Can acyclovir cause seizures?
Yes. Acyclovir can cause seizures in some people, especially at higher drug exposures.
Seizures are a known rare neurologic adverse effect of acyclovir. The risk is higher when acyclovir builds up in the body, most often because of reduced kidney function (the drug is cleared through the kidneys) or if doses are too high for that level of kidney function. [1]
Why would acyclovir lead to seizures?
Seizures can occur when acyclovir reaches high blood levels. This can happen with:
- Kidney impairment or dehydration, which reduces drug clearance.
- Receiving doses not adjusted to kidney function.
- High-dose or intravenous use (commonly associated with greater risk than standard oral use).
High drug concentrations can affect the nervous system and trigger neurologic symptoms, including confusion, tremors, and, rarely, seizures. [1]
Who is at higher risk?
People most likely to experience serious neurologic side effects include those with:
- Chronic kidney disease or acute kidney injury
- Older age (often linked with lower kidney function)
- Dehydration
- Higher-than-standard dosing or faster-than-recommended infusion rates (for IV acyclovir)
If you or the patient has kidney problems, clinicians typically check kidney function and adjust the dose to lower seizure risk. [1]
What symptoms should prompt urgent care?
Seek urgent medical attention if acyclovir use is followed by:
- Seizure activity
- New confusion, severe agitation, hallucinations
- Unusual tremor, drowsiness, or trouble staying awake
Seizures require emergency evaluation, because additional issues (such as dehydration, kidney injury, electrolyte problems, or the underlying infection) can also contribute. [1]
What should you do if seizures happen while taking acyclovir?
If seizures occur, acyclovir should be stopped and medical care obtained immediately. Treatment is supportive and may include seizure management and correcting contributing problems like kidney dysfunction and dehydration. Dose adjustment after recovery depends on kidney function and the reason for acyclovir. [1]
Does this happen with oral or IV acyclovir?
Seizures are reported with acyclovir overall, but the risk is generally higher with systemic exposures that lead to higher blood levels, such as IV therapy or inappropriate dosing in people with impaired kidney function. Oral acyclovir can also contribute if kidney clearance is reduced. [1]
---
Sources
- https://www.drugs.com/sfx/acyclovir-side-effects.html