Cold Sores Causes, Symptoms & Full Risks Explained

Cold Sores Pictures

Despite the name, cold sores are not caused by cold. Cold sores, also known as herpes labialis are small, painful blisters that usually form on the lips or skin around the mouth, nose and on the chin. These sores appear like tiny, fluid-filled blisters on and around your lips. In most cases, the sores usually appear as clusters of tiny blisters on the lip or on the skin around the face.

Causes of cold sores

Generally, cold sores are caused by infection with the herpes simplex virus (HSV). Most people out there are usually infected in their childhood before they are 10 years old. Herpes simplex virus (HSV-1) is commonly picked it up when you were a kid, most likely from direct contact with someone who has it or getting kissed by an adult with the virus. You can catch HSV when you come into contact with people or things that carry the virus. For example, you can get the virus from kissing someone who is infected or when you share drinking glasses, eating utensils, towels or toothbrushes. (1)

The bad thing here is that the virus stays in the body throughout lifetime and there’s no permanent cure to get rid of them. However, the first infection does not usually cause any symptoms, the virus tends to remain inactive inside the body. Once an individual gets infected with HSV-1, the virus makes its way through the skin and into a group of nerve cells called a ganglion and remains inactive for some time. (2)

In rare cases, the herpes simplex virus (HSV-1) stays dormant (asleep) permanently without causing any problem. Well, in most cases, the virus tend to “wake up” or become active after a long period of time. No one knows for sure what causes this virus to wake up, but once they do they lead to cold sores outbreak.

Well, certain factors such as emotional or physical stress, as well as other infections, fever, excessive exposure to sunlight, exposure to windy conditions, hormonal changes during menstruation or pregnancy, tooth extractions, and certain foods and medications can possibly awake the virus.

The formation of cold sore

  • At first the herpes simplex virus-1(HSV-1) which has been lying dormant in the body, becomes active.
  • The virus spreads out through the nerve endings towards the soft tissues below the lips, genitals, nose, cheeks, or fingers.
  • You will start to experience tingling itchy, or burning sensation at the area where the sores wants to develop. That particular area is where the cold sore is going to appear.
  • After a day or two, a red bump appears in that area after the tingling, itching or burning sensation.
  • Small fluid-filled blisters forms and break out along the border where the outside edge of the lips meets the skin of the face.
  • After the blisters have formed, you may notice that they break and ooze. A yellow crust or a scab builds up and eventually falls off, revealing new skin underneath.

Normally, the sores last for about 7 to 10 days. At this point, they are very contagious and can spread to other people until they crust over completely. HSV-1 can also infect the eyes, the skin of the fingers and the genitals. Although, most genital herpes infections are caused by herpes simplex type 2 (HSV-2). This type of infection is often referred to as herpes whitlow. Children who suck their thumbs may transfer the infection from their mouths to their thumbs.

Symptoms of cold sores

Cold sores, also known as fever blisters, can show up anywhere, they most appear on the outside of the mouth, lips, on the nose, cheeks, or fingers. The signs and symptoms vary depending on certain factors. People usually experience more severe symptoms during their first outbreak. Recurrences typically appear at the same spot each time and tend to be less severe than the first outbreak.

People who are infected with HSV-1 for the first time may have severe fever, headache, nausea and vomiting. In some rare cases, cold sores may also develop inside the mouths and the lesions are commonly mistaken for canker sores. Well, when you become infected with HSV-1 for the first time, you may experience:

  • fever
  • tiredness
  • blisters (lesions) and ulcers in and around the mouth
  • a sore throat
  • pain inside the mouth and on the gums
  • swollen neck glands (lymph glands)
  • Painful eroded gums
  • Headache
  • Muscle aches

The symptoms can last up to a week or more and may cause lots of pain and discomforts. In severe cases, the infection can actually progress to the eye and affect your vision. Eventually, it may also spread to the brain and could lead to meningitis or encephalitis.

Risk factors

According to studies, about 90 per cent of adults have herpes simplex antibodies in their bloodstream, which means that they have been infected with the virus at some time. Generally, cold sores are not serious, but the infection can progress over time and may be life-threatening for anyone who has a weakened immune system. People whose body defense against germs has been curbed by immune system disorders or medications are at higher risk of complications from the virus.

Some medical conditions and diseases such as – HIV/AIDS, eczema, cancer chemotherapy and anti-rejection drugs for organ transplants can increase your risk of complications.


  • Avoid skin-to-skin contact with infected people. To help to prevent a first herpes infection in children do not let them be kissed by anyone who has cold sores, fever blisters or signs of a first herpes infection.
  • Medications. Since most people are usually infected during their childhood, there are medications to protect your children from being infected. There are special vaccines that are being developed against HSV (types 1 and 2), but these medications are mostly to protect only people who have never been infected.
  • Always wash your hands. If you do touch an active cold sore, don’t touch other parts of your body, wash your hands as soon as possible. To help avoid spreading cold sores to other people or to other parts of your body especially your eyes, always wash your hands.
  • Avoid sharing items. Avoid sharing toothbrushes, drinking glasses or bottles, cutlery, towels or other personal items. Ensure to avoid close contact such as kissing and hugging with adults or children that have burns, eczema or other symptoms of cold sores.

Learn more about cold sores here – all about cold sores. 

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