Cicloviral

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Cicloviral

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Medically reviewed

Marina Burgos

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Cicloviral

Property Description
Active Ingredient Aciclovir (Acyclovir)
Form Tablet, Capsule, Suspension, Cream, IV Solution
Pharmacological Class Antiviral
Common Use Managing herpesvirus infections
Origin Synthetic Nucleoside Analogue

What Type of Medicine is Cicloviral and What is it Made Of?

Cicloviral is an antiviral medicine with the single active ingredient Aciclovir (Acyclovir). This drug is classified as a synthetic purine nucleoside analogue. Its structure is chemically manufactured to mimic natural building blocks, giving it high inhibitory activity against DNA viruses.

The medicine is recognized globally as a foundational treatment. The single-ingredient product is available in diverse dosage forms, including oral forms (tablets and capsules), topical forms (creams), and a sterile solution for intravenous injection. These preparations allow for administration via oral, topical, or parenteral routes, ensuring comprehensive coverage for various infection presentations.


Understanding the General Purpose of Cicloviral

The general purpose of Cicloviral is to slow the spread and growth of targeted herpes viruses within the body. Its highly selective mechanism ensures its activity is largely confined to cells that have been infected by the target virus, which is clinically recognized for minimizing disruption to the processes of healthy cells.

The drug is functionally activated only inside the infected cell, where it acts as a faulty building block to directly interfere with viral DNA synthesis, preventing the virus from completing its replication cycle. Aciclovir has been the standard antiviral therapy in several manifestations of herpes simplex virus infection, representing a major therapeutic advance. This action assists the body’s natural defenses in bringing the viral condition under control.

Regulatory References

  1. NIH StatPearls Antiviral Review

What side effects are possible with Cicloviral?

Possible side effects and safety information

Cicloviral (Aciclovir) has a documented safety profile derived from government regulatory documents, categorized by frequency and system-organ class. This information describes the adverse reactions that have been officially reported, without providing clinical advice or usage instructions.


Adverse Reaction Classifications

Side effects are officially classified according to their documented frequency:

  • Common (may affect up to 1 in 10 people): Headache, dizziness, nausea, vomiting, diarrhea, abdominal pains, fatigue, fever, pruritus (itching), and rashes (including photosensitivity).
  • Uncommon: Urticaria (hives) and accelerated diffuse hair loss.
  • Rare and Very Rare: These include serious documented reactions such as acute renal failure, hepatitis, jaundice, anaphylaxis, and severe neurological effects (e.g., convulsions, encephalopathy, coma). Adverse events are grouped by System-Organ Class, affecting the nervous system, gastrointestinal tract, skin, and renal/urinary system.

Regulatory Safety Considerations

The official labeling includes specific safety constraints and notes for certain patient groups:

  • Hydration: Maintaining adequate hydration is required to reduce the risk of potential renal toxicity, particularly with high oral or intravenous administration, as noted in regulatory texts.
  • Population-Specific Cautions: The labeling notes an increased potential for neurological side effects in elderly patients and those with renal impairment; monitoring for these effects is advised in these groups.
  • Contraindication: The medicine should not be used in individuals with a known hypersensitivity to aciclovir, valaciclovir, or any components of the formulation.

Neurological effects, when they occur, are generally documented as being reversible upon discontinuation of the medicine.

Overdose and Emergency Response

Overdose and when to seek help

This information is based strictly on the official content documented in government regulatory prescribing information for Aciclovir (Cicloviral).


Documented Overdose Manifestations

Overdose may present with Central Nervous System (CNS) effects, which include agitation, confusion, hallucinations, lethargy, tremor, and somnolence. Gastrointestinal symptoms such as nausea and vomiting are also documented. The primary life-threatening complication is Acute Renal Failure, which may result from the precipitation of the drug in the renal tubules and has been associated with severe outcomes.

Official Emergency Actions

Element Official Regulatory Description
Immediate Action Required Seek emergency medical attention immediately for suspected overdose.
When to Call Emergency Services Urgent help must be sought if the affected person collapses, has a seizure, or cannot be awakened.
Supportive Management Treatment is primarily symptomatic and supportive care. Haemodialysis is documented as a procedural option that may be considered for drug removal.
Antidote Availability No specific antidote is known for Aciclovir overdose.

