How long does Valtrex stay in your system?

Valtrex has an average half-life of 2.5 to 3.3 hours in patients with healthy kidney function, meaning it stays in the system for around 5 to 6.6 hours, as reported by RxList. The half-life of Valtrex in patients with impaired kidney function is 14 hours on average, meaning it stays in the system for around 28 hours.

Valtrex is a brand name for valacyclovir, which is an antiviral drug used to treat several types of the herpes virus, including cold sores, genital herpes, shingles and others, according to WebMD. The drug's elimination time is determined by the patient's kidney function and age, with younger patients eliminating the drug slightly faster than geriatric patients, as reported by RxList.