Valacyclovir vs. acyclovir: How are they different?

Valacyclovir and acyclovir are prescription antiviral medications used to treat various herpes infections, including cold sores, genital herpes, and chickenpox. 

Although they’re used for similar purposes, valacyclovir is absorbed by the body more quickly and requires less frequent dosing than acyclovir.

Here are the available forms of each medication:

• Valacyclovir (Valtrex)
  • oral tablets 
• Acyclovir (Zovirax, Sitavig)
  • oral tablets
  • oral capsules
  • oral suspension (liquid)
  • topical cream 
  • topical ointment
  • injection (intravenous [IV])

How are the dosages for valacyclovir and acyclovir different?

The main difference is in how often you need to take the medication.

Although valacyclovir and acyclovir both treat herpes virus infections, valacyclovir requires fewer doses per day because it has better bioavailability. Bioavailability refers to the amount of medication that enters your bloodstream and actively affects your body.

The following lists indicate dosage differences for valacyclovir and acyclovir. All dosages are in grams (g), milligrams (mg), or mg per kilogram (kg). (For reference, 1 kg is about 2.2 pounds.)

• Genital herpes (initial outbreak):
  • valacyclovir: 1 g, taken orally twice per day for 7 to 10 days
  • acyclovir: 400 mg, taken orally three times per day for 7 to 10 days
• Genital herpes (recurrent episodes):
  • valacyclovir: 500 mg, taken orally twice per day for 3 days
  • acyclovir: 400 mg, taken orally three times per day for 5 days.
• Chickenpox (varicella):
  • valacyclovir: 20 mg/kg, taken three times per day for 5 days
  • acyclovir: 800 mg, taken four times per day for 5 days
• Cold sores:
  • valacyclovir: 2 g every 12 hours for 1 day
  • acyclovir: 200 mg, taken five times per day for 5 days

The prescribed dosages of valacyclovir and acyclovir may vary depending on individual factors and the severity of the condition. 

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What happens if I switch from valacyclovir to acyclovir?

When switching from acyclovir to valacyclovir, there may be a difference in the dosing schedule. You may also notice a difference in how effectively acyclovir helps manage symptoms. 

Valacyclovir has higher bioavailability than acyclovir, so you don’t have to take it as frequently.

Acyclovir, while effective, requires more frequent doses due to its shorter half-life and lower bioavailability. This frequent dosing can be a disadvantage for some people.

What are the side effects of valacyclovir vs. acyclovir?

The side effects of valacyclovir and acyclovir are similar. Commonly reported side effects include:

• headache
• nausea
• vomiting
• abdominal pain
• dizziness

Rare but severe nervous system side effects, such as agitation and confusion, may occur with valacyclovir and acyclovir. These side effects are more common in people with kidney disease who do not receive an appropriately adjusted dose. 

If you experience any ongoing or severe side effects while taking either medication, talk with your doctor.

Is valacyclovir or acyclovir better for a cold sore?

Valacyclovir is the recommended medication for cold sores. An older study found that a high dose, short-duration course of early valacyclovir treatment can reduce healing time by about a day compared to acyclovir.

However, valacyclovir and acyclovir are both effective treatments for cold sores. The choice between them often depends on personal preference and cost. Consider talking with your doctor about which option is better for you.

Is there a difference in the cost between valacyclovir and acyclovir?

Yes, valacyclovir generally costs more than acyclovir. This is because it’s newer and offers the convenience of less frequent dosing. Both medications are generic drugs, and this helps reduce costs. They both come in brand names, but these are likely to cost more.

To find discounts and compare prices with Optum Perks coupons, visit the coupon pages for valacyclovir and acyclovir. You can also consider talking with your doctor or insurance provider for further guidance.

Need a refill for valacyclovir (Valtrex)? You may be able to get an online prescription through Optum Perks in as little as 15 minutes. Learn more here.

Summary

Valacyclovir and acyclovir are effective antiviral medications that healthcare professionals prescribe to treat herpes virus infections. Valacyclovir requires less frequent dosing than acyclovir due to better absorption in the body.

While valacyclovir may be more convenient, it often costs more than acyclovir. The medications have similar side effects, and switching between them can be done under medical supervision.

For cold sores, valacyclovir’s reduced dosing schedule usually makes it the more convenient option.