Herpes labialis also known by the popular names “cold sores”, “oral herpes” or “fever blisters,” appears as a cluster of painful blisters, usually on and around the lips. Exceptionally, these small pimples may appear on the nose, the edge of the ear, the chin, or on the cheeks.
Cold sores are an infection caused by a virus called herpes simplex virus type 1 (HSV-1). In some cases, herpes simplex virus type 2 (HSV-2) may also be involved. However, HSV-2 is usually associated with genital herpes.
It is a mild but uncomfortable and often recurrent condition. On average, symptoms resolve on their own within 7 to 10 days.
HSV-1 infection is widespread. Depending on the region of the world, between 50% and 90% of the population is infected with HSV-1. The initial infection usually occurs before the age of 20, especially in early childhood, and usually causes no symptoms. In fact, most infected people will never have symptoms, so there are no obvious blisters. The virus is in the body but remains inactive.
Mode of transmission
Once infected with HSV-1, the virus remains in the body for life without causing permanent symptoms. People infected with this virus are called carriers. The virus lurks in the nerve ganglia at the base of the skull (e.g., trigeminal ganglion).
From time to time, for various reasons (fatigue, fever, sun exposure, etc.), the virus “wakes up” and triggers a herpes outbreak, always at the same site. The frequency of these outbreaks varies greatly from person to person. For reasons that are not yet known, some people do not have a recurrence. Others have a few or more outbreaks per year.
Cold sores are contagious to people who have never been infected with the virus, especially those with weakened immune systems. If the lesions reappear, it does not mean that it is a new infection. Therefore, reactivations of the virus are not related to recent contact with an infected person.
Human from person to person
This virus is highly contagious. The incubation period is 1 to 6 days.
The period of greatest risk occurs when the vesicles rupture. The transmission then occurs through direct contact with the blisters or contaminated objects (utensils, towels, etc.) or saliva. The fluid in the blisters contains viruses that can penetrate the oral mucosa and infect a new person. The lesions are contagious until they are completely dry.
The virus can also spread through saliva when symptoms are not present, but this is less common. Some reactivation phases of the virus occur without causing lesions on the lips. A person may even get cold sores from someone who is unaware that they are carrying the virus.
In adults, kissing and oral/genital sexual contact are the main routes of transmission. Thus, cold sores can lead to genital herpes and vice versa.
Transmission in the same person
In rare cases, the virus can spread from the lips to other parts of the body if fingers touch the lesions, and then to the mucous membranes of the eyes (conjunctivitis or corneal ulcer), the inside of the mouth (gingival herpes stomatitis), the nose, and the genitals (genital herpes). Lesions may also occur on the fingers.
Herpetic lesions, which are embarrassing, can occur at the wrong time. They have no significant health consequences, except for people with weakened immune systems (for example, because of medications, AIDS, or other diseases that weaken the immune system). In these people and in young children, HSV-1 infection can lead to serious complications.
When to go see a doctor?
- For lesions that do not heal within 1 to 2 weeks.
- When there is a fever or very severe symptoms during a herpes outbreak.
- When flare-ups are frequent.
- In the case of a disease that affects the immune system.
- If the eyes become sensitive to light during or after an outbreak, which may be a sign that the infection has spread to the eyes.
Symptoms of Oral Herpes
First cold sore breakout
- In most cases (90% of cases) there are no symptoms.
- When symptoms are present, they are often severe, especially in young children. The lips and the entire mouth may be affected so severely that the child has difficulty swallowing. This is called acute gingivostomatitis. A high fever is often present. Spontaneous healing of the lesions may take up to 14 days.
Relapses correspond to the reactivation of the virus, which then causes an outbreak of cold sores.
- Recurrence is often preceded by the following symptoms: tingling, itching, burning, swelling, and numbness at the edge of the lips. General malaise (fatigue, fever) may occur.
- A few hours to 1 day later, a series of small, painful red blisters appear. Filled with fluid, they eventually burst and form a crust.
People at risk and risk factors for cold sores
People at risk
- People who are carriers of herpes simplex virus type 1 (most adults).
- People with weakened immune systems are more prone to frequent recurrences and prolonged outbreaks of herpes. These include people infected with HIV/AIDS or those undergoing treatment for cancer or autoimmune disease (immunosuppressive therapy).
Once the virus has broken out, several factors contribute to the recurrence of symptoms:
- Anxiety, stress, and fatigue.
