Is Long-Term Use of Valacyclovir Bad? A Comprehensive Safety Review

October 9, 2025 •

2 min read

In the United States, research from 2015–2016 showed that 47.8% of people aged 14–49 had Herpes Simplex Virus Type 1 (HSV-1). This prevalence leads many to ask: is long-term use of valacyclovir bad for managing the virus? This article examines the evidence.

Quick Summary

Long-term valacyclovir use is generally considered safe and well-tolerated for suppressing herpes in people with normal kidney function. Key risks, though rare, involve kidney and neurological effects, particularly in the elderly or dehydrated.

Key Points

Generally Safe: For most people with healthy kidneys, long-term valacyclovir use is considered safe and well-tolerated.
Kidney Health is Key: The most significant risk involves the kidneys; staying hydrated is crucial to prevent potential damage.
Reduces Outbreaks & Transmission: Daily suppressive therapy effectively reduces the frequency of herpes outbreaks and can cut transmission risk to a partner by about half.
At-Risk Groups: The elderly and individuals with pre-existing kidney disease are at a higher risk for side effects and require careful monitoring or dose adjustments.
Convenient Dosing: Valacyclovir is often preferred for long-term therapy due to its convenient dosing schedule compared to older antivirals like acyclovir.
Consult a Doctor: Long-term suppressive therapy should always be managed by a healthcare provider to monitor for side effects and periodically assess the need for continued use.

Suppressive Therapy: Benefits and Goals

Taking valacyclovir regularly can reduce the frequency of herpes outbreaks and lower the risk of transmitting the virus. Studies indicate it can reduce HSV-2 transmission by approximately 50% in heterosexual, monogamous couples. This therapy can significantly improve patients' quality of life by reducing the impact of recurrent outbreaks.

Is Long-Term Use of Valacyclovir Bad for You?

Long-term use of valacyclovir is generally considered safe for most people with normal kidney function. Studies lasting up to 20 months show it is as safe as short-term use, with mild side effects like headache and nausea being infrequent. Serious side effects have been rare and occurred at a similar rate to placebo.

Potential Risks and Side Effects

The main concern with long-term valacyclovir use is the potential for kidney damage. Factors increasing this risk include dehydration, existing kidney disease, elderly patients, and combining with other kidney-damaging drugs.

Other Rare but Serious Side Effects

Rarely, neurological effects like confusion or seizures can occur, particularly in older adults or those with kidney problems. Thrombotic Microangiopathy (TMA) is a very rare blood disorder observed mainly in severely immunocompromised patients.

Comparison of Antiviral Medications

Valacyclovir is one of several oral antivirals used for herpes management.


Feature	Valacyclovir (Valtrex)	Acyclovir (Zovirax)	Famciclovir (Famvir)
Absorption	~55% (converts to acyclovir)	15-30%	~77% (converts to penciclovir)
Suppressive Dosing	Often once daily	Typically 2-3 times daily	Often twice daily
Primary Uses	HSV-1, HSV-2, Shingles, Chickenpox	HSV-1, HSV-2, Shingles	Shingles, also HSV
Common Side Effects	Headache, nausea, abdominal pain	Nausea, vomiting, diarrhea, headache	Headache, nausea

Valacyclovir's better absorption allows for more convenient dosing compared to acyclovir. Famciclovir is another option, with some evidence suggesting valacyclovir is slightly better for suppressing genital herpes.

Conclusion

For most healthy individuals, long-term valacyclovir use is not considered harmful, with the benefits of reducing outbreaks and transmission generally outweighing potential risks. The main risk is kidney damage, which can be minimized by staying hydrated and through careful management in at-risk groups like the elderly or those with existing kidney issues. Regular medical consultation is important for monitoring safety and effectiveness. The need for continued therapy should be reviewed with a doctor periodically.

Visit the American Sexual Health Association for more information on herpes management.

Frequently Asked Questions

Yes, studies have shown that daily valacyclovir is generally safe and well-tolerated for periods extending beyond one year in individuals with normal kidney function.

While rare, kidney damage is a potential risk, especially in older adults, those with pre-existing kidney problems, or those who are dehydrated. Maintaining adequate hydration significantly lowers this risk.

A healthcare professional will determine the appropriate dosage based on individual factors, including the type of herpes being suppressed and the patient's kidney function.

If you stop suppressive therapy, the frequency and severity of your herpes outbreaks may return to what they were before you started the medication. You should discuss stopping with your healthcare provider.

Resistance to acyclovir (the active form of valacyclovir) is very rare in immunocompetent individuals (less than 0.5%) but can be slightly more common (around 5%) in those who are immunocompromised.

Valacyclovir is often preferred because its higher bioavailability allows for less frequent dosing, whereas acyclovir typically needs to be taken more often for suppression.

The most commonly reported side effects are generally mild and include headache, nausea, and abdominal pain.

Yes, while daily valacyclovir significantly reduces the risk of transmission (by about 50%), it does not eliminate it completely. Safer sex practices, such as using condoms, are still recommended.