No, you should not take expired Valtrex. Though it is unlikely to cause harm, its effectiveness is not guaranteed beyond its expiration date. As a result, it may not effectively treat your symptoms.
Valtrex is used to treat herpes simplex virus (HSV), herpes zoster (shingles), and herpes labialis (cold sores). It does not cure herpes, but it can treat the symptoms, reducing the patient’s discomfort. (Learn More)
The exact nature of expired medications is a topic in need of further study. However, medicines are only guaranteed to be potent, effective, and safe up to their expiration dates. Beyond that, their potency cannot be guaranteed and, although admittedly rare, they may even be dangerous. (Learn More)
Most drugs are marked to “expire” within two to three years, and Valtrex is no exception. (Learn More) Overall, it is unwise to take medicine outside of the parameters under which it was tested and approved by the relevant authorities. (Learn More)
What Is Valtrex?
Valtrex is the brand name for the drug valacyclovir. It is used to fight herpes virus infections, including herpes labialis (cold sores), herpes zoster (shingles), and herpes simplex (HSV/genital herpes). It is also sometimes used to prevent cytomegalovirus (CMV), another member of the Herpesvirales order, from infecting a person after organ transplants.
Valtrex cannot cure shingles or genital herpes. It can treat these conditions and reduce their more uncomfortable symptoms, which it does by converting to the drug acyclovir while in the body.
It is important to also understand Valtrex does not prevent you from spreading herpes. You still need to practice safe sex and keep partners informed of any potential risks.
While you should always follow your specific instructions as outlined by your doctor, Valtrex is usually taken at 1000 mg three times a day for seven days for shingles; at 500 mg twice a day for HSV; and 500 mg four times a day for up to 90 days for CMV.
Doses may be adjusted for those with weakened immune systems, those with kidney problems, the elderly, and children. The pills come in 500 mg doses.
What Are the Risks of Expired Valtrex?
Discussing the risks of expired medication is actually more complicated than some might think. The expiration date of medications is chosen somewhat arbitrarily and does not necessarily represent when a medication loses potency or might be dangerous. It instead represents when medication is no longer guaranteed by law and the manufacturer to function as intended.
There are essentially two risks associated with expired medication. The most common issue is that the medication may have lost potency. Put simply, 500 mg of expired Valtrex will not necessarily have the strength of a new batch of Valtrex.
Knowing exactly how potent an expired medication is requires lab testing. Since this is cost- prohibitive for average patients, there’s no way for you to know if your expired Valtrex will have reduced effectiveness.
The second risk, and much rarer, is that an expired medication might become dangerous over time. According to Harvard Health Publishing, the only medication readily associated with potentially becoming dangerous over time is tetracycline. However, it is still worth noting since many medications are not well studied past their expiration dates, Valtrex included.
You are unlikely to be seriously harmed by taking expired Valtrex, but again, the drug may lose potency over time. Since the complications associated with many of the conditions Valtrex treats can be serious if improperly treated, it is a good idea to make sure your medication is reliable.
You should not take expired Valtrex without talking with your doctor.
How Long Does Valtrex Last?
Valtrex, like most drugs, will be set to expire some time between two to four years after purchase. As discussed above, exactly how long it lasts beyond that is a question without a well-researched answer.
Drug manufacturers have little incentive to test their drugs potency beyond the legal requirement. As a matter of fact, it is in their best interest to not do so as testing potency beyond the norm will take time and money. It is more profitable for companies to instead make new medications and market products. Nearly every drug manufacturer is a for-profit organization.
It is a bad idea to rely on a medication that is expired. After a period of one to two years beyond its expiration date, it should probably be tested to make sure the potency is still reliable.
More Research Required
With very few exceptions (tetracycline, nitroglycerin, insulin, and liquid antibiotics), medications remain potent and safe beyond their listed expiration date. Some drugs reportedly maintain most of their potency even decades after their marked expiration date.
Present legal policy and research are a bit behind when it comes to how the expiration dates of drugs are determined. At the same time, drugs can lose potency and can even become dangerous over time (although this is rare). For these reasons, take your medication as intended and do not take expired medicine without talking with your doctor.
Valacyclovir. PubChem Database.
Valacyclovir (Oral Route): Description and Brand Names. (February 1, 2019). Mayo Foundation for Medical Education and Research (MFMER).
That Drug Expiration Date May Be More Myth Than Fact. (July 18, 2017). NPR.
Drug Expiration Dates — Do They Mean Anything? (August 13, 2018). Harvard University.
Valtrex Tablets. (June 21, 2017). Medsafe.
Cytomegalovirus (CMV) and Congenital CMV Infection. (June 6, 2018). Centers for Disease Control and Prevention.