Valacyclovir vs acyclovir: herpes and shingles medicines compared
Valacyclovir (Valtrex) turns into acyclovir in the body but is absorbed far better, so it is taken fewer times a day for the same infections: cold sores, genital herpes and shingles. Acyclovir comes as a liquid and costs less per tablet; valacyclovir is simpler to take.
Updated October 4, 2026
At a glance
- How it works
- Valacyclovir
- Converted to acyclovir after absorption
- Acyclovir
- Acts directly
- Doses a day
- Valacyclovir
- Usually two or three
- Acyclovir
- Usually two to five
- Approved for
- Valacyclovir
- Cold sores, genital herpes, shingles, chickenpox in children
- Acyclovir
- Genital herpes, shingles, chickenpox
- Liquid form
- Valacyclovir
- No commercial liquid
- Acyclovir
- Yes, an oral suspension
- Generic
- Valacyclovir
- Yes
- Acyclovir
- Yes
Valacyclovir Valtrex | Acyclovir Zovirax | |
|---|---|---|
| How it works | Converted to acyclovir after absorption | Acts directly |
| Doses a day | Usually two or three | Usually two to five |
| Approved for | Cold sores, genital herpes, shingles, chickenpox in children | Genital herpes, shingles, chickenpox |
| Liquid form | No commercial liquid | Yes, an oral suspension |
| Generic | Yes | Yes |
Same medicine, different dosing
Because valacyclovir is absorbed so much better, it reaches the same levels of acyclovir in the body with fewer doses. For shingles, valacyclovir is taken three times a day, while acyclovir is taken five times a day. For cold sores, valacyclovir can be taken as two doses in a single day at the first tingle. Both work best started as early as possible in an outbreak.
Choosing between them
Valacyclovir is usually easier to take correctly, which matters because missed doses reduce the benefit. Acyclovir suits people who need a liquid, such as young children, and its tablets cost less each, though more are needed for a course. For long-term suppression of genital herpes, either can be taken daily.
Safety
Both are generally well tolerated. Doses are lowered in reduced kidney function, older adults are watched for confusion, and drinking plenty of fluids helps protect the kidneys, especially at high doses.
Cost
Both are generics. Compare the total price of the whole course, not the price per tablet, since acyclovir courses use more tablets.
Preventing spread
Neither medicine cures herpes, but daily suppressive treatment lowers the chance of passing genital herpes to a partner, alongside condoms and avoiding sex during outbreaks. Shingles blisters can pass chickenpox to people who have never had it or been vaccinated until the blisters crust over, and the shingles vaccine lowers the chance of shingles for adults 50 and older.
Questions for your prescriber
- How soon should I start treatment when an outbreak begins?
- Would daily suppression make sense for me?
- Does my kidney function change the dose?
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Sources
Written by the Script Unlock editorial team from the sources above. It is general information, not advice for you or your pet; your prescriber decides which medicine is right.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.