The Facts About Cold Sores

 Cold sores, or fever blisters, are common among Canadians.
Read the facts about cold sores and the virus that causes them
Fact: Cold sores are caused by a virus
  • Cold sores are caused by the herpes simplex virus. There are two types of this virus and cold sores are usually caused by type 1 (known as HSV-1). The other type of herpes simplex virus, HSV-2, usually causes genital herpes
  • In general, we are infected with HSV-1 when we are children; in the majority of these initial (“primary”) infections, there are no symptoms
  • Usually, the virus infects our mouths. Some children experience mouth and gum symptoms (“gingivostomatitis”) or a sore throat (“pharyngitis”).
Fact: Cold sores are the result of the virus reactivating in our bodies
  • Once HSV-1 has entered our bodies, it never leaves. The virus moves from the mouth to quietly reside (“remain latent”) in the central nervous system.
    About Cold Sores
  • In approximately one third of people, the virus can “wake up” or reactivate to cause disease
  • When reactivation occurs, the virus travels down the nerves to the skin where it may cause blisters (cold sores) around the lips, in the mouth or, in about 10% of cases, on the nose, chin, or cheeks
  • Many people who suffer from cold sores are aware in advance that a cold sore is about to break out — they have a tingling or burning feeling, redness, itching, or pain (“prodromal symptoms”) around their lips or mouth
  • Cold sore outbreaks may be influenced by stress, menstruation, sunlight, sunburn, fever, or local skin trauma.
Fact: The virus that causes cold sores is infectious
  • 30%-60% of children below 10 years of age are infected with HSV-1. They have acquired the virus from family and friends through sharing utensils or toothbrushes, and from kissing
  • The virus is transmitted from cold sores and also when there are no symptoms, as it can make copies of itself on the skin in the absence of a blister. This phenomenon is called “asymptomatic shedding”
  • By 50 years of age, 80%-90% of us harbour HSV-1 because we have caught it from someone close to us
  • HSV-1 can sometimes be transmitted to newborn babies by family members or hospital staff who have cold sores; this can cause a severe disease called neonatal herpes.
Fact: The virus from cold sores can infect other areas of the body
  • People can transfer the virus from their cold sores to other areas of the body, such as the eye, skin, or fingers; this is called “autoinoculation”
  • Eye infection, in the form of conjunctivitis or keratitis, can happen when you rub the cold sore, then rub your eyes before washing your hands
  • Finger infection (“herpetic whitlow”) can occur when a child with cold sores or primary HSV-1 infection sucks his/her fingers
  • HSV-1 can infect your genital area if you engage in oral sex with a partner with a cold sore
Fact: Early treatment can help eliminate the cold sore
  • Some products can accelerate healing if they are used at the prodromal stage of the cold sore
  • Prescription drugs include acyclovir cream or capsules (Zovirax®) and penciclovir cream (Denavir®); also, Health Canada recently approved a one day course of 2 grams valacyclovir caplets (Valtrex®) for prodromal use
  • Docosanol cream (Abreva®) can be bought without a prescription
  • Frequent hand washing minimizes the risk of transferring the virus to other areas of your body


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