- A rise in temperature, either from fever or sun exposure.
- Dry lips.
- Flu, a cold, or other infectious diseases.
- Local trauma (dental work, facial cosmetic work, cuts, cracked skin).
- Poor diet.
- Taking immunosuppressants.
Prevention of cold sores
Since HSV-1 infection is very common and mainly transmitted in childhood, it is very difficult to prevent it. However, the following precautions can be taken.
Precautionary measures to avoid catching oral herpes
- Avoid kissing someone who has a cold outbreak until the blisters are completely dry. The fluid inside the blisters contains the virus.
- Avoid using utensils or objects that may have been in direct contact with an infected person’s saliva or mouth, especially during an outbreak.
- Avoid oral/genital contact during an outbreak of cold sore or genital herpes in a partner. Herpes simplex type 2 virus (the virus that causes genital herpes) can also cause cold sores.
Measures to prevent a relapse
Determine the triggers: First, try to identify the circumstances that contribute to the relapse. Try to avoid them as much as possible (stress, certain medications, etc.). Sun exposure is a common relapse factor for many people. In these cases, apply sunscreen to your lips (SPF 15 or higher) in both winter and summer. This is even more important at high altitudes and in tropical regions. You should also moisturize your lips with a hydrating balm. Dry, chapped lips are fertile ground for lesions.
Boost your immune system: Experts believe that controlling a herpes virus infection depends largely on a strong immune system. A weak or deficient immune system contributes to recurrences. Some key factors:
- A healthy diet
- Getting a good night’s sleep
- Physical activity
Taking antiviral medications: As a preventive measure, your doctor may prescribe antiviral tablets for more severe cases: frequent, large rashes, people with immune deficiency, or AIDS. This may help reduce the frequency of recurrences.
Medical treatments for cold sores
There is no medical treatment that permanently eliminates this virus from the body. There is however promising research that may one day lead to a cure.
Because symptoms disappear on their own within 7 to 10 days, most people choose not to seek medical treatment.
However, there are treatments that can relieve the symptoms and shorten their duration somewhat:
- Tylenol helps relieve the pain
- Penciclovir cream (Denavir®). Applied every 2 hours (except during sleep), 1% concentrated penciclovir cream slightly speeds healing. It is available by prescription. According to one study, healing occurs in 4.8 days with penciclovir compared with 5.5 days with placebo. It is always best to apply immediately after symptoms appear. This cream retains some efficacy even after the lesions have been present for a few days.
- Acyclovir cream (Zovirax®). It is applied to the cold sore 4 to 5 times daily for 5 days to reduce the duration of the outbreak. The cream is most effective if applied as early as possible.
- Docosanol Cream. When symptoms first appear, applying 10% docosanol cream to the lesion prevents the virus from multiplying. It is applied 5 times daily until the lesion heals, for up to 10 days. In a clinical trial, docosanol cream accelerated healing by an average of 18 hours (healing in 4 days vs. 4.8 days with placebo).
- Oral treatments. These medications are most effective when taken at the onset of the first symptoms:
Famciclovir. This is a 1-day treatment taken in 2 doses. According to one study, the average duration of lesions was 4 days instead of 6.2 days in the placebo group.
- Acyclovir (200 mg three to five times daily): accelerates healing if taken early at the first signs.
- Valacyclovir: 2 recent clinical trials showed that oral administration of 2 g of valacyclovir for 24 hours reduced the duration of attack and pain by about 1 day.
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What to do if an outbreak occurs
Do not touch the lesions or the virus will spread to other parts of the body and delay healing. If it is touched, wash your hands immediately afterward.
Do not share glasses, toothbrushes, razors, or towels to prevent the spread of the virus.
Avoid intimate contact, kissing, and oral/sexual intercourse during the outbreak.
Avoid contact with children, persons with eczema, and persons with weakened immune systems (e.g., organ transplant recipients).
Measures in case of pain
Place ice (ice cubes on a damp towel) on lesions for a few minutes several times a day.
Keep lips well moisturized.
Most sufferers do not seek medical attention. Those who do see a doctor, for this reason, are often people who have frequent relapses. In these cases, it is a good idea to follow the advice described on this sheet: Discover the triggers, limit stress, strengthen your immune system. Doctors usually prescribe a 24-hour antiviral treatment that the person receives in advance. This is the only way to ensure that the person can act in time before the next cold sore outbreak.