Cold sores (fever blisters, herpes labialis)

Cold sores on the lips are caused by the herpes simplex virus (HSV).


Cold sores on the lips are caused by the herpes simplex virus (HSV). Almost all adults are infected with this virus and are what is known as “carriers”. When we are sick or stressed, the virus can multiply again. Painful blisters on the lips that itch or burn are typical. Ointments from the pharmacy can provide relief.


After the initial infection, the virus remains in the body for life and sporadically causes a relapse.

Symptoms for initial infection (aphthous stomatitis)

  • Blisters in the mouth, the lining of the mouth and the gums
  • Runny nose, inflammation of the tonsils and pharynx
  • Fever
  • The symptoms following initial infection can be so slight that they remain unnoticed

The symptoms disappear on their own after two to three weeks.

Symptoms for relapse (herpes labialis)

  • Fever blisters, mostly on the lips (rarely in the genital region, herpes genitalis)
  • Itching
  • Pain and a feeling of tightness
  • The blisters start crusting and heal without leaving a scar


Causes and treatment


  • Herpes simplex virus (HSV)
  • Initial infection through direct personal contact
    • The virus then stays dormant inside the nerve cells of the face, where it remains for life
  • It can be reactivated by illness, stress, sunlight, etc.

Further treatment by your doctor / in hospital

Possible tests
  • Blister swab (search for viruses)
Possible therapies
  • Anti-viral medication
    • Ointments
    • Tablets (rarely, only in severe cases)

What can I do myself?

  • Sore lips can be treated with chamomile tea, lemon balm oil or tea tree oil
  • Sucking on ice cubes helps to relieve the pain of blisters in the mouth (aphthae)
  • Sufficiently protect yourself against sunburn
  • Avoid stress as much as possible

When to see a doctor?

  • Serious relapse with many blisters
  • Very frequent relapses
  • Newborns and people with weakened immune systems

Exclusion of liability

CSS offers no guarantee for the accuracy and completeness of the information. The information published is no substitute for professional advice from a doctor or pharmacist.