Valacyclovir vs Famciclovir
Valacyclovir (Valtrex) and famciclovir (Famvir) are both well-absorbed antiviral prodrugs with convenient dosing for herpes, cold sores, and shingles. They are clinically similar for most uses.
Antiviral (nucleoside analogue prodrug)
Antiviral (nucleoside analogue prodrug)
A prodrug of acyclovir with better absorption, so it can be dosed just once or twice a day for herpes, cold sores, and shingles.
A prodrug of penciclovir with convenient short-course dosing, often used for recurrent herpes, cold sores, and shingles.
Herpes / cold sores / shingles
Herpes / cold sores / shingles
- Genital herpes (treatment and suppression)
- Cold sores (herpes labialis)
- Shingles (herpes zoster)
- Chickenpox in children
- Genital herpes (recurrent treatment and suppression)
- Cold sores (herpes labialis)
- Shingles (herpes zoster)
- Genital herpes, initial episode: 1 g twice daily for 7–10 days
- Genital herpes, recurrent: 500 mg twice daily for 3 days
- Genital herpes, suppression: 500 mg–1 g once daily
- Cold sores: 2 g twice daily for one day
- Shingles: 1 g three times daily for 7 days
- Genital herpes, recurrent: 1 g twice daily for one day
- Genital herpes, suppression: 250 mg twice daily
- Cold sores: 1.5 g as a single dose
- Shingles: 500 mg three times daily for 7 days
- Headache
- Nausea
- Abdominal pain
- Dizziness
- Acute kidney injury (especially with dehydration or high doses)
- Central nervous system effects such as confusion or hallucinations, mainly in older or renally impaired patients
- Thrombotic thrombocytopenic purpura / hemolytic uremic syndrome in advanced HIV or transplant patients at high doses
- Headache
- Nausea
- Diarrhea
- Fatigue
- Acute kidney injury (rare, mainly with dehydration or renal impairment)
- Confusion, mainly in older or renally impaired patients
- Urticaria and other hypersensitivity reactions
- Adults with genital herpes, cold sores, or shingles
- People who prefer fewer daily doses than acyclovir
- Adults with recurrent genital herpes, cold sores, or shingles
- People who prefer very short treatment courses
- Known hypersensitivity to valacyclovir or acyclovir
- Known hypersensitivity to famciclovir, penciclovir, or the topical product Denavir
- Reduce the dose in kidney impairment
- Maintain adequate hydration
- TTP/HUS has occurred at high doses in severely immunocompromised patients
- Use caution in older adults, who are more prone to CNS side effects
- Reduce the dose in kidney impairment
- Efficacy for a first (initial) genital herpes episode has not been established
- Maintain adequate hydration
- Use caution in older adults, who are more prone to CNS side effects
Bottom line: which should I choose?
Choose valacyclovir for the broadest evidence base and lower typical cost, including approved use for a first genital-herpes episode. Choose famciclovir if you prefer its specific short-course regimens or have tolerated it better before, keeping in mind it is not established for an initial herpes episode. Both are dose-adjusted for kidney function and both work best when started early.
Common questions
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