Acyclovir: Uses, Side Effects, and How to Take It
Acyclovir is an antiviral medicine that helps reduce the severity and duration of certain infections caused by the herpes virus family. It is used for conditions such as cold sores, genital herpes, chickenpox, shingles, and some eye infections.
Acyclovir can shorten or reduce symptoms of certain herpes infections, but it does not cure the virus or stop future outbreaks. Take it exactly as prescribed and ask a doctor or pharmacist when unsure.
Key facts at a glance
- ATC
- J05AB01
- Generic
- Acyclovir
- Class
- antiviral
- Brands
- Zovirax
- Availability
- rx
- Pregnancy
- B
- Lactation
- caution
- Half-life (h)
- 3
- Onset (min)
- 60
- Duration (h)
- 8
- Routes
- oral, iv, topical
- Forms
- capsule, injection, cream
- Regions
- CN, US, EU, JP
- Monitoring
- renal-function, hydration
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 800mg five times daily
- Maximum
- consult physician
- Frequency
- every 4 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 200mg five times daily
- Maximum
- consult physician
- Frequency
- every 4 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg three times daily
- Maximum
- consult physician
- Frequency
- every 8 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
9 groupspregnancy
first trimesterno specific adjustment
use only if benefits outweigh potential risks
standard prenatal care
Use with caution and monitor for adverse effects.
pregnancy
third trimesterno specific adjustment
use for treatment of active infection or prophylaxis
standard prenatal care
Use with caution and monitor for adverse effects.
lactation
nno adjustment needed
compatible with breastfeeding
no specific monitoring
geriatric
nadjust based on renal function
monitor renal function and adjust dose accordingly
monitor renal function
Use with caution and monitor for adverse effects.
pediatric_age
neonatesweight-based dosing, reduce in renal impairment
use with caution in neonates, especially premature
monitor renal function and neurological status
Use with caution and monitor for adverse effects.
pediatric_age
childrenweight-based dosing
oral and intravenous formulations available for pediatric use
standard pediatric monitoring
renal_impairment
mildreduce dose for IV formulation
monitor renal function, adjust dose as needed
monitor creatinine clearance
Use with caution and monitor for adverse effects.
renal_impairment
severesignificant dose reduction required
reduce dose to 200-400mg every 12-24 hours depending on severity
close monitoring of renal function and drug levels
Use with caution and monitor for adverse effects.
hepatic_impairment
nno significant adjustment required
no dose adjustment typically needed
standard monitoring
Statistics and clinical data
FDA approval year
Initial FDA approval for Acyclovir
Drug class
Pharmacological classification
Common uses
Primary therapeutic indications
Mechanism of action
Pharmacological mechanism
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 22, 2026. · Read our editorial policy