Valacyclovir

Valtrex treats cold sores, initial/recurrent genital herpes, and shingles in immunocompetent adults. It also suppresses recurrent genital herpes in immunocompetent adults and adults with HIV-1 whose CD4 count is at least 100 cells/mm³. Reduction of genital-herpes transmission is a separate labeled use in immunocompetent adults, studied in discordant heterosexual couples; efficacy beyond 8 months, with multiple partners, or in non-heterosexual couples is unestablished. Suppression reduces outbreaks but does not eradicate HSV or eliminate transmission.

The label supports cold sores from age 12 and chickenpox in immunocompetent children age 2 to less than 18. It does not establish pediatric genital-herpes or shingles treatment, chickenpox treatment below 2 or at/above 18, cold-sore treatment below 12, or neonatal/infant HSV suppression. Apart from the defined HIV genital-herpes suppression population, labeled immunocompromised use is unestablished. Disseminated shingles and late-start treatment have separate evidence gaps.

The following regimens apply with creatinine clearance at least 50 mL/min. Take tablets with or without food. Begin cold-sore therapy at the earliest prodrome; efficacy after a papule, vesicle, or ulcer appears is unestablished. Begin genital-herpes therapy promptly; initial-episode benefit is greatest within 48 hours, with efficacy after 72 hours unestablished; recurrent-episode efficacy after 24 hours is unestablished. Start shingles promptly, preferably within 48 hours; efficacy after 72 hours is unestablished.

Age at least 12, cold sores: 2 g twice 12 hours apart for 1 day. Immunocompetent children age 2 to less than 18, chickenpox: 20 mg/kg per dose three times daily for 5 days, maximum 1 g per dose; begin within 24 hours of rash. Do not extrapolate these regimens to neonatal HSV or pediatric genital herpes/shingles. Data are unavailable for pediatric creatinine clearance below 50 mL/min/1.73 m².

Use adult creatinine clearance in mL/min and the correct indication row. These are doses/intervals; use the associated indication’s duration. The label does not supply a separate transmission-reduction renal row—do not invent one or assume every 500-mg regimen is equivalent. Renal function can change during dehydration or acute illness.

Give the renal-adjusted dose after hemodialysis on dialysis days. The label’s pharmacokinetic discussion does not call for supplemental doses after CAPD or continuous arteriovenous hemofiltration/dialysis; modern dialysis modalities still require individualized verification. A pharmacist may prepare 25 or 50 mg/mL suspension from 500-mg Valtrex tablets using the exact USP-NF vehicle/flavor procedure. This is not a factory-supplied liquid and should not be mixed at home. Confirm mg/mL, shake well, and use a calibrated oral device.

CDC recommends 1 g twice daily for 7–10 days for a first episode, extending if healing is incomplete; the label specifies 10 days. CDC also permits 1 g daily for 5 days for recurrent HSV-2, alongside the labeled 500-mg twice-daily 3-day regimen. For frequent recurrences (≥10/year), 500 mg daily suppression can be less effective. Discuss ongoing suppression annually; CDC documents longer-term experience despite the label’s trial-duration limits. CDC’s HIV episodic regimen is 1 g twice daily for 5–10 days, beyond the label’s defined HIV suppression indication. For recurrent genital herpes in pregnancy, CDC recommends 500 mg twice daily starting at 36 weeks; this requires obstetric management and does not guarantee prevention of neonatal infection. Severe/CNS/disseminated infection requires specialist assessment and often IV acyclovir, not extrapolated oral dosing.

Clinically significant hypersensitivity to valacyclovir, acyclovir, or any formulation component is contraindicated, including anaphylaxis or a severe cutaneous adverse reaction. Do not rechallenge after a valacyclovir/acyclovir-associated SCAR. Renal impairment requires dose adjustment; it is not itself listed as a formal contraindication.

The current selected Valtrex label has no boxed warning. Its TTP/HUS, renal, neurologic, hypersensitivity, and severe-skin-reaction warnings remain important.

Headache, nausea, and abdominal pain are commonly reported in adult trials; headache is prominent in adolescent cold-sore trials. Postmarketing reports include severe hypersensitivity, CNS disturbances, renal failure, hepatic abnormalities, blood disorders, and severe skin reactions; frequency cannot be estimated reliably. Excess dosing can precipitate acyclovir-related renal injury and neurotoxicity. Suspected overdose needs prompt clinical/poison-center assessment; acute renal failure with anuria may benefit from hemodialysis under medical care.

