Fever blisters are another name for cold sores, which are caused by the herpes simplex virus type I; type II is associated with genital herpes but can also cause lesions on or around the mouth. Most adults carry latent HSV-I and are asymptomatic. In some individuals, the virus reactivates and causes fever blisters, which can be treated with antiviral medications. These medications can be prescribed for a limited time to treat a single breakout, or as a long-term therapy to reduce the occurrence of outbreaks and the spread of the virus by shedding, says the American Academy of Dermatology.
Acyclovir
Acyclovir medication is available in capsule from, as an intravenous treatment and as an ointment. It has inhibitory activity against herpes simplex viruses type I and II, as well as the varicella-zoster virus. It inhibits viral reproduction by interfering with certain steps of viral replication. Side effects included nausea in about 5 percent of long-term users and diarrhea in about 3 percent of users who took the drug for periodic outbreaks.
Valacyclovir
Valacyclovir, also known by the brand name Valtrex, is used to treat both oral and genital herpes, as well as herpes zoster, which is responsible for shingles. Valacyclovir had a greater number of reported side effects, including headache and dizziness. Gastrointestinal upset such as constipation, diarrhea, vomiting or upset stomach may also occur. Serious side effects including kidney failure have been rarely reported. Treatment for cold sores consists of no more than two doses of the medication, spaced 12 hours apart.
Famciclovir
Famciclovir is used for the treatment of oral herpes and herpes zoster, but generally only in people with normally functioning immune systems, notes PubMed Health from the National Institutes of Health. Famciclovir may aid in sore healing and prevent new sores, as well as decreasing the symptoms of itchiness, pain, burning and tenderness in fever blisters. Famciclovir is generally taken as only one dose when treating fever blisters.
References
- DailyMed: Acyclovir
- "Current Medical Diagnosis & Treatment"; Timothy G. Berger, MD; 2010
- PubMed Health: Famciclovir
- RxList: Valtrex
- American Academy of Dermatology: Herpes Simplex
