Acyclovir Antiviral Tablets for Herpes Treatment

What Acyclovir Is and How It Works

Acyclovir is an oral antiviral medicine used for herpes simplex virus (HSV‑1 and HSV‑2), varicella (chickenpox), and herpes zoster (shingles). It helps reduce viral replication and shortens symptom duration. CanadianInsulin is a prescription referral service. Prescriptions are verified with your clinic, and orders are filled by licensed Canadian pharmacies. We partner only with vetted pharmacies to source authentic medications across a broad selection at value‑focused pricing.

Acyclovir is a guanosine nucleoside analogue. Viral thymidine kinase activates it inside infected cells. The active triphosphate then inhibits viral DNA polymerase and causes chain termination. Selective activation in infected cells limits impact on human DNA polymerases. Oral tablets are common for outpatient care, with strengths such as 200 mg, 400 mg, and 800 mg. Acyclovir can be used episodically during outbreaks or as suppressive therapy to reduce recurrences and viral shedding.

Indications include first‑episode and recurrent genital herpes, herpes labialis (cold sores), shingles, and chickenpox in appropriate patients. Dosing and duration vary by condition and clinical factors such as timing of initiation, renal function, and immune status.

Dosage and Usage

• First‑episode genital herpes (adults): 200 mg five times daily for 10 days, or 400 mg three times daily for 7–10 days.
• Recurrent genital herpes (episodic): 200 mg five times daily for 5 days, or 400 mg three times daily for 5 days; start at first signs or prodrome.
• Suppressive therapy for frequent recurrences: 400 mg twice daily (dose and duration individualized by the prescriber).
• Herpes labialis (cold sores): regimens include 200 mg five times daily for 5 days, or 400 mg three times daily for 5 days.
• Herpes zoster (shingles): 800 mg five times daily for 7–10 days; benefit is greater when started within 72 hours of rash onset.
• Varicella (adults): commonly 800 mg four times daily for 5 days; start early in illness when indicated.
• Administration: tablets may be taken with or without food. Adequate hydration helps lower the risk of renal side effects.
• Renal impairment: dose adjustments are often required; the prescriber sets the regimen.
• Missed dose: a dose may be taken when remembered unless it is near the next scheduled dose; do not double doses.

• Storage: keep tablets at 20–25°C (68–77°F); brief excursions 15–30°C (59–86°F) are acceptable.
• Protect from moisture. Keep in the original, tightly closed container with the label intact.
• Do not use past the expiration date. Keep out of reach of children and pets.
• Travel: pack in carry‑on luggage. Keep your prescription and labeled container accessible for screening.
• Avoid extreme heat (car glove compartments, hot trunks). Use a small pill organizer for short trips.
• Set phone reminders while traveling to stay on schedule.

Benefits and Savings

Acyclovir helps shorten outbreak duration, reduce pain, and speed lesion healing when started promptly. Suppressive therapy lowers recurrence frequency and can reduce viral shedding, which may reduce transmission risk when combined with safer‑sex practices. It has decades of clinical use, with well‑understood efficacy and safety when dosed appropriately.

Tablets offer convenient oral dosing across several strengths, which supports individualized regimens. Many customers save 60–80% vs U.S. prices.

Side Effects and Safety

• Common: nausea, vomiting, diarrhea, abdominal pain, headache, dizziness, fatigue, rash, and pruritus.
• Less common: elevation of liver enzymes, photosensitivity, and changes in taste.
• Renal effects: crystalluria or acute kidney injury can occur, especially with dehydration or pre‑existing renal impairment.
• Neurologic effects (usually with high levels or renal dysfunction): agitation, confusion, tremor, hallucinations, or somnolence.
• Drug interactions: agents that affect renal tubular secretion (e.g., probenecid, cimetidine) or other nephrotoxins can increase levels or renal risk.

Serious reactions are uncommon but include hypersensitivity reactions, severe renal dysfunction, or neurotoxicity. Risk rises with renal impairment, advanced age, dehydration, or very high doses. Report concerning symptoms such as severe confusion, significant decrease in urine output, or signs of an allergic reaction.

Onset Time

For recurrent HSV, symptom relief often begins within 24–72 hours, especially when therapy starts at prodrome or first lesion. Lesions typically crust and heal within 5–10 days. In first‑episode genital herpes, improvement may take a few days, with healing over 2–3 weeks.

For shingles, pain reduction often begins within several days, with crusting by 7–10 days. Early initiation (within 72 hours of rash) provides the greatest benefit and can reduce the risk of complications such as postherpetic neuralgia. For chickenpox, fever and new lesion formation may lessen within 24–48 hours when started early in the illness.

Compare With Alternatives

Valacyclovir is a prodrug of acyclovir with higher oral bioavailability. It often allows less frequent dosing (for example, twice daily for episodic therapy or once to twice daily for suppression). Indications overlap, including genital herpes, cold sores, and shingles. Some patients prefer its simplified schedules; others prefer the lower per‑tablet cost of acyclovir.

Famciclovir, a prodrug of penciclovir, is another oral alternative for HSV and shingles. It offers different single‑day or short‑course options for episodic therapy in certain cases and is commonly dosed two to three times daily depending on the indication.

Topical antiviral options (such as acyclovir cream for cold sores) may help when started early but are generally adjunctive and less systemic than oral therapy.

Combination Therapy

• Suppressive antiviral therapy plus barrier methods can reduce genital herpes transmission risk.
• Pain management for shingles may include acetaminophen or NSAIDs; neuropathic pain agents may be used for postherpetic neuralgia under prescriber guidance.
• Topical anesthetics (e.g., lidocaine) may be used for localized pain relief in cold sores or shingles lesions.
• Hydration and avoidance of unnecessary nephrotoxic drugs help lower renal risk during therapy.
• In immunocompromised care plans (e.g., HIV or transplant settings), acyclovir may be part of broader protocols individualized by specialists.

Patient Suitability and Cost‑Saving Tips

Acyclovir may be appropriate for adults with first‑episode or recurrent genital herpes, frequent herpes labialis, shingles, or adult varicella when indicated. Clinical timing matters; earlier initiation generally improves outcomes for episodic therapy. Renal function, age, immune status, and concomitant medicines guide dosing and monitoring.

It may be unsuitable or require caution in severe renal impairment, dehydration, or when interacting nephrotoxic drugs are required. Use during pregnancy or breastfeeding should be directed by the prescriber, who weighs maternal benefits and fetal or infant risks. Acyclovir is not effective for non‑herpetic conditions such as canker sores caused by aphthous ulcers, bacterial infections, or fungal infections.

Cost‑saving ideas include choosing generic acyclovir, comparing tablet strengths to match prescribed total daily dose, and considering multi‑month quantities when appropriate. Ordering refills ahead of time can help avoid urgent local purchases at higher prices.

Authoritative Sources

FDA Prescribing Information for Acyclovir Tablets

Health Canada Drug Product Database: Acyclovir

DailyMed: Acyclovir Tablets, USP

Order Acyclovir from CanadianInsulin: add to cart, upload your prescription, and we ship with prompt, express, cold‑chain handling.

This page is educational and does not replace advice from your healthcare professional. Always follow your prescriber’s directions and the medication guide that comes with your prescription.