Does Valacyclovir Make You Tired? Understanding Fatigue and Other Side Effects

October 7, 2025 •

2 min read

According to the FDA drug label, a study involving HIV-1 infected individuals showed that 8% reported fatigue while on valacyclovir, compared to 5% on a placebo, suggesting that yes, does valacyclovir make you tired? is a valid concern for some users. This article explores why this can happen, and what you can do about it.

Quick Summary

Valacyclovir can cause fatigue as a potential side effect, though it is more frequently reported in specific populations and generally considered mild. The risk increases with impaired kidney function, age, and higher dosages. Management involves staying hydrated, monitoring symptoms, and consulting a doctor for severe cases.

Key Points

Fatigue is a Known Side Effect: Tiredness is a reported side effect of valacyclovir, though typically mild to moderate in immunocompetent adults.
Higher Risk for Specific Groups: The risk of fatigue and more serious CNS effects is elevated in patients with HIV, impaired kidney function, or advanced age.
Dosage and Kidney Function Matter: Poor kidney function can lead to drug accumulation, increasing the likelihood of side effects, including severe fatigue and CNS issues. Dose adjustments are often necessary.
Management Strategies Exist: Staying well-hydrated, taking the medication with food, and ensuring adequate rest can help manage symptoms.
Consult Your Doctor for Concerns: If fatigue is persistent, severe, or accompanied by other neurological symptoms like confusion or dizziness, it is crucial to speak with a healthcare provider.

Understanding Valacyclovir and its Mechanism

Valacyclovir, commonly known by its brand name Valtrex, is an antiviral medication prescribed to treat infections caused by herpes viruses. These include cold sores (herpes labialis), shingles (herpes zoster), and genital herpes (herpes simplex). It functions by preventing the virus from multiplying within the body.

How Valacyclovir Works in the Body

Valacyclovir is a prodrug that is converted in the body into the active form, acyclovir. This conversion primarily occurs in the intestines and liver. Acyclovir then inhibits viral DNA polymerase, stopping viral replication. This process allows for less frequent dosing compared to acyclovir.

Why Valacyclovir Can Cause Fatigue

Fatigue is a reported side effect of valacyclovir, noted in both clinical studies and patient experiences. The underlying viral infection itself can contribute to fatigue, and in some individuals, valacyclovir may have central nervous system (CNS) effects that lead to drowsiness, particularly in those with risk factors.

Factors That Increase the Risk of Fatigue and Other CNS Effects

Certain individuals are more likely to experience fatigue and other CNS side effects from valacyclovir. These risk factors include impaired kidney function, advanced age, immunocompromised status, and using high dosages. Reduced kidney function can lead to higher drug levels, increasing the risk of severe fatigue, confusion, or hallucinations; dose adjustments are crucial in these cases. Older patients may be more susceptible due to changes in kidney function and metabolism. Studies show a higher fatigue rate in immunocompromised individuals, such as those with HIV, and rarely, severely immunocompromised patients can develop serious blood disorders causing extreme fatigue. Higher valacyclovir doses are linked to an increased risk of neurological side effects.

Comparison: Valacyclovir vs. Acyclovir

Valacyclovir and its active form, acyclovir, share similar side effect profiles but differ in administration. For details on the comparison of side effects and dosing, please refer to {Link: Dr.Oracle AI https://www.droracle.ai/articles/117293/side-effects-of-valacyclovir}.

Managing Valacyclovir-Induced Fatigue

Strategies to help manage fatigue while taking valacyclovir include staying hydrated, taking the medication with food, discussing dose timing with your doctor, and considering other potential causes of tiredness. For further management tips, consult {Link: Dr.Oracle AI https://www.droracle.ai/articles/117293/side-effects-of-valacyclovir}.

When to Contact a Healthcare Provider

While mild fatigue may occur, certain symptoms warrant medical attention. For guidance on symptoms requiring contact with a healthcare provider, see {Link: Dr.Oracle AI https://www.droracle.ai/articles/117293/side-effects-of-valacyclovir}.

Conclusion

Valacyclovir can cause fatigue, especially in certain patient groups. Managing fatigue involves proper hydration and monitoring symptoms. Severe fatigue or other concerning signs require medical consultation. For a more detailed conclusion, refer to {Link: Dr.Oracle AI https://www.droracle.ai/articles/117293/side-effects-of-valacyclovir}.

Potential Outbound Link

For more information on neurological effects linked to valacyclovir, particularly in patients with kidney disease, refer to relevant research.

Comparison Table

For a detailed comparison table of Valacyclovir and Acyclovir, including oral bioavailability and side effects, please see {Link: Dr.Oracle AI https://www.droracle.ai/articles/117293/side-effects-of-valacyclovir}.

Frequently Asked Questions

The most common side effects of valacyclovir include headache, nausea, abdominal pain, and fatigue. These effects are typically mild and may resolve on their own within a few days or weeks.

Fatigue is not common for everyone. In clinical studies involving immunocompetent adults, it is not listed among the most common adverse reactions. However, it was reported in 8% of HIV-1 infected subjects in one study.

To reduce tiredness, ensure you stay well-hydrated throughout the day. Taking the medication with food can also help minimize stomach upset, which can contribute to a feeling of being unwell. If tiredness is severe, your doctor may evaluate for other causes or consider a dosage adjustment.

Mild side effects like fatigue may only last a few days to a couple of weeks. If they persist or worsen, you should consult your doctor to determine if the medication or another factor is the cause.

Yes, although rare, valacyclovir can cause more serious central nervous system (CNS) effects, especially in older adults or those with kidney problems. These can include confusion, agitation, and hallucinations and require immediate medical attention.

Yes, older adults and those with pre-existing kidney conditions are at a higher risk of experiencing side effects from valacyclovir, including CNS effects. For these populations, careful dose adjustment is often necessary.

Valacyclovir can be taken with or without food. However, for some individuals, taking it with a meal or snack can help reduce common gastrointestinal side effects like nausea or stomach pain, which can contribute to a feeling of being unwell.