chin, and upper lip, people often refer to them as "cold sores" or "fever blisters."
Oral herpes may cause ulcers, fluid-filled blisters, or sores anywhere inside the mouth, including the gums and the tongue.
It may also cause sores inside the nose and around the nostrils. Herpes may also affect the eye.

What is primary oral herpes?

Primary herpes refers to the initial outbreak of symptoms after infection, often presenting with painful sores on the lips, gums, and mouth.

In some people, primary herpes is associated with fever, swollen lymph nodes, and bleeding gums, together with painful ulcers around the mouth (gingivostomatitis) and sore throat. These signs and symptoms may last several days. Difficulty in eating and drinking may lead to dehydration. The sores heal completely in 2-6 weeks, usually without scarring. Virus can be recovered from the saliva for days after the lesions heal. Primary herpes usually occurs during childhood.

Not everyone has a severe primary attack when they are first infected with herpes. In most people, the virus infects the body without causing any symptoms. The process generates an antibody response, causing the immune system to produce antibodies against the herpes virus. This antibody response helps reduce recurrences and keep them mild. Antibodies also make it harder for the virus to get a foothold somewhere else in the body. However, it is possible to transfer the herpes virus to other parts of the body (autoinoculation).

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Cold Sores (Nongenital Herpes Simplex Infections)
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What causes cold sores?

Cold sores are caused by the herpes simplex virus (HSV).

There are two types of HSV, herpes simplex virus type 1 and type 2.

In general, HSV-1, also known as herpes labialis or oral herpes, causes infections above the waist, most commonly as "cold sores."
HSV-2 infections occur mainly below the waist, leading to genital herpes.

However, both types of HSV are capable of infecting the skin at any location on the body. Thus, the virus that usually causes oral herpes (HSV-1) can cause genital herpes as well as herpes on the hands and eye. The virus that causes genital herpes (HSV-2) can also cause oral herpes, although it almost exclusively infects the genital area. HSV-1 may cause genital herpes via self-inoculation from oral lesions, or via oral sex.

Herpes infections, no matter where they occur first, have a tendency to recur in more or less the same place. Such recurrences may happen often (for example, several times per year) or only occasionally. You would know that you have herpes if you have an outbreak or if a doctor performs a blood test to tell if you have been infected with it. Most adults have been infected with oral or genital herpes and never know it.

What makes herpes (cold sores) recur?

After infection, the virus enters the nerve cells and travels up the nerve until it comes to a place called a ganglion. There, it resides quietly in a stage that is referred to as "dormant" or "latent." At times, the virus can become active and start replicating again and travel down the nerve to the skin, causing a cold sore outbreak. The exact mechanism behind this is not clear, but it is known that some conditions seem to trigger recurrences, including

a fever, a cold, or the flu;
UV rays (sun exposure or a sunburn);
emotional or physical stress (such as an illness or surgery);
weakening of the immune system;
trauma to the involved area such as dental work; and
sometimes there is no apparent cause of the recurrence.

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What are the risk factors for herpes simplex infections?

Exposure to someone with cold sores increases the risk of getting oral herpes. HSV is most contagious when the person has mouth sores or blisters on the lips.

The virus can also be shed from saliva when there are no visible lesions. This is called "asymptomatic shedding."
Therefore, a person can be contagious without having a cold sore outbreak.
Direct contact with the virus, from kissing or sharing personal items, or skin-to-skin contact, will increase the chance of getting infected with HSV.
Abnormal areas of skin such as eczema may be especially prone to herpes infection.
Health care workers, such as dentists, dental hygienists, and respiratory therapists, are at risk of developing herpetic whitlow because of contact with people's mouths.
Medical conditions or treatments that weaken a person's immune system can increase the risk of severe complications from the virus. These include
- HIV,
- cancer,
- chemotherapy, and
- steroids.

Are cold sores contagious?

Oral herpes is contagious to others who do not have it.

How do cold sores spread?

