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Cold sores - symptoms, diagnosis, treatment and prevention

What are cold sores?

Cold sores are a painful infection caused by the herpes simplex virus (HSV). These sores are usually caused by HSV Type 1 but can less commonly be due to HSV Type 2.They are most likely to appear on the gums, the outside of the mouth and lips, and the nose. Blisters form, then break and ooze; a yellow crust develops and eventually comes off, revealing new skin underneath. The sores usually last seven to 10 days and are contagious until they crust over completely.

90% of all people get at least one cold sore in their lives. This first occurrence is often the worst. Some children who are affected may become seriously ill. After the first infection, many people develop antibodies and never have another cold sore.
Although cold sores are generally not serious, the infection may be life-threatening for anyone who has HIV infection or has AIDS or whose immune system is suppressed by other disorders or medications.

The infection from a cold sore may cause blindness if it spreads to the eye and meningitis or encephalitis if it spreads to the brain.

What causes cold sores?

Cold sores are usually caused by the herpes simplex virus (HSV) type 1, which is transmitted by such forms of contact as kissing an infected person or sharing eating utensils, towels or razors. Genital herpes is usually caused by herpes simplex virus Type 2 but can also be caused by HSV type 1. A person with a cold sore who performs oral sex on another person can give that person genital lesions with HSV type 1 and similarly, genital HSV type 2 lesions can be spread to the lips.

Sores may develop as late as 20 days after exposure to the virus. Once the virus enters your body, it may emerge years later at or near the original site of entry. About two days before an attack you may experience itching or sensitivity at the site. The virus may be triggered by certain foods, stress, fever, colds, allergies, sunburn and menstruation.

What are the symptoms of cold sores?

  • Fluid-filled blisters or red, painful sores on or near the mouth.
  • Swollen, sensitive gums of a deep red colour.
  • A fever, flu-like symptoms and swollen lymph nodes in the neck often accompanying the first attack. 

Recurrent sores usually don't produce these symptoms.

Tingling and itching in the area of a previous outbreak may be symptoms of a recurrence.

Seek medical advice about cold sores if:

  • You develop a high fever and/or chills; high fevers can be dangerous.
  • Your sores are very painful; you may be able to get prescription relief.
  • You have early signs of infection. Antiviral agents may shorten the course of illness only if started early. You can buy anti-viral cream such as aciclovir from the pharmacy or your doctor may give you a prescription for cream or tablets.
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