💊 Valacyclovir (Valacyclovir Hydrochloride)
Valacyclovir is an oral antiviral medicine used to treat certain herpes virus infections, including cold sores, genital herpes, shingles (herpes zoster), and chickenpox in children. Your doctor or pharmacist determines the dose and duration appropriate for your condition.
In Arabic: فالاسيكلوفير
🏷️ Brand names & manufacturers
Packages shown are US-market (DailyMed). Brands available in Palestine are in the price section below.
Valacyclovir Hydrochloride🏭 Redpharm Drug
Valacyclovir🏭 Sportpharm LLC
Valacyclovir🏭 SUN PHARMACEUTICAL INDUSTRIES, INC.
Valacyclovir🏭 Direct _Rx✅ What it is used for
- Treatment of cold sores (herpes labialis) in adults and children aged 12 years and older
- Treatment of the initial and recurrent episodes of genital herpes in immunocompetent adults
- Chronic suppressive therapy of recurrent genital herpes in immunocompetent and HIV-1–infected adults
- Reduction of transmission of genital herpes in immunocompetent adults
- Treatment of herpes zoster (shingles) in adults
- Treatment of chickenpox in children aged 2 to less than 18 years
🧪 Active ingredient
The active ingredient is valacyclovir (as the hydrochloride salt). It is rapidly converted in the body to acyclovir, which blocks replication of viral DNA and is active against herpes simplex virus types 1 and 2 and varicella-zoster virus.
🌿 Benefits
- Helps reduce symptoms of herpes infection when treatment is started early
- Helps prevent recurrent genital herpes episodes when used as suppressive therapy
- Helps reduce transmission of genital herpes to a partner
📝 How to use
- Tablets may be taken with or without meals.
- The dose and duration are set by your doctor or pharmacist for your condition; do not change the dose on your own.
- Treatment is best started at the earliest symptom (such as tingling, itching, or burning for cold sores), as directed by your doctor.
- For shingles, treatment is most effective when started within 48 hours of the onset of rash.
- For recurrent genital herpes, treatment should start at the first sign or symptom of an episode.
💊 Dosage forms
- Tablets 500 mg (unscored)
- Tablets 1 gram (partial break line)
⚠️ Common side effects
- Headache
- Nausea
- Abdominal pain
- Dizziness (reported in cold sore trials)
🚨 Serious — seek medical help
- Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS)
- Acute renal failure
- Central nervous system effects such as agitation, hallucinations, confusion, and encephalopathy
- Severe cutaneous adverse reactions (including Stevens-Johnson syndrome and toxic epidermal necrolysis); stop the drug immediately and seek care if a painful rash with mucosal involvement or a progressive severe rash develops
- Serious hypersensitivity reactions such as anaphylaxis
⛔ Do not use if
- Clinically significant hypersensitivity (e.g., anaphylaxis or severe cutaneous adverse reactions) to valacyclovir, acyclovir, or any component of the formulation
❗ Warnings & precautions
- Elderly patients, those with underlying kidney disease, those taking other nephrotoxic drugs, or inadequately hydrated patients are at higher risk of acute renal failure; use with caution and reduce the dose in renal impairment.
- Neurological effects (agitation, hallucinations, confusion) may occur, especially in elderly patients or when the dose is higher than appropriate for kidney function.
- Efficacy and safety have not been established in immunocompromised patients, except for suppression of genital herpes in HIV-1–infected patients.
- Efficacy has not been established when treatment of an initial genital herpes episode is started more than 72 hours after symptom onset, or of a recurrent episode more than 24 hours after onset.
- Efficacy of treatment started after clinical signs of a cold sore (papule, vesicle, or ulcer) have developed has not been established.
- Tell your doctor right away if you develop a severe rash, neurological symptoms, or reduced urine output.
🔄 Drug interactions
- No clinically significant drug-drug or drug-food interactions are known according to the label.
- However, taking other nephrotoxic drugs at the same time increases the risk of acute renal failure; tell your doctor or pharmacist about everything you take.
🤰 Pregnancy
Decades of clinical data in pregnant women have not identified a drug-associated risk of major birth defects, but data are insufficient regarding miscarriage or adverse maternal or fetal outcomes. Untreated herpes simplex during pregnancy also carries risks to the fetus. Consult your doctor before use.
🍼 Breastfeeding
The label text provided contains no information on breastfeeding; consult your doctor or pharmacist.
