Drugs › Herpes simplex virus nucleoside analog DNA polymerase inhibitor
Brand name · Valacyclovir hydrochloride
Valtrex: adverse event reports filed with FDA
7,793 reports list it as a suspect or interacting product, 2004–2026. Class: Herpes