What is a cold sore

What is a cold sore?

Cold sores are also known as a fever blister that usually forms on the lips or around your mouth. A cold sore is one of the most common viral infections. It’s an infection caused by a virus called the Herpes Simplex Virus, usually “type-1” (HSV-1).

The Herpes Simplex Virus is also called the cold sore virus. The herpes simplex virus is most often acquired through kissing, close personal contact, or sharing food and utensils with an infected person. It may also be spread by hand or glasses, after contact with cold sores, so it is important to wash your hands frequently and glasses thoroughly. The herpes simplex virus is contagious from the first sign of an outbreak until it is completely healed.

The cold sore is marked by a fluid filled blister that makes the skin red and swollen. The blisters of the cold sore are often very painful. As these blisters are filled with fluid, the upper layer is very tender and rubbing them can lead to severe infection. If medication is taken on time, the blisters can be healed without any scar formation.

Yet, in most cases, the blisters have tendency to reappear. Unlike most other viruses, when the herpes simplex virus enters your body it never leaves. After the first infection, the virus travels to an area of your face called the trigeminal nerve ganglion. There is a trigeminal nerve ganglion on each side of your face and it is located slightly in-front of your ear. Here the virus hides from the body’s immune system by becoming dormant or “sleeping”. Some triggers (like stress, fatigue, exposure to intense sunlight) “wake up” the virus which then becomes active in people who get cold sores. The nerves that provide sensation to your face (trigeminal nerves) branch out from where the herpes simplex virus is hiding. When the virus “wakes up” it travels down these nerves to your lips and mouth area, eventually infecting lip cells. Cold sores usually take place close to the original infection site. Infected lip cells become the visible sores we call cold sores.

Who gets a cold sore?

Anyone can get the cold sore virus (herpes simplex). It is estimated that by the age of 15 more than 40% of people have been exposed to the herpes simplex virus. And that number increases to 80-90% for older adults. Just because someone gets the herpes simplex virus doesn’t mean they’ll develop cold sores. For many, about 20-40%, repeated outbreaks are common. Men and women are equally likely to suffer from cold sores, at any age.

If you get cold sores you may experience typical cold sore symptoms such as unusual sensations around your lips and mouth, signalling that a cold sore is about to develop. Not everyone experiences the same degree of discomfort during a cold sore outbreak. The size of the cold sore and the length of time it takes to heal may be different as well. Depending on the stage of their outbreak many people report different symptoms while it takes place.

What causes cold sores?

There are many triggers for a cold sore to appear or to activate the cold sore virus (herpes simplex). Cold sore outbreaks are generally a result of psychological or physical stress.

Common triggers include:

• Fatigue
• Low immune system
• Illness such as fever and cold
• Cold weather
• Exposure to intense sunlight (UV)
• Monthly period
• Dry or chapped lips
• Injury to the lips (e.g. after dentist treatment, hot tea, etc)

Not everyone’s cold sore outbreak is trigged by the same trigger. Cold sore causes vary from person to person. Try to identify what may cause your cold sore outbreaks, and help avoid the cold sore developing.

Cold sore symptoms

The primary infection of the cold sore virus (herpes simplex) can develop in different ways. It may cause mild symptoms or no symptoms at all. After the primary infection, with or without symptoms, the virus lies dormant in your body but can reactivate and cause lip blisters (cold sores). If you get cold sores you may experience some unusual sensations around your lips and mouth signalling that a cold sore is about to develop. Many people report the following cold sore symptoms during an outbreak:

• Tingling
• Itching
• Burning
• Numbness
• Swelling
• Redness
• Throbbing
• Pain
• Scabbing
• Bleeding
• Flaking

Symptoms may not start for up to 20 days after exposure to the herpes simplex virus, although it’s more typical for cold sores to appear within about one week of exposure. Cold sores usually clear up within about two weeks. Recurrent outbreaks usually occur in or around the same place each time, and it’s possible to have three or more cold sore outbreaks a year.

Cold sore stages

There are 4 main stages to the life cycle of a cold sore. The herpes simplex virus is contagious during every one of these stages. Together, the 4 stages typically run 7 to 10 days, but can sometimes last up to 2 weeks or longer. It’s important to contact your doctor once a cold sore lasts for more than 14 days.

Stage 1: The Tingle Stage (days 1-2)
Before any visible cold sore appears you may experience some unusual sensations around your lips and mouth that indicate a cold sore is about to develop. This stage is commonly called the “Tingle Stage” and about 70% to 75% of people may experience these initial cold sore symptoms. Usually, you can feel the skin tightening in the area where the cold sore is about to develop. As a reaction to the infection, the area becomes red and swollen. Even at this early stage, the infection is contagious. So avoid close, physical contact if you feel a cold sore coming on.

Stage 2: The Blister Stage (days 2-4)
This is the stage where the cold sore blisters appear. The area turns red and painful. Clusters of small blisters are formed, which can grow into one large blister. The blister is fluid and contains millions of virus particles.

Stage 3: The Ulcer Stage (days 4-5)
Typically the most painful, the ulcer stage happens once the blisters burst. This stage is when you develop an open sore and it is the most infectious stage.

Stage 4: The Healing Stage (days 5-10)
The blisters dry up and a crust forms that is yellow or brown in colour; it forms a scab. As the scab shrinks, you may experience painful cracks that can bleed. A series of scabs will form over the sore, each smaller than the previous one, until the cold sore is completely healed.

Herpes simplex labialis

Cold sores are caused by the herpes simplex virus (HSV). There are two types of herpes simplex virus: HSV-1 and HSV-2. Both virus types can cause sores around the mouth (herpes labialis) and on the genitals (genital herpes). A cold sore is usually caused by HSV-1 and HSV-2 is the main cause of genital herpes. The herpes simplex virus usually enters the body through a break in the skin around or inside the mouth.

It is usually spread when a person touches a cold sore or touches infected fluid. Such as from sharing food and utensils with an infected person, through kissing, close personal contact. A parent who has a cold sore often spreads the infection to their child in this way. Cold sores can also be spread to other areas of the body/face.

Impetigo and a cold sore are often confused. A cold sore is caused by the herpes simplex virus. Impetigo is a highly contagious skin infection and it is caused by bacteria.

Impetigo, which is one of the most common skin infections among kids, usually produces blisters or sores on the face, neck, hands, and nappy area. This contagious superficial skin infection is generally caused by one of two bacteria: Staphylococcus aureus or Streptococcus pyogenes (also called group A streptococcus, which also causes strep throat). Methicillin-resistant Staphylococcus aureus (MRSA) is also becoming an important cause of impetigo.