Monitor the health of your community here

Prescription Medications for Cold Sores

Cold sores, also known as fever blisters, are lesions that occur as a result of an infection with the herpes simplex type 1 virus. Specific cold sore symptoms include small blisters around the mouth that can last for as long as 10 to 14 days. There are prescription medications for cold sores that can decrease burning and itching associated with these unsightly blisters.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Famciclovir ( Famvir) is a type of antiviral medication 2. It specifically stops the herpes virus from spreading throughout the body. says that famciclovir's minor side effects include:

  • dizziness
  • sleepiness
  • diarrhea
  • nausea
  • stomach pain
  • a skin rash 2

Famciclovir can also cause an allergic reaction, with signs such as

  • hives
  • difficulty breathing,
  • swelling of the throat
  • tongue or lips 2

Call 911 is you experience these side effects from famciclovir 2. Having a weak immune system, kidney disease and lactase deficiency may require a decrease in famciclovir's dose 2. Famciclovir is taken as a tablet daily or as a doctor prescribes 2.


Long-Term Side Effects of Valtrex

Learn More

Valacyclovir, typically sold as as Valtrex, is another antiviral medication that halts the progression of the herpes virus 3. Valacyclovir is used to treat cold sore in people who are at least 12 years old, and can also treat the chicken pox 3. Starting the drug as soon as you notice symptoms, in the prodromal period before the blisters appear, can significantly shorten healing time. Some of valacyclovir's minor effects include stomach pain, menstrual pain, a sore throat and a stuffy nose 3. Valacyclovir's serious side effects include confusion, lower back pain, vomiting, bloody diarrhea and yellowing of the skin 3. It is important to call a doctor when valacyclovir leads to these effects 3. Having HIV or AIDS or kidney disease may require a decrease in valacyclovir's dose 3. This medication is a tablet taken once a day or as prescribed.


Acyclovir, commonly sold as Zovirax, can stop the herpes virus that leads to shingles, the chicken pox and genital herpes. Some of acyclovir's serious effects include decreased urination, lower back pain, weakness, and easy bleeding or bruising. Acyclovir is given as a liquid or tablet taken once a day or as a doctor describes.