UT University Health Services

Cold Sores / Fever Blisters

Cold sores, also known as fever blisters or oral herpes, appear on the lips, on the gums, or in the mouth. Cold sores are highly contagious and very common.

Oral herpes (cold sores, fever blisters) and genital herpes are both caused by viruses in the herpes family. Cold sores can be triggered by stress, illness, exposure to the sun or wind, menstrual periods, dental treatment, or other events, but not every outbreak can be associated with a specific trigger. There is no cure for the virus that causes cold sores. Some people can reduce the number and severity of cold sores by figuring out what triggers them and avoiding those things.

Like genital herpes, oral herpes can be spread to other people or to other parts of your body even when sores are not present. Even though there is no cure, you can minimize discomfort and transmission. The following information pertains to cold sores in or around the mouth. To find out more about genital herpes, click the link below.

Genital Herpes

Signs and Symptoms

  • About 6 to 48 hours before a cold sore appears, you may feel itching, tingling, burning and/or pain at the outbreak site. You may run a low fever (less than 100.5 degrees F or 38 degrees C). This is called the prodromal period. You can transmit the viruses at this time even though sores aren't yet visible. Not everyone who gets cold sores will notice symptoms during the prodromal period.
  • Small, painful blisters appear. They break and ooze a clear fluid, form a painful sore, and then form a crust or a scab. Cold sores usually heal on their own.


Herpes viruses are spread by touch. If you get cold sores, it is very important to wash your hands often and keep your hands away from your face. A cold sore is contagious during the prodromal period and when a sore is visible, but herpes viruses can be spread even when there are no symptoms or sores. The viruses can spread to other areas of the body and can be transmitted to the genital area during oral sex. If you touch a cold sore and then touch your eyes, your eyes could become infected, which can lead to major vision problems.

Since cold sores are so contagious, avoid kissing and oral sex from the prodromal period until the sores are healed.


  • Don't rub or scratch a cold sore. If you apply medication, use a cotton swab.
  • Wash your hands frequently. Keep hands away from the eyes, mouth, and genitals.
  • Avoid spicy, salty, or acidic foods.
  • Take a non-prescription pain medication or hold a piece of ice on a sore.
  • Use an over-the-counter drying or soothing agent such as Anbesol, Orabase, or Blistex. Be sure to follow the package instructions and don't apply these products on your genitals or inside your mouth.
  • Apply an over-the-counter antiviral cream or gel such as Abreva. For best results, start using it as soon as prodromal sensations first occur, but definitely within 24 hours of the onset of symptoms.
  • Remember, avoid kissing and oral sex from the prodromal period until the sores are completely healed.
  • Be advised: herpes viruses can be transmitted even when there are no prodromal sensations or visible sores.

Over the Counter Medications for Cold Sores and Fever Blisters

  • Brand names listed as examples do not imply better quality over other brands. Generic equivalents may also exist.
  • Use only as directed on the package, unless your healthcare provider instructs you to do otherwise.
  • OTCs may interact with other medications or be potentially harmful if you have certain medical conditions. Talk to your pharmacist about options that are right for you.

Cold Sores / Fever Blisters:
Docosanol (example: Abreva®)
example: L-Lysine®


  • Pain that makes you unable to eat or drink
  • Sores on your genitals, near your eyes, or in or near your nose
  • Any indication that your eyes are infected such as redness, pain, or swelling
  • Signs of a secondary infection such as increased tenderness, swelling, greenish-yellow oozing (pus), or a fever of 100.5 F (38 degrees C) or higher
  • Sores that don't heal within two weeks or new sores continue to appear

Additional Resources

Genital Herpes

Forty Acres Pharmacy

UT University Health Services UT University Health Services

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