That’s because starting a medication when prodromal symptoms such as burning, tingling, or redness begin will give a person with a cold sore the best chance of either preventing an actual blister from forming or shortening a blister’s course once it does appear.

A Word on FDA Approval

A number of antiviral medications are used to treat herpes infections, which cause cold sores, also known as fever blisters.

While the FDA has approved the use of certain drugs for cold sores, some antiviral drugs aren’t specifically FDA-approved for cold sores but have been shown in clinical studies to be effective treatments. Given this, receiving a prescription for an off-label use of one of these drugs may help eliminate or prevent cold sores.

The decision to use a medication that is prescribed off-label should be made based on current scientific data and discussed thoroughly with your healthcare provider.

Treatment Benefits

Antiviral drugs can have several effects on oral herpes simplex viral infections, including cold sores. These medications can decrease the time that it takes for cold sores to heal and reduce symptoms, especially pain.

The First Outbreak

The first outbreak of any herpes simplex infection is usually worse than recurrent infections. An initial outbreak of oral herpes should be treated with oral medications, while recurrences can be treated with topical or oral medications.

The first episode (which generally occurs in childhood) is also treated longer, usually for seven to 10 days with an antiviral medication. Recurrent infections, on the other hand, are treated for a shorter period of time.

Topical Denavir for Cold Sores

Denavir (Penciclovir 1 percent cream) is FDA-approved for recurrent cold sores. Starting treatment within one hour of an outbreak can reduce healing time by two days, as well as reduce symptoms. Denavir can also decrease the duration of viral shedding.

Overall, the earlier Denavir is started, the better the benefits. That being said, improvement is often still possible when treatment is started after vesicles (the cold sores) develop.

Acyclovir

Zovirax (Acyclovir 5 percent cream) is also FDA-approved for the treatment of recurrent cold sores. In studies, frequent application of the cream reduced healing time by about 12 hours.

Oral acyclovir given five times a day for primary gingivostomatitis in children can substantially reduce the duration of fever, eating problems, and drinking difficulties, as well as viral shedding. Using low-dose oral acyclovir for cold sores can shorten the duration of symptoms, but higher doses may be needed to reduce pain.

Famciclovir

Famvir (Famciclovir) is approved by the FDA for the treatment of cold sores. If started at the first sign of symptoms, taking a single high dose of Famvir can shorten the herpes infection by two days.

Valtrex

Valtrex (Valacyclovir) is also approved by the FDA to treat cold sores and it’s a well-known, popular treatment. If started at the first sign of symptoms, taking Valtrex twice a day for one day can shorten the duration of a herpes infection.