NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated July 13, 2026

Acyclovir

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

A nucleoside analog antiviral that is the prototype agent for herpes virus infections. Active against herpes simplex virus types 1 and 2 (HSV-1, HSV-2) and varicella-zoster virus (VZV). Used for genital herpes (initial and recurrent episodes, chronic suppression), herpes zoster (shingles), varicella (chickenpox), herpes encephalitis (IV), and neonatal herpes (IV). Requires conversion to the active form by viral thymidine kinase, providing selective toxicity.

Evidence tier
Strong
Indexed sources
10 1987–2025
Interactions
0
Category
Prescription
Read the sources → Compare profiles
Publication status

Exploratory record, not a reviewed medical publication.

See the editorial and medical-review policies for the publication gate.

This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

A nucleoside analog antiviral that is the prototype agent for herpes virus infections. NutriStack rates the supporting evidence as strong. Common adult dosing is Genital herpes initial: 400 mg TID or 200 mg 5x/day x 7-10 days; suppressive: 400 mg BID; herpes zoster: 800 mg 5x/day x 7-10 days; IV encephalitis: 10 mg/kg every 8 hours x 14-21 days (as prescribed by your physician), though a prescriber sets the actual dose. This profile indexes 10 sources.

What it's good for
  • Treats primary and recurrent genital herpes (HSV-1, HSV-2)8,9
  • Chronic suppressive therapy for recurrent genital herpes
  • Treats herpes zoster (shingles)9,8
  • Treats varicella (chickenpox) in high-risk patients
  • IV formulation for herpes encephalitis and neonatal herpes8,3
What to watch for
  • Nausea and vomiting
  • Diarrhea
  • Headache
  • Known hypersensitivity to acyclovir or valacyclovir10,1
  • Severe renal impairment without dose adjustment4

The bottom line

Evidence rating strong. Most-documented uses: treats primary and recurrent genital herpes (hsv-1, hsv-2), chronic suppressive therapy for recurrent genital herpes, treats herpes zoster (shingles). 10 sources indexed (1987–2025), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

A prodrug (acyclic guanosine analog) that requires three phosphorylation steps for activation. Viral thymidine kinase (encoded by HSV/VZV) performs the first phosphorylation to acyclovir monophosphate, this step is ~3000x more efficient in virus-infected cells, providing selectivity. Cellular kinases then convert it to the active triphosphate form. Acyclovir triphosphate competitively inhibits viral DNA polymerase and, once incorporated into the growing DNA chain, acts as a chain terminator because it lacks the 3'-hydroxyl group needed for subsequent nucleotide addition.

Class
Nucleoside Analog Antiviral
Dosing

Dosing & protocol.

Common range
Genital herpes initial: 400 mg TID or 200 mg 5x/day x 7-10 days; suppressive: 400 mg BID; herpes zoster: 800 mg 5x/day x 7-10 days; IV encephalitis: 10 mg/kg every 8 hours x 14-21 days (as prescribed by your physician)
Recommended form
Oral capsules, tablets, suspension; IV for severe/CNS infections; topical cream

Oral bioavailability is low (15-30%) and decreases with increasing dose. Requires frequent dosing (3-5 times daily for oral). Can be taken with or without food. Maintain adequate hydration to prevent crystalluria, especially with IV formulation.4

Safety

Full safety detail.

Side effects

  • Nausea and vomiting
  • Diarrhea
  • Headache
  • Malaise
  • Renal toxicity/crystalluria (especially IV, ensure adequate hydration and slow infusion)
  • Neurotoxicity (tremor, confusion, especially in renal impairment)

Contraindications

  • Known hypersensitivity to acyclovir or valacyclovir10,1
  • Severe renal impairment without dose adjustment4
  • Dehydration (increased risk of renal crystalluria)
  • Concurrent nephrotoxic drugs without monitoring6
Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Randomized controlled trials

1

Reviews & position papers

5

Reference material

4
FAQ

Common questions.

Quick answers about Acyclovir, drawn from the data on this page.

What is Acyclovir?

A nucleoside analog antiviral that is the prototype agent for herpes virus infections. Active against herpes simplex virus types 1 and 2 (HSV-1, HSV-2) and varicella-zoster virus (VZV). Used for genital herpes (initial and recurrent episodes, chronic suppression), herpes zoster (shingles), varicella (chickenpox), herpes encephalitis (IV), and neonatal herpes (IV). Requires conversion to the active form by viral thymidine kinase, providing selective toxicity.

What is Acyclovir used for?

Commonly cited benefits of Acyclovir include: Treats primary and recurrent genital herpes (HSV-1, HSV-2); Chronic suppressive therapy for recurrent genital herpes; Treats herpes zoster (shingles); Treats varicella (chickenpox) in high-risk patients; IV formulation for herpes encephalitis and neonatal herpes. NutriStack rates the overall evidence as strong.

What is a typical dose of Acyclovir?

A typical adult dose of Acyclovir is Genital herpes initial: 400 mg TID or 200 mg 5x/day x 7-10 days; suppressive: 400 mg BID; herpes zoster: 800 mg 5x/day x 7-10 days; IV encephalitis: 10 mg/kg every 8 hours x 14-21 days (as prescribed by your physician). The commonly recommended form is Oral capsules, tablets, suspension; IV for severe/CNS infections; topical cream. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Acyclovir?

Reported side effects include nausea and vomiting, diarrhea, headache, malaise, renal toxicity/crystalluria (especially iv, ensure adequate hydration and slow infusion), neurotoxicity (tremor, confusion, especially in renal impairment). This is educational information; check with a healthcare professional before use.

How strong is the evidence for Acyclovir?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

Use this with your stack

Acyclovir in NutriStack.

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