Overdose risk and severity are noted to be increased in elderly patients and individuals with reduced kidney function (renal impairment). Regulatory authorities require close observation of the patient and monitoring of fluid and electrolyte balance in overdose situations.

Therapeutic Uses of Cicloviral

What Cicloviral Treats: Main Uses and Benefits

Cicloviral is commonly used across therapeutic domains where additional symptomatic support is needed, addressing conditions characterized by periods of heightened symptoms. This medication is commonly used to help manage discomfort and supports the healing of sores associated with viral infections. It is applied in the acute treatment of conditions such as Herpes Simplex (including cold sores and genital herpes), Herpes Zoster (Shingles), and severe infections like Herpes Simplex Encephalitis.

The medication helps address symptom clusters that may become intense or disruptive, providing support that eases the overall symptom burden of localized pain, burning, tingling, and the formation of blisters and sores. In chronic management, it is used for managing the frequency of future manifestations, contributing to improved comfort during symptomatic periods.

“This intervention provides support that helps ease the overall symptom burden and may assist in easing the severity and progression of these acute, challenging phases.”

Quick Fact: Supports Management of Viral Skin Lesions and Neuropathic Discomfort

Regulatory References

  1. NIH MedlinePlus overview of Acyclovir

Eligibility and Restrictions for Use

Who Can and Cannot Use Cicloviral?

The population eligibility for Cicloviral (Aciclovir) is defined by specific conditions outlined in regulatory documents, identifying who can use the medicine, who must not, and who requires restricted use.

Absolute Contraindications

Cicloviral is contraindicated for any individual with a known history of hypersensitivity or allergic reaction to the active substance Aciclovir or to Valaciclovir (a related antiviral drug). Contraindication also extends to hypersensitivity to any inactive ingredient (excipient) in the specific formulation.


Condition-Based Restrictions

Population/Condition Regulatory Status
Renal Impairment Restricted/Conditional Use. Dosage adjustment is mandatory due to the drug’s clearance via the kidneys.
Geriatric Patients Conditional Use. Requires evaluation for potential age-related reduction in renal function.
Pregnancy/Lactation Restricted Use. Permitted only when the potential benefits outweigh the risks; caution is advised.

Age-Group Eligibility

Use is established in the adult population. In the pediatric population, use is established but may be subject to age and weight restrictions for certain indications, requiring dose calculation based on body size.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Official regulatory documents define the interaction profile of Cicloviral (Aciclovir) primarily through competition for the body’s elimination pathways and the potential for additive effects on organ systems. All interaction statements are derived from official government-issued labels.

Pharmacokinetic Interactions (Increased Exposure)

Cicloviral is eliminated mainly by active renal tubular secretion. Co-administration with other medicines that share this process, such as probenecid or cimetidine, reduces Cicloviral’s renal clearance and consequently increases its plasma concentration (AUC). Similarly, co-administration with mycophenolate mofetil results in increased plasma exposure for both substances due to competition for renal tubular clearance.

Pharmacodynamic and Substance Interactions

An additive risk of renal impairment is officially documented when Cicloviral is used concomitantly with any other medicinal products classified as nephrotoxic. Aciclovir may also significantly increase the serum levels of theophylline (up to 50% increase in AUC), requiring careful consideration.

Population-Specific Notes

The interaction profile is officially noted to be more pronounced in geriatric patients and individuals with renal impairment. Reduced kidney function in these populations leads to higher Cicloviral plasma concentrations, increasing the risk of exposure-related effects. The official labels state that food has no effect on the absorption of Aciclovir, allowing administration with or without meals.

Mechanism of Action

Selective Bioactivation by Viral Enzymes

The mechanism of Aciclovir is initiated by pathogen-specific bioactivation, requiring chemical modification by the virus-encoded Viral Thymidine Kinase (TK). This initial phosphorylation determines selectivity, allowing the drug to be activated and predominantly trapped inside cells expressing the viral enzyme. This activation process minimizes interference with the host's uninfected cellular processes, establishing targeted activity.


Arresting Replication via DNA Chain Termination

Once fully phosphorylated to its triphosphate form, the drug acts as a nucleoside analogue that directly targets the Viral DNA Polymerase, the enzyme responsible for creating the virus's genetic material. By binding to and competitively inhibiting this enzyme, and critically, by being incorporated into the new viral DNA strand, the drug causes an obligate chain termination. This molecular event arrests the creation of new viral particles, which establishes the physiological consequence of reduced viral proliferation.