The virus is spread from person to person by kissing, by close contact with herpes lesions, or from saliva even when sores are not present. Infected saliva is a common means of virus transmission. The contagious period is highest when people have active blisters or moist sores. Once the blisters have dried and crusted over (within a few days), the risk of contagion is significantly lessened. HSV can also be spread through personal items that are contaminated with the virus, such as lipstick, utensils, and razors. Despite popular myth, catching herpes (cold sores) from surfaces, towels, or washcloths is a very low risk, since the virus does not usually survive long on dry surfaces.

What is the incubation period for cold sores?

The time between infection and symptoms of primary oral herpes is anywhere from 2 days to 2 weeks.

What are the signs and symptoms of cold sores?

The hallmark symptom of herpes is tingling or a burning sensation before the appearance of the outbreak.

The classic sign of herpes is a cluster of blisters on a base of red skin.
The blisters look like a drop of water filled with clear liquid.
These blisters dry up rapidly and leave a crust or scab that lasts anywhere from a few days to a few weeks, depending on the severity of the infection.
This pattern has important implications for the many people who fear they have herpes but don't, If you are healthy and the rash lasts for weeks, it is unlikely to be herpes.

Herpes infections feel dry and crusty, and they may cause pain or itch. Some patients have a "prodrome," which is the occurrence of certain symptoms before the actual sores become fully evident. The prodrome to herpes infections typically involves flu-like symptoms and a burning or tingling sensation that precedes the appearance of blisters by a few hours or a day or two.

What does recurrent herpes look like?

Recurrent herpes occurs in the area where it first appeared, though most of the time, there are fewer blisters or a milder outbreak than the first time. Although the face is the most common site of infection, other areas of the body may be involved:

Labial herpes: This is the familiar cold sore that appears on the lip margins (labial refers to the lip). When labial herpes reappears, it usually occurs at the same location each time or a few millimeters away. L-lysine and other vitamin supplements have not been shown to speed healing or reduce outbreaks.
Herpetic whitlow: Sometimes, the herpes virus shows up on the fingers. This is especially common in dental and medical workers who have to put their fingers inside people's mouths, despite the use of gloves. In herpetic whitlow, the virus has entered the finger. Occasionally, the virus re-emerges and causes blister-like sores on the fingertip.
Wrestlers' herpes or herpes gladiatorum: Wrestlers or any athlete engaged in direct contact sports can contract herpes from an opponent who is shedding the virus. This form of herpes can appear anywhere over the body, but the face, neck, and arms are common locations. Unlike most other types of infection, lesions may occur at multiple sites.
Eczema herpeticum: This may occur in people (especially children) who have areas of eczema or atopic (allergic) dermatitis, which is very itchy. They may scratch and spread herpes to these areas if they have cold sores or other sources of active herpes infection (autoinoculation). The skin involved with eczema or allergic dermatitis is less able to fight viral infections, and herpes spread to this area may result in widespread sores.

In recurrent herpes, it often takes 7-10 days before the ulcers completely disappear and the skin returns to normal.

What other conditions can look like oral herpes (cold sores)?

There are many conditions that can be confused with herpes, including

scrapes,
razor burns,
pimples,
impetigo,
angular stomatitis (sores at the corners of the mouth), and
canker sores (aphthous ulcers).

What is angular stomatitis?

Angular stomatitis refers to inflammation, cracking, or irritation at the corners of the mouth. In contrast, herpes infections usually appear on the upper or lower lip margins, not in the corners. Angular stomatitis may be an initial sign of anemia or vitamin deficiency. It can also occur in people who wear dentures, whose saliva can accumulate and lead to the overgrowth of yeast.

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What are canker sores?

Canker sores, or aphthous ulcers, are ulcerations that occur inside the mouth along the mucosa. They are found on the inner cheeks and lower lip as well as on the tongue, palate, and the gums. Canker sores are round and very painful. They are gray in color with a distinct edge. They are not contagious and are caused by stress or trauma to the area. They are not related to herpes, although they be may confused with oral ulcers caused by herpes.

