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Valacyclovir has been a decently popular medication over the last few years. In 2017, for example, more than four million prescriptions were issued. Considering how popular this drug is right now, it pays to know a little bit more about this medication, including how long valacyclovir stays in your system.

The FDA and the American Journal of Obstetrics Gynecology state the following information regarding valacyclovir half-life:

Mean effective half-life: The half-life for valacyclovir is short, about 30 minutes. However, it converts to acyclovir, which has a half-life of 2.5 to 3.3 hours in those with normal renal (kidney) function. 

Time to steady-state: 38 weeks for acyclovir

Mean accumulation ratio: No accumulation in those with healthy renal functioning 

Terminal phase half-life: 2.5 to 3.3 hours 

Valacyclovir has an oral bioavailability of  54.5% ± 9.1%. Valacyclovir is readily absorbed via the gastrointestinal tract and then converted to acyclovir. It is eliminated in urine and feces. 


What is the half-life of valacyclovir?

The half-life of valacyclovir is short because the body converts it to acyclovir. The half-life of the acyclovir is between 2.5 to 3.3 hours. 

How long does valacyclovir stay in your system?

Valtrex stays in the system for approximately 22 to 25 hours. However, the FDA reports it is detectable in urine for up to 96 hours (4 days) after the last dose. 

How long does it take for valacyclovir to get out of your system?

It can still be found in urine and feces 96 hours (4 days) after taking the drugs. 

How long does it take for valacyclovir to start working?

Most people will see results in two to three days.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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