Mechanism Constraints: Dependence on Viral State

The drug's mechanism is inherently limited by the state of the virus. It is only functionally effective when the virus is in its lytic (actively replicating) phase, as the necessary activating enzyme is being produced. The mechanism is functionally irrelevant during the latent (dormant) phase and is rendered ineffective against viral strains that have developed resistance through mutations that impair the Viral Thymidine Kinase.

Dosage and Administration Information

How Cicloviral is Used: Official Administration Guidelines

Cicloviral (Aciclovir) is prescribed based strictly on fixed, published dosing schedules and is administered via three primary routes. Treatment must generally be initiated as early as possible upon the first sign of symptoms, such as during the prodromal period, for optimal use.


Administration Routes and Scheduling

Route Forms and Frequencies (Adult)
Oral 200 mg, 400 mg, or 800 mg tablets/capsules; typically 5 times daily for acute treatment (omitting night dose) or 2 to 4 times daily for long-term suppression.
Intravenous (IV) Infusion for severe or systemic infections, typically dosed at 5 mg/kg or 10 mg/kg body weight every 8 hours.
Topical Cream or Ophthalmic Ointment, typically applied 5 times daily to the affected area.

Procedural and Population Adjustments

Dosing Duration: Acute oral treatment courses typically last 5 to 10 days. Suppressive therapy may be continued for up to 12 months, followed by re-evaluation.

Special Conditions: Oral forms may be taken with or without food, but adequate fluid intake is recommended for all oral use. IV administration must be given by slow infusion over a one-hour period to ensure proper delivery.

Dose Adjustment: Dosage must be reduced in patients with renal impairment (poor kidney function) based on the measured creatinine clearance. Older adults may also require dose reduction due to likely age-related changes in kidney function. If a dose is missed, it is generally recommended to take it as soon as remembered, unless it is almost time for the next scheduled dose, in which case the missed dose is skipped to prevent doubling the dose.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Cicloviral

The research base for Cicloviral (Aciclovir) contributes to the broader evidence landscape for antiviral medicines. This overview describes the structure of the available scientific literature, including Randomized Controlled Trials (RCTs) and Systematic Reviews, focusing strictly on what the studies explored and which populations were included, without offering clinical guidance or recommendations.

Evidence for Use in Acute Herpes Simplex Infections

This section summarizes the structure of short-term Randomized Controlled Trials (RCTs) that were observed in patients experiencing acute episodes, such as cold sores and genital herpes. Studies examined outcomes related to physical discomfort and outcomes describing episodic or acute changes in skin lesions. Research contributes to the broader evidence landscape for the established role of the medicine, which was observed in a high volume of these short-term studies.

Evidence for Use in Managing Herpes Recurrence

This part outlines the design of long-term clinical trials that research examined for patients experiencing frequently recurring outbreaks. Trials examined outcomes related to systemic or functional imbalance and changes in outcomes reflecting daily functioning or activity level. Findings describe patterns observed in the patterns of symptomatic episodes documented across the study periods.

Evidence for Use in Herpes Zoster and Severe Infections

This summary describes the nature of the research available for managing Herpes Zoster (Shingles) and critical conditions like Herpes Simplex Encephalitis. Studies monitored outcomes linked to inflammatory or irritative states (pain severity ratings) and outcomes monitoring physiological strain or stress.

Long-Term Studies and Uncertainty

Research exploring the durations of study observation includes trials with follow-up periods that were limited to the course of the acute infection, as well as dedicated studies tracking long-term protocols explored in research. Separately, long-term effects are not fully established beyond the defined trial periods. For children younger than 2 years of age, regulatory scientific bodies often note that appropriate studies have not been performed; data for certain groups remain insufficient. Research describes group patterns, not personal outcomes.

Key Studies & References

  1. Topical and Systemic Therapeutic Approaches in the Treatment of Oral Herpes Simplex Virus Infection: A Systematic Review
  2. Long-Term Use of Anti-viral Drugs for Recurrent Herpes - Clinical Guidelines

Frequently Asked Questions (FAQ)

Common questions about Cicloviral (FAQ)


Q: How quickly does Cicloviral usually start working?