What types of doctors treat cold sores?

Most pediatricians and primary care providers are very familiar with cold sores and their treatment. Most cases do not need the services of a dermatologist (skin specialist). An infectious-disease specialist is often consulted in complicated cases, such as herpes encephalitis or herpes in a person with a weak immune system. The care of an ophthalmologist (eye specialist) is important in managing ocular herpes, or herpes keratitis.

What tests do health care professionals use to diagnose oral herpes?

The diagnosis of herpes (cold sores) is easily made based on the visual appearance of the lesions, and the best approach is to see a doctor at the first sign of a blister. If there is concern that the rash may not be herpes, a swab of blister fluid may be collected for viral culture or polymerase chain reaction (PCR) test. This is most useful in the first 48 hours before the blister has crusted over. If lesions resolve, then cultures are of no help, because there's nothing left to culture. Culture results take a minimum of 3-5 days.

PCR testing detects herpes DNA, but it is not as readily available as culture and is a very expensive test to do for simple cold sores.

Blood tests for herpes antibodies are not usually needed, since finding antibodies to herpes just means that the body has been exposed to this virus at some point in the past. It does not determine if the current lesion is due to herpes. They can be done, though, if the diagnosis is unclear or there is a specific reason to know for certain.

How long do cold sores last?

In primary herpes, the healing process usually takes 2-3 weeks, but skin pain can last for 1-6 weeks.

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What is the treatment for cold sores in children?

Treatment for children is similar to that in adults (other than being dosed by weight), except that famciclovir does not have an approved pediatric dose.

What home remedies and over-the-counter drugs are used for the treatment of cold sores?

Home remedies

Home remedies include applying a cool wet compress to the lesion to decrease pain and keep the lesion from drying and cracking. Applying compresses too often will cause more drying, however, so a moisturizing balm should be applied after the lesion is first softened with a wet compress. Lemon balm (Melissa officinalis) and L-lysine are popularly used as home remedies. While there is there is very limited data suggesting that these substances have antiviral properties, and not enough data to support recommendations, these remedies seem generally well tolerated for those who wish to try them at their own risk.

Natural treatment options provide pain relief and treat cold sores

Lemon balm, L-lysine supplements, citrus bioflavonoids, Lactobacillus acidophilus and bulgaricus, vitamin C, vitamin E oil, and vitamin B12 have also been considered in the potential treatment of herpes simplex virus, but there is no good clinical evidence to support these treatments. Lemon balm may have some anti-herpes properties, but it is impossible to tell if it is effective in affected people from the few laboratory experiments that have been published. L-lysine similarly has limited laboratory data suggesting antiviral properties and has been touted for reducing recurrence of herpes. Unfortunately, results in patients with cold sores have been highly variable; and there are no high quality studies suggesting benefit.

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What prescription drugs treat cold sores?

Prescription-strength topical medications: Treatment with topical acyclovir (Zovirax 5% cream) or penciclovir (Denavir 1% cream) will reduce healing time by approximately half a day and decrease pain associated with the lesion. Topical treatment is limited in its effectiveness because it has poor penetration to the site of replication of the virus and therefore is restricted in its healing ability. Acyclovir cream should be applied five times per day for 4 days, and penciclovir cream should be applied every two hours while awake for 4 days. A cream containing 5% acyclovir and a topical steroid (hydrocortisone) called Xerese is also available.

Oral prescription-strength medications: The current FDA-approved oral antiviral drugs used in the treatment of herpes simplex virus in adults are acyclovir, valacyclovir (Valtrex), and famciclovir (Famvir). These oral medications have been shown to decrease the duration of the outbreak, especially when started during the prodrome before the rash appears. Acyclovir, valacyclovir, and famciclovir are considered relatively safe and effective when used in pregnancy, although topical treatment would be preferred when appropriate. Acyclovir and valacyclovir have been used while breastfeeding. However, pregnant women and nursing mothers should contact their physician or pharmacist prior to using any medication. These medications are generally well tolerated with few side effects, though they may cause headache, nausea, or diarrhea. Doses may vary depending on the individual situation as determined by the prescriber.

