Valacyclovir vs Acyclovir: What’s the Real Difference?

If you’ve ever been prescribed an antiviral for a cold sore or genital herpes flare, you’ve probably heard the names valacyclovir and acyclovir. Both are proven to fight the same viruses, but they aren’t identical pills. Knowing how they differ can save you time, money, and unnecessary side effects.

How the drugs work

Acylovir is the older drug. It’s a nucleoside analog that tricks the virus into copying its DNA, then stops the copy process. You usually take it three to five times a day because the body clears it quickly. Valacyclovir is basically acyclovir with a little chemical makeover –‑ a valine ester that helps the gut absorb it better. After you swallow a valacyclovir tablet, your liver turns it into acyclovir, but the conversion lets you take the medicine just once or twice daily.

Because of the better absorption, valacyclovir reaches higher blood levels than the same dose of acyclovir. That’s why many doctors prefer it for severe outbreaks or when they want a simpler dosing schedule.

Effectiveness and dosing

Studies show both drugs reduce the duration of cold sores by about one day and lower viral shedding. Valacyclovir, however, tends to cut the outbreak length a little more when you follow the higher‑dose regimen (often 1 g twice daily for shingles, for example). For daily suppressive therapy, valacyclovir can be taken once a day, while acyclovir needs to be split into three doses.

Side‑effects are similar: mild headache, nausea, or fatigue. Because valacyclovir produces higher blood levels, you might notice these a bit more, but most people tolerate both drugs well.

Cost is another factor. Generic acyclovir is usually cheaper per pill, but you need more pills each day. Valacyclovir’s higher price can be offset by the lower pill count and fewer pharmacy trips.

When choosing, think about your lifestyle. If you travel a lot or hate taking meds several times a day, valacyclovir’s once‑or‑twice‑daily schedule is a win. If you’re on a tight budget and don’t mind three doses, acyclovir works just fine.

Both drugs require a prescription, so talk to your doctor about your outbreak frequency, kidney function, and any other meds you’re on. They’ll run a quick check and suggest the right dosage for you.Bottom line: valacyclovir offers convenience and slightly higher blood levels, while acyclovir gives you a budget‑friendly option with the same antiviral power. Knowing these basics helps you and your doctor pick the version that fits your needs best.