A: Official guidelines emphasize the importance of starting treatment as early as possible, ideally at the first sign of symptoms (the prodromal phase). Early initiation is considered important for the medicine to effectively inhibit the virus’s replication cycle, which official guidance describes as contributing to optimal use. This is described in official documents as vital to the drug's therapeutic action.


Q: Is Cicloviral available without a prescription in some places?

A: Oral and intravenous forms of the medicine are generally classified as prescription-only medicines by most regulatory bodies. However, certain low-strength, topical formulations (creams) intended for cold sores may be available for purchase without a prescription in some jurisdictions. Official classifications depend on the route of administration and local laws.


Q: What should be done if someone accidentally takes too much Cicloviral?

A: Official labeling advises that patients who have taken an overdose should be closely observed for any signs of toxicity. Regulatory documents note that a severe overdose, particularly with the intravenous form, may lead to crystallization of the drug in the kidneys. Regulatory documents indicate that medical attention may be sought if an overdose is suspected.


Q: Does Cicloviral interact with common pain relievers like ibuprofen?

A: The medicine is eliminated from the body mainly through the kidneys. Regulatory warnings advise that Cicloviral should be used with caution if taken with any other medicine that is classified as nephrotoxic (having the potential to be harmful to the kidneys). Individuals who are concerned about potential interactions may review all current medicines with a healthcare provider.


Q: Is there a generic version of Cicloviral available?

A: Yes, the active ingredient in Cicloviral is Aciclovir (Acyclovir), which is a substance that has been used for decades. This compound is a foundational treatment recognized globally and is available under various generic and brand names, which is typical for established medicines.


Q: Does taking Cicloviral affect birth control pills?

A: Official patient information sheets state that Cicloviral is not known to interfere with the effectiveness of hormonal birth control, such as contraceptive pills. The available regulatory data does not indicate a need for additional contraceptive methods while using this medicine.


Q: Is Cicloviral considered a high-risk medication?

A: Official labeling contains Warnings regarding potential serious effects that have been documented, such as severe neurological issues and acute renal failure (a sudden kidney problem). These risks are noted particularly in older adults or individuals with existing kidney impairment, emphasizing the need for monitoring.


Q: Does Cicloviral contain any gluten or common allergens?

A: The official list of inactive ingredients, known as excipients (such as fillers or binders), is available on the regulatory labeling for each specific dosage form. Individuals with concerns about specific allergens may refer to the complete ingredient list (excipients) for the prescribed form.


Q: Why is it important to use Cicloviral exactly as directed?

A: The way the medicine works requires that it be started as early as possible and taken at set, scheduled times to maintain effective concentration levels in the body. This continuous presence is necessary for the drug to interrupt the virus's replication cycle effectively.


Q: Can people who have liver problems take Cicloviral?

A: Official documentation for the medicine primarily focuses on the importance of renal (kidney) function because the drug is eliminated mostly by the kidneys. While Cicloviral is minimally processed by the liver, specialized regulatory information suggests it should be used with caution in cases of severe hepatic (liver) impairment.


Q: Is there any research about Cicloviral being used for other conditions?

A: Official indications (licensed uses) only cover various herpes virus infections. However, in the scientific community, research has explored the drug’s potential for other purposes, such as its effects in patients co-infected with HIV-1, as documented in clinical trial reports.


Q: Why do official documents emphasize keeping track of side effects while on Cicloviral?

A: Monitoring is critical because certain serious side effects, especially those related to the kidneys and nervous system, have been documented to occur. Official documents state that these adverse events are often reversible if the medicine is discontinued or the dosage is adjusted promptly.


Q: Can Cicloviral be crushed or split if it is a tablet?

A: Regulatory instructions regarding the physical alteration of the tablet can vary depending on the specific product formulation. Some official guides mention that the tablet may be dispersed in a small amount of water. Patients should follow the specific directions for use provided with their exact dosage form.


Q: What happens when Cicloviral is stopped?

A: For patients using the medicine for long-term suppression, regulatory documents indicate that treatment should be stopped after a certain period, often 6 to 12 months. This stopping period is followed by a re-evaluation to see if the pattern of viral recurrence has changed.


Q: Do official patient information leaflets mention anything about driving while on Cicloviral?

A: Yes, official labeling states that side effects like dizziness, drowsiness, or certain neurological symptoms may impair a patient’s ability to safely drive or operate machinery. Patients are advised to ensure they are not experiencing these effects before engaging in such activities.


Q: How does Cicloviral affect the immune system?

A: The drug’s mechanism is highly selective; its primary function is to directly target and inhibit the viral DNA polymerase (the virus's replication mechanism). This specific action on the virus itself is noted to minimize disruption to the processes of the host’s healthy, uninfected cells.


Q: Are there any warnings about combining Cicloviral with alcohol?

A: Official patient resources, based on regulatory data, suggest that while alcohol is generally not considered an absolute contraindication, combining it with Cicloviral may worsen certain common side effects. These potentially worsened effects include headache, nausea, and dizziness.


Q: Can a person take Cicloviral if they are already taking aspirin?

A: Official interaction guidance generally finds no direct interaction between Cicloviral and aspirin. However, all official interactions advise caution with medicines that may affect the kidneys. A comprehensive review of all concurrent medications may be conducted with a healthcare professional.


Q: Does the packaging for Cicloviral include a patient information leaflet?

A: Yes, regulatory requirements in most countries mandate that all prescription medicines, including Cicloviral, must be supplied with a Patient Information Leaflet (PIL). This leaflet contains essential official safety and use information.


Q: Is an allergic reaction to Cicloviral common?

A: Official safety data indicates that severe allergic reactions, such as anaphylaxis, are Rare or Very Rare. However, mild skin reactions like rashes and pruritus (itching) are officially listed as Common side effects that have been reported.


Q: What's the difference between the active and inactive ingredients in Cicloviral?

A: The active ingredient is Aciclovir, which is the chemical substance responsible for producing the desired antiviral therapeutic effect. The inactive ingredients (excipients) are other necessary substances, such as fillers, coloring agents, or binders, that form the final product but do not have a medicinal effect.


Q: Are there any common foods or drinks to avoid when using Cicloviral?

A: Official regulatory labels state that food has no effect on the absorption of the medicine, meaning it can be taken with or without meals. However, caution is advised with drinks like alcohol as they may increase the severity of certain common side effects, such as dizziness.


Q: Do studies show Cicloviral is effective for its main use?

A: The research evidence base for Cicloviral (Aciclovir) is substantial and includes many Randomized Controlled Trials (RCTs) supporting its purpose. Official documents describe that the body of evidence contributes to the established role of the medicine for its licensed uses.


Q: Can older adults use Cicloviral safely?

A: Official guidelines define the use of Cicloviral in geriatric patients as Conditional Use. This is because there is an increased potential for neurological side effects and reduced renal function (kidney problems) is common in older adults, requiring careful evaluation and possible dose adjustment.


Q: What does the term 'contraindication' mean in relation to Cicloviral?

A: A contraindication is a term used in official documentation to describe a specific condition or situation in which the medicine should not be used because it could be harmful. For Cicloviral, the key contraindication is a known history of hypersensitivity (allergic reaction) to the drug or a related medicine like Valaciclovir.


Q: Does Cicloviral work the same way for everyone who takes it?

A: The medicine's mechanism requires the virus to be actively replicating to function effectively. Regulatory sources describe that the drug is functionally ineffective when the virus is in its latent (dormant) phase or if the viral strain has developed resistance. Therefore, its level of activity can vary based on the state of the infection.


Q: If someone is allergic to [Name of different drug], can they still take Cicloviral?

A: The medicine is strictly contraindicated if a patient is allergic to its active ingredient, Aciclovir, or to the related drug Valaciclovir. For allergies to other, unrelated medications, the regulatory guidance does not specify contraindication, but an allergy history review is typically necessary to determine individual eligibility.

How should Cicloviral be stored and disposed of?

How to Store and Dispose of Cicloviral (Aciclovir)

Cicloviral must be stored under specific conditions to maintain its effectiveness. Oral forms require storage at controlled room temperature, maintaining 15 C to 25 C (59 F to 77 F). The medicine must be protected from light and moisture and kept in its tightly closed container.

Child Safety and Stability

Regulatory labeling dictates that this medicine must be kept out of the sight and reach of children. Do not use Cicloviral after the expiry date (EXP) printed on the packaging.

Official Disposal Rules

Official disposal instructions prohibit discarding unused or expired Cicloviral via wastewater or household trash. Patients must ask a pharmacist for the correct method to dispose of the medicine, following pharmaceutical waste procedures to protect the environment.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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