Review other potentially nephrotoxic medicines, hydration, and changing renal function because combined risk can increase acute kidney injury. The renal-dose algorithm and symptom assessment remain essential even though section 7 does not identify a routine clinically significant interaction.

Cimetidine/probenecid can increase acyclovir exposure by reducing renal clearance, but the label does not recommend a dose adjustment for these studied combinations in people with normal renal function. This does not establish safety of the same exposure in renal impairment. Food does not materially change acyclovir bioavailability, so tablets may be taken with or without meals. No invented CYP interaction or automatic dose change is supplied.

Human data over several decades have not identified a drug-associated increase in major birth defects, but miscarriage and other outcome data remain insufficient. Untreated maternal HSV also poses fetal/neonatal risk; coordinate treatment with obstetric care. Acyclovir, the metabolite, enters breast milk; infant effects and milk-production data are insufficient. Consider breastfeeding benefits and maternal clinical need rather than treating pregnancy or lactation as a contraindication. The separate CDC late-pregnancy regimen is identified in dosing.

Use only the established pediatric indication/age regimens unless a specialist separately reviews an off-label use. Pediatric renal-impairment data below CrCl 50 mL/min/1.73 m² are absent. Older adults more often need renal dose reduction and have greater renal/CNS adverse-event risk. The label’s immunocompromised evidence is limited to specified HIV genital-herpes suppression; transplant or advanced-HIV treatment should not be inferred from immunocompetent dosing.

Apply the adult renal table and dialysis timing; monitor clinical changes that can alter clearance. Cirrhosis pharmacokinetic studies showed slower conversion to acyclovir without a change in the extent of conversion or acyclovir half-life; the label does not recommend dose modification for cirrhosis. Hepatic disease does not negate a concurrent renal adjustment. No pediatric renal algorithm is established.

Valacyclovir is converted to acyclovir. Viral thymidine kinase initiates phosphorylation; the active triphosphate inhibits viral DNA polymerase and terminates DNA-chain elongation. Altered viral thymidine kinase or polymerase can confer resistance, with potential cross-resistance to related antivirals. Persistent or progressive lesions during appropriate treatment require reassessment rather than simply repeating the same regimen.

Oral valacyclovir is rapidly absorbed and nearly completely converted through first-pass intestinal/hepatic metabolism to acyclovir and L-valine. After a 1-g dose, acyclovir bioavailability is about 55% and is not materially altered by food. Acyclovir is cleared substantially through the kidneys; its half-life is about 2.5–3.3 hours with normal renal function and is prolonged in end-stage renal disease. Hemodialysis removes a meaningful fraction, explaining post-dialysis dosing.

Confirm the indication, symptom-onset timing, immune status, age, renal function, hydration, and concomitant kidney-risk medicines. Reassess creatinine/clearance when risk or clinical status warrants; follow urine output and mental status with suspected toxicity. Inspect severe rash/mucosal symptoms promptly. Assess response and adherence if lesions persist; immunocompromised, severe, atypical, or neurologic disease requires further evaluation. The label does not establish one fixed laboratory frequency for every short course.

Start the prescribed episodic course at the first symptoms and observe the one-day cold-sore limit. Maintain adequate hydration. For a missed dose, take it when remembered without doubling or exceeding the prescribed amount. Seek urgent care for severe rash/mucosal sores, allergy, confusion, seizures, or markedly reduced urine output. Valacyclovir is not a cure; avoid sexual contact when lesions or symptoms are present and use safer-sex practices because asymptomatic shedding persists. Suppression does not prevent every transmission or protect against other STIs.

Valtrex 500-mg tablets are blue, film coated and capsule shaped, printed “VALTREX 500 mg”; the 30-count source bottle is NDC 0173-0933-08. The 1-g tablets are blue/capsule shaped with partial scorebars on both sides and printed “VALTREX 1 gram”; the 30-count bottle is NDC 0173-0565-04. Generic appearances and repackaged NDCs vary; verify the dispensed product.

The selected product supplies oral tablets equivalent to 500 mg or 1 g valacyclovir (as its hydrochloride salt). The label defines pharmacy preparation of 25- or 50-mg/mL suspension from 500-mg tablets for patients needing a liquid. It does not supply an intravenous valacyclovir product or a universal substitute recipe for other tablets/vehicles.

Store Valtrex tablets at 15–25°C (59–77°F) in a well-closed container. For the exact label-defined suspension, use an amber glass bottle with child-resistant closure, refrigerate at 2–8°C, shake well, and discard after 28 days. Confirm pharmacy labeling if another preparation is dispensed; do not generalize this stability to a different vehicle or concentration.