Prescription medication · Antiviral
valacyclovir
Also sold as Valtrex. Valacyclovir treats cold sores, genital herpes, and shingles.
Data updated 2026-05-15
- 39,048
- FDA reportsModerately reported
- 3
- InteractionsFew interactions
- 98% less
- Generic vs brandHuge savings
- $20.32
- Brand price (NADAC)
What the data shows
valacyclovir (Valtrex) is a prescription Antiviral, reported at a middle-of-the-pack volume (39,048 FDA reports), whose generic costs a fraction of the brand (about 98% less).
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
valacyclovir (Valtrex) is a prescription Antiviral. Valacyclovir treats cold sores, genital herpes, and shingles.
Valacyclovir is an antiviral medicine. It is used to treat infections caused by certain viruses.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Brand Price
$20.32/unit
Generic Price
$0.43/unit
Generic Savings
98%
Generic Available
Yes (7 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
NADAC price trail: VALACYCLOVIR HCL 1 GRAM TABLET
Same CMS presentation as the headline generic unit price above (3 effective dates). Adjacent % compares consecutive NADAC releases for this description only, not a patient out-of-pocket quote. Latest step: -2.4% vs prior release.
| Effective | NADAC / unit | vs prior | NDCs |
|---|---|---|---|
| January 17, 2024 | $0.5109/EA | - | 1 |
| April 17, 2024 | $0.4411/EA | -13.7% | 1 |
| December 18, 2024 | $0.4306/EA | -2.4% | 24 |
What it does
Valacyclovir treats cold sores, genital herpes, and shingles.
Common side effects
Headache, Nausea, Abdominal pain
Key warnings
Valacyclovir can cause serious problems like TTP/HUS, which is a blood disorder.
The sections below are summarized in plain English from valacyclovir's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Valacyclovir stops the virus from growing and spreading. It does this by blocking a key enzyme the virus needs to reproduce. This helps your body fight off the infection.
Side Effects (from patient reports)
Based on 39,048 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for valacyclovir, by number of reports
- Fatigue
Fatigue
2,294 reports
- Diarrhoea
Diarrhoea
2,120 reports
- Nausea
Nausea
1,838 reports
- Febrile Neutropenia
Febrile Neutropenia
1,545 reports
- Pyrexia
Pyrexia
1,490 reports
- Pneumonia
Pneumonia
1,448 reports
- Headache
Headache
1,355 reports
- Pain
Pain
1,301 reports
- Rash
Rash
1,241 reports
- Neutropenia
Neutropenia
1,150 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for valacyclovir each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where valacyclovir sits
valacyclovir has more FDA adverse-event reports than 69% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is valacyclovir; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 39,048 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
39,048
Reports Mentioning Death
3,520
9.0% of reports — not proof of cause
Hospitalization Reports
15,607
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | FATIGUE | 2,294 |
| 3 | DIARRHOEA | 2,120 |
| 5 | NAUSEA | 1,838 |
| 6 | FEBRILE NEUTROPENIA | 1,545 |
| 7 | PYREXIA | 1,490 |
| 8 | PNEUMONIA | 1,448 |
| 9 | HEADACHE | 1,355 |
| 10 | PAIN | 1,301 |
| 11 | RASH | 1,241 |
| 12 | NEUTROPENIA | 1,150 |
| 13 | ACUTE KIDNEY INJURY | 1,101 |
| 14 | DYSPNOEA | 1,063 |
| 15 | DEATH | 1,049 |
| 16 | ASTHENIA | 1,047 |
| 17 | COVID-19 | 1,001 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Valacyclovir can cause serious problems like TTP/HUS, which is a blood disorder. This is more likely in people with advanced HIV or who have had bone marrow or kidney transplants, especially if they take high doses (8 grams per day). It can also cause kidney failure, especially in older adults or people with kidney problems. Rarely, it can cause confusion, hallucinations, or agitation. Stop taking this medicine and contact your doctor immediately if you experience any of these side effects.
Known Drug Interactions
Some examples of drugs that are eliminated by active tubular secretion include, but are not limited to, acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs [see Warnings and Precautions (5.4) ] .
Mechanism: Both of these drugs are removed from the body through the same pathway in the kidneys, which may cause them to compete for exit.
Some examples include, but are not limited to, acyclovir, adefovir dipivoxil, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs [see Warnings and Precautions (5.3) ] .
Mechanism: Both of these drugs are removed from the body through the kidneys, and taking them together can increase the risk of kidney damage.
Some examples include, but are not limited to, acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs [see Warnings and Precautions ( 5.2)].
Mechanism: Both of these drugs are removed from the body by the kidneys, and taking them together can put extra stress on your kidney function.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
Common Questions
Can I take valacyclovir if I'm allergic to acyclovir?
How quickly does valacyclovir work?
Can valacyclovir cure herpes?
Does valacyclovir interact with other medications?
Can children take valacyclovir?
What should I do if I think I have a side effect?
Can I drink alcohol while taking valacyclovir?
How long can I take valacyclovir for suppressive therapy?
What if I have kidney problems?
Can valacyclovir prevent the spread of genital herpes?
What are the common side effects of valacyclovir?
Does valacyclovir interact with other medications?
What drug class is valacyclovir?
Is there a generic version of valacyclovir?
What pregnancy or breastfeeding source fields are listed for valacyclovir?
Related Medications in Antiviral
Other drugs grouped near valacyclovir - same-class peers and common alternatives.
acyclovir
Zovirax
Acyclovir is an antiviral medicine.
Compare with valacyclovir →
albendazole
Albenza
Albendazole is a medicine that fights parasites.
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amphotericin B
Ambisome, Fungizone
Amphotericin B liposome is an antifungal medicine.
Compare with valacyclovir →
anidulafungin
Eraxis
Eraxis is an antifungal medicine.
Compare with valacyclovir →
atovaquone/proguanil
Malarone
Malarone is a drug used to prevent and treat malaria.
Compare with valacyclovir →
Compare beyond drug class
Nationwide peers by FAERS volume & death-report share
Two PlainMeds-derived comparison paths for valacyclovir: nearest FDA FAERS report volume and nearest death-report share among drugs with at least 1,000 logged reports, excluding same-class neighbors listed above. Counts reflect reporting volume, not proven individual harm.
Similar FAERS report volume
Nearest drugs by total FAERS reports. This record: 39,048.
Similar death-report share
Nearest drugs by FAERS death-report share. This record: 9.01%.
- valproate Δ 0.00 pts · 19,772 reports · Anticonvulsant / Mood Stabilizer 9.01%death share
- risedronate Δ 0.05 pts · 30,089 reports · Bisphosphonate 8.96%death share
- levetiracetam Δ 0.06 pts · 127,698 reports · Anticonvulsant 9.07%death share
- ivermectin Δ 0.08 pts · 5,936 reports · Antiparasitic 9.10%death share
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
Save on valacyclovir
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What the FDA Data Shows for valacyclovir
The FDA label for valacyclovir (sold under brand names such as Valtrex) classifies it as a prescription-only medication in the Antiviral class. Valacyclovir treats cold sores, genital herpes, and shingles. Official labeling lists 3 commonly reported side effects, including Headache, Nausea, Abdominal pain.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 39,048 voluntary reports. The database also lists 3 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.43 versus $20.32 for the brand - a 98% generic savings.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.
Last updated: July 11, 2024
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages