Oral herpes: everything you need to know about cold sores.

Cold sore: what is it exactly?

The cold sore, also called oral herpes, is a very common viral infection caused by the type 1 herpes simplex virus (HSV-1). It usually appears on the lips, at the junction between the skin and the mucous membrane, but it can also show up around the mouth or nose. The lesions often take the form of a small cluster of blisters filled with clear fluid, sitting on a red, slightly inflamed area. These blisters eventually break open, then a scab forms before the skin fully heals.

The appearance of a cold sore is often preceded by early warning signs, known as prodromes.

Several hours to two days before the outbreak, it is common to feel tingling, a burning sensation and/or itching on a small area of the lips. The blisters then appear quickly, and the episode typically lasts 7 to 10 days before resolving on its own. Although harmless in most cases, cold sores are contagious as long as the lesions are present, because the fluid inside the blisters is rich in viral particles. Saliva, via a shared kiss, a handshake, or sharing utensils or glasses, are all situations that promote the transmission of oral herpes.

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3.8 billion

of people under 50 years of age are carriers of HSV-1.

64%

of the global population carries HSV-1.

What is the origin of oral herpes (cold sores)?

The majority of the population carries the herpes simplex virus type 1, which is often contracted in childhood through direct contact with an infected person.

After this initial infection, the virus does not disappear: it remains in the body in a latent state, lodged in certain nerve ganglia located near the infected area. Most of the time, it stays silent, but it can occasionally reactivate, which leads to the appearance of a cold sore.

Several factors can promote this viral reactivation. A decrease in immune defenses, linked for example to fatigue, stress, a feverish infection, or certain immunosuppressive treatments, can trigger an episode of cold sores. Other factors are also known to promote recurrences, such as significant exposure to sunlight, hormonal fluctuations, local trauma (for example after dental work), or skin irritation. During the active phase of the outbreak, the cold sore is highly contagious and can easily spread to people nearby.

How can a cold sore be treated?

In most cases, a cold sore heals on its own within 7 to 10 days.

The main goal of treatment is therefore to relieve symptoms and shorten the duration of the herpes outbreak. At the first warning signs—tingling, burning sensations, or itching—topical antiviral treatments can be applied, usually in the form of a cream containing acyclovir or penciclovir. These medications work by slowing down viral replication and can slightly reduce the length of the episode if they are used early enough.

Cold sores: best practices.

Avoid touching the lesions, because the fluid contained in the vesicles is rich in virus and may promote the spread of the infection to other areas of the skin, including the eyes.
Wash your hands regularly, especially after applying a treatment to the cold sore.
Do not puncture the blisters or remove the scab, so as not to slow down the healing process.
Avoid close contact, such as kissing, especially with infants and immunocompromised individuals, who are more vulnerable to virus-related complications, and do not share objects that may come into contact with the mouth (glasses, eating utensils, towels, toothbrushes, etc.).
Protect your lips from the sun, because exposure to UV rays can promote recurrences.
Begin local treatments at the first signs to help limit the progression of the flare.

In certain cases, especially when flare-ups are frequent, extensive, or particularly painful, an oral antiviral treatment may be prescribed by a physician. Medications such as acyclovir, valacyclovir, or famciclovir can help reduce the intensity and duration of the outbreak. At the same time, a few simple measures can help limit discomfort: avoiding touching the lesions, keeping the area clean and dry, and protecting the lips from the sun with a lip balm with SPF. If symptoms are severe, last longer than about ten days, or occur in a person with a weakened immune system, it is important to consult a healthcare professional.

When should you see a doctor for a cold sore?

Contact your doctor in the following days if:

You have doubts about the nature of the lesions present on the lips or around the mouth.
The flare-up is more severe than usual.
The cold sore is spreading or has not healed after 10 days.
Recurrences are frequent (more than six episodes per year).

Contact your doctor during the day if:

The cold sore is accompanied by a high fever or significant pain.
You have eye symptoms in addition to the skin lesions (eye pain, redness, sensitivity to light), which may suggest a herpetic keratitis.
You are immunocompromised.