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Peds Calc

Pediatric Reference

Acyclovir Side EffectsComprehensive Pediatric Safety Guide

Acyclovir is generally well tolerated; GI upset and headache are the most frequent pediatric complaints. Serious renal or neurologic effects are rare and usually linked to dehydration or impaired kidney function.

4 Categories
7 Clinical Sources
Evidence-Based
Back to Acyclovir Overview

Essential Information

1

Encourage extra fluids to prevent kidney irritation.

2

Most side effects are mild and improve as the infection clears.

3

Call urgently for reduced urine output, confusion, or severe rash.

Clinical Overview

Hydration and renal monitoring in high-risk children mitigate most adverse effects.

Side Effect Categories

4 Systems

Gastrointestinal

2 documented effects

Total Sources: 3

Nausea

Incidence: Common
Onset: Early in therapy
mild
2 sources
Duration

Not specified

Management

Give with food and small frequent sips of fluids.

Monitoring Guidelines

Call if persistent vomiting or signs of dehydration.

2 clinical sources• PubMed • Clinical Guidelines • FDA

Diarrhea

Incidence: Less common
Onset: Not specified
mild
1 sources
Duration

Not specified

Management

Supportive care, hydration, BRAT-style diet if tolerated.

Monitoring Guidelines

Call for bloody stools, high fever, or dehydration.

1 clinical sources• PubMed • Clinical Guidelines • FDA

Neurologic

2 documented effects

Total Sources: 2

Headache

Incidence: Common
Onset: Not specified
mild
1 sources
Duration

Not specified

Management

Use age-appropriate analgesics as directed; maintain hydration.

Monitoring Guidelines

Monitor for symptom escalation or new adverse effects.

1 clinical sources• PubMed • Clinical Guidelines • FDA

Dizziness or confusion

Incidence: Rare
Onset: Usually in renal impairment or high serum levels
serious
1 sources
Duration

Not specified

Management

Stop medication and seek urgent medical evaluation.

Monitoring Guidelines

Watch for new confusion, agitation, or hallucinations—especially in renal disease.

1 clinical sources• PubMed • Clinical Guidelines • FDA

Renal

1 documented effect

Total Sources: 1

Crystalluria/renal dysfunction

Incidence: Rare
Onset: Usually with dehydration or rapid IV dosing
serious
1 sources
Duration

Not specified

Management

Stop drug, ensure hydration, obtain labs per clinician.

Monitoring Guidelines

Monitor urine output; call for reduced urination or flank pain.

1 clinical sources• PubMed • Clinical Guidelines • FDA

Skin

1 documented effect

Total Sources: 1

Rash

Incidence: Uncommon
Onset: Not specified
variable
1 sources
Duration

Not specified

Management

Stop medication and contact clinician; evaluate for allergy.

Monitoring Guidelines

Monitor for symptom escalation or new adverse effects.

1 clinical sources• PubMed • Clinical Guidelines • FDA

Parent Communication Guide

Age-Appropriate Explanations

Infants (0-12 months)

For babies taking Acyclovir, watch for signs of side effects. This medication is generally well-tolerated in infants when used as directed.

Toddlers (1-3 years)

This medicine helps fight the germ causing your sores. Sip water often.

Children (4-12 years)

Acyclovir helps slow down the virus so you heal faster. Drinking water keeps your kidneys happy.

Adolescents (13+ years)

Stay on schedule and hydrate to protect your kidneys while on this antiviral.

Common Parent Concerns

Q: My child is nauseated

A: Give doses with a light snack and keep fluids flowing.

When to validate: Call if vomiting persists or your child cannot keep fluids down.

Q: Worried about kidney effects

A: Kidney issues are uncommon with good hydration and correct dosing.

When to validate: Call if urine output drops or there is flank/back pain.

Clinical Decision Support

Severity Assessment Framework

Clinical assessment framework for Acyclovir adverse effects using standardized severity grading.

Mild
Indicators: Minimal symptoms, No functional impairment, Patient comfortable continuing
Action: Continue medication with supportive care and routine monitoring
Moderate
Indicators: Noticeable symptoms, Some functional impact, Patient/family concerned
Action: Consider dose adjustment, increase monitoring frequency, provide supportive care
Severe
Indicators: Significant symptoms, Functional impairment, Quality of life affected
Action: Consider discontinuation, evaluate alternatives, close clinical follow-up

Treatment Decision Guidelines

Immediate Discontinuation

  • Severe allergic reactions
  • Life-threatening adverse effects
  • Signs of toxicity

Consider Alternatives

  • Persistent moderate side effects
  • Inadequate therapeutic response
  • Patient/family preference

Dose Modification

  • Mild side effects with good efficacy
  • Age-related sensitivity
  • Drug interaction concerns

Clinical References

Acyclovir Oral Suspension — DailyMedU.S. National Library of Medicine (2025)Label
Acyclovir — MedlinePlusMedlinePlus (2025)Drug Information
Aciclovir for viral infectionsMedicines for Children (2024)Patient guidance

Frequently Asked Questions

Parent and clinician concerns about Acyclovir