Cold sores, also known as fever blisters, are small sores, or blister-like lesions on the face or inside the mouth. They usually cause pain, a burning sensation, or itching before they burst and crust over. Most commonly, cold sores appear on the lips, chin, cheeks, inside the nostrils, and less frequently on the gums or the palate (roof of the mouth).
Cold sores are caused by the herpes simplex viruses; the most common cause of sores around the mouth is herpes simplex type 1, or HSV-1. Much less commonly, cold sores may be caused by HSV-2 (herpes simplex type 2), which may result from having oral sex with a person who has genital herpes.
Cold sores are different from canker sores. However, people sometimes mistakenly associate one with the other. A canker sore is a small ulcer crater in the lining of the mouth - it is frequently painful. Canker sores are also known as aphthous ulcers. Canker sores occur in the soft tissue of the mouth, where cold sores do not appear.
Cold sores are quite common. There is no cure or prevention for infected people, but steps can be taken to reduce their frequency and duration.
The herpes simplex virus
The cold sore virus or herpes simplex virus is very contagious - it is easily transmissible from human-to-human as a result of close contact. When it enters a human, for most of the time it remains inactive (dormant). Occasionally, however, certain triggers activate the virus, resulting in a cold sore outbreak. Triggers vary, according to the individual. While one person may have just one outbreak and no recurrence, others may have two or three each year. Some people may carry the virus and never have an outbreak because it remains dormant all the time.
Contents of this article:
Fast facts on cold sores
Here are some key points about cold sores. More detail and supporting information is in the main article.
- Cold sores are tiny blisters that develop on the lips or around the mouth.
- Cold sores are caused by the herpes simplex virus strain HSV-1.
- On rare occasions cold sores may be caused by strain HSV-2 - a result of having oral sex with someone who has genital herpes.
- Cold sores usually clear within 7-10 days without treatment.
- The herpes simplex virus is highly contagious and can be easily passed from person to person by close direct contact.
- After someone has contracted the "cold sore virus", it remains inactive for most of the time.
- The virus can be activated by triggers such as fatigue, injury to the affected area, and in women - their period.
- Some people have cold sores recur around 2-3 times per year.
- Statistical studies suggest that about 80-90% of people in the US have been exposed to HSV-1 and about 30% have been exposed to HSV-2.
- It is not possible to completely prevent becoming infected with the herpes simplex virus or to prevent outbreaks of cold sores.
- If you have unhealed cold sores, it is particularly important to avoid close contact with people with weakened immune systems.
Signs and symptoms of cold sores
A symptom is something the patient feels and reports, while a sign is something other people, including a doctor or a nurse may detect. For example, pain may be a symptom while a rash may be a sign.
Many people infected with the herpes simplex virus have no symptoms and will never know they are infected, until an outbreak of cold sores occurs (if ever one does). If there are symptoms with a primary infection, they may be severe.
Signs and symptoms of the primary infection
(Primary infection - the original outbreak of an illness against which the body has had no opportunity to build antibodies.)
In the majority of cases there are no detectable signs or symptoms. When they do occur, usually in very young children, they may be severe, and can include:
- Mouth or tongue lesions
- Blisters in the mouth
- Mouth ulcers
- Mouth or tongue pain
- Lip swelling
- Possible swallowing difficulties
- Sore throat
- Swollen glands
- Elevated body temperature
- Dehydration (body does not have enough water)
Cold sores commonly develop on the lips or around the mouth
Herpes simplex gingivostomatitis may last from one to two weeks. The sores may take as long as three weeks to heal up. After the primary infection, gingivostomatitis does not recur; just normal cold sore outbreaks may recur. Although adults can get gingivostomatitis, most patients are young children.
Adults with primary infection usually have pharyngotonsillitis - the tonsils will swell, the individual will have a sore throat and glandular fever-like symptoms. The glands may or may not swell. A significant number of patients will have foul-smelling breath (halitosis) and painful sores around the mouth. These sores sometimes develop into ulcers with grayish-yellowish centers.
Individuals who were infected when they were children may have occasional bouts of cold sores later in life. However, after the primary infection, signs and symptoms are generally limited to just those of cold sores.
Cold sore signs and symptoms (symptoms of recurrent infection)
A recurrent infection is nearly always less severe and shorter-lasting than the primary infection. There will be an outbreak of cold sores, with the possibility swollen glands (less common).
Patients say a tingling, itching or burning sensation around the mouth often indicates the onset of a cold sore outbreak. This is followed by fluid-filled sores, typically located on the edges of the lower lip.
People with regular recurrences say the cold sores often appear in the same place. As the cold sore grows in size, so does the pain and irritation. They will form, break and ooze (weep). A yellow crust forms and sloughs off to uncover pink skin that heals without scarring.
In the majority of cases the cold sore is gone within a week or two.
What causes cold sores?
Most cases of cold sores are a consequence of infection with HSV-1 (herpes simplex virus type 1). Infection with HSV-2, usually resulting from oral sex with a person who has genital herpes, is a much less common cause of cold sore outbreaks.
HSV-1 is typically passed on in early childhood when a child is kissed by a person with a cold sore. Shared eating utensils, bathroom items, such as towels or razors, may spread the infection. The virus makes its way to the nerves and lies there dormant until some trigger activates it later on.
The following triggers are known to potentially activate the virus:
- Mental stress
- Deep sadness or upset
- An injury to the affected area
- Intense sunlight.
On the next page we look at how to diagnose a cold sore and the possible treatment options for cold sores.