Treatment for the first outbreak of oral herpes in an otherwise healthy person may include:

Acyclovir, 400 mg (milligrams) orally three times a day for 10 days or until the lesions have crusted
Valacyclovir, 2,000 mg orally every 12 hours for 1 day
Famciclovir, 250 mg orally three times a day for 7-10 days
Treatment doses for recurrent oral herpes are as follows:
Acyclovir, 400 mg orally three times a day for 5 days: It may also be given as 800 mg orally twice a day for 5 days or 800 mg three times a day for 2 days.
Valacyclovir, 2,000 mg orally every 12 hours for 1 day
Famciclovir, 1,500 mg orally once
Suppressive treatment for those with frequent outbreaks may be given for 12 months, but it may be extended if needed:
Acyclovir, 400 mg orally twice a day
Valacyclovir, 500 mg orally once a day
Famciclovir, 250 mg orally twice a day

What are the possible complications of oral
herpes (cold sores)?

"Autoinoculation" from touching a cold sore on the lip can cause herpes of the finger (herpetic whitlow). Autoinoculation occurs most commonly at the time of primary infection, when viral shedding is high and the immune system is still gearing up to contain it. The antibodies that are made after primary infection are usually — but not always — successful in preventing autoinoculation during recurrent attacks.

A more serious complication is infection of the eye, or ocular herpes (herpetic keratitis). It may be a mild surface ulceration with little discomfort, or it may cause deeper, painful ulcers that threaten vision. Ocular herpes is also caused by autoinoculation. If not treated, ocular herpes may lead to serious damage or even blindness.

Rarely, herpes simplex may infect the brain, causing encephalitis. This infection requires hospitalization and intravenous antiviral medications. HSV-1 is among the commonest causes of fatal viral encephalitis worldwide.

In immunocompromised people, such as those with HIV infection or those receiving chemotherapy, severe outbreaks of herpes may occur. Colds sores may spread to large parts of the lower face or invade organs. Antiviral drugs are used to prevent or lessen such attacks.

In a few people, outbreaks of herpes will be associated with erythema nodosum. Erythema nodosum is an inflammatory skin reaction characterized by red and painful skin lumps that usually appear on the front side of the legs. This condition can be caused by many inflammatory and infectious diseases, including herpes virus infections. Erythema nodosum can be self-limited and resolve on its own in 3 to 6 weeks. Treatment of the herpes episode usually hastens the resolution of erythema nodosum.

What is the prognosis for oral herpes (cold sores)? Can they be cured?

Currently, there is no cure or vaccine for herpes simplex virus. Avoiding risk factors, such as sunburn and stress, can help prevent additional outbreaks. Cold sores will usually heal within 2 weeks without treatment. However, there are established cold sore treatments available to help decrease healing time, reduce pain, and in specific cases, suppress the recurrence of the virus.

Cold sores, if they recur, are most likely to do so during the first year after infection. They usually resolve on their own within 1-2 weeks. After the initial outbreak, cold sores may never appear again, or appear only when something triggers them. Usually people with cold sores lead normal lives and are not terribly affected by them unless they happen to recur very often (several times a year or more).

Is it possible to prevent cold sores?

The best way to prevent a herpes simplex infection is to avoid physical contact with someone else's cold sores. Items that touch the lips but cannot be washed or sanitized, such as lipstick or lip balm, should not be shared. During an outbreak, frequent hand washing and sanitizing with 60% ethanol-based hand sanitizer will help reduce the spread of the virus to other parts of the body or to other people. Wash hands immediately after applying topical treatments to a cold sore. L-lysine and other supplements have not been shown to consistently reduce outbreaks.

To prevent future outbreaks,

avoid long periods of time in the sun and use sunblock on lips and face,
reduce stress by getting adequate rest and relaxation,
avoid trauma to the mouth or involved area, and
take any antiviral medication exactly as prescribed.