🧒 Children
Used for cold sores in children aged 12 years and older and for chickenpox in children aged 2 to less than 18 years. Efficacy and safety have not been established in children under 12 years for cold sores, under 18 years for genital herpes and herpes zoster, or under 2 years for chickenpox. The dose is determined by the doctor.
👴 Older adults
Elderly patients are more likely to have reduced renal function and may need dose reduction, and are more likely to have renal or CNS adverse events. In a herpes zoster trial, pain after healing (post-herpetic neuralgia) lasted longer in patients 65 and older.
🌡️ Storage
Store at 20° to 25°C (68° to 77°F).
⏰ Missed dose
The label text provided does not include instructions for a missed dose; ask your doctor or pharmacist.
🆘 Overdose
Care should be taken to prevent inadvertent overdose. Acyclovir may precipitate in the renal tubules when its solubility is exceeded. In acute renal failure and anuria, hemodialysis may help until renal function is restored. Seek medical help immediately if overdose is suspected.
💰 Price & brands in your area
Local prices are currently available for Palestine; more countries are coming. Ask your pharmacist for local price and alternatives.
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Mechanism of action
Valacyclovir is the L-valyl ester of acyclovir, rapidly and nearly completely converted to acyclovir and L-valine by first-pass intestinal and/or hepatic metabolism. Acyclovir is phosphorylated intracellularly by viral thymidine kinase to the monophosphate, then to the diphosphate and triphosphate by cellular enzymes. Acyclovir triphosphate inhibits viral DNA replication in three ways: competitive inhibition of viral DNA polymerase, incorporation and chain termination, and inactivation of the polymerase. Absolute bioavailability of acyclovir is 54.5% ± 9.1% and is not altered by food.
Labeled dosing
General adult dosing per the label (to be set for the individual patient by the doctor or pharmacist): cold sores 2 g every 12 hours for 1 day; initial genital herpes 1 g twice daily for 10 days; recurrent genital herpes 500 mg twice daily for 3 days; suppression in immunocompetent patients 1 g once daily (alternative 500 mg once daily if 9 or fewer recurrences/year); HIV-1–infected patients (CD4+ ≥ 100 cells/mm³) 500 mg twice daily; reduction of transmission 500 mg once daily for the source partner; herpes zoster 1 g three times daily for 7 days. Dose reduction is required in renal impairment.
- An oral suspension (25 or 50 mg/mL) may be prepared extemporaneously from 500-mg tablets for pediatric patients who cannot use a solid dosage form.
- Pediatric dosing: cold sores (≥12 years) 2 g every 12 hours for 1 day; chickenpox (2 to <18 years) 20 mg/kg three times daily for 5 days, not to exceed 1 g three times daily.
- Efficacy for suppression has not been established beyond 1 year in immunocompetent patients and beyond 6 months in HIV-1–infected patients, nor for transmission reduction beyond 8 months in discordant couples.
- Monitor for TTP/HUS (seen at doses of 8 g/day in advanced HIV-1 disease and in bone marrow and renal transplant recipients) and discontinue if clinical and laboratory findings consistent with it occur.
- Discontinue immediately if a severe cutaneous adverse reaction (AGEP, DRESS, TEN, SJS) is suspected.
🎓 Key points for students
- Valacyclovir is a prodrug of acyclovir, rapidly converted after absorption.
- Activation depends on initial phosphorylation by viral thymidine kinase, which explains selectivity for infected cells.
- Antiviral activity is greater against HSV than VZV because of more efficient phosphorylation.
- Key serious adverse effects: TTP/HUS, acute renal failure, CNS effects, and severe cutaneous reactions.
- Elderly patients and those with renal impairment require caution and dose adjustment.
- Absorption is not affected by food.
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Can valacyclovir be taken with food?
Yes, it can be taken with or without meals.
When should I start treatment for cold sores?
It is best started at the first symptom, such as tingling, itching, or burning, as directed by your doctor.
Does valacyclovir cure herpes permanently?
The label does not state that it cures the infection permanently; it is used to treat episodes, to suppress recurrences, and to reduce transmission of genital herpes.
What are the most common side effects?
Headache, nausea, and abdominal pain.
Is it safe for older adults?
Older adults may need a lower dose because they are more likely to have reduced kidney function and are more prone to kidney and nervous system side effects, so use it with caution under medical supervision.
Can it be used during pregnancy?
Available data have not identified a risk of major birth defects, but data are insufficient in other respects; consult your doctor before use.
⚕️ For education only — not a substitute for advice from your doctor or pharmacist. Do not start or stop any medicine without advice. Source: official FDA drug label via openFDA (2026-05), simplified. Updated: 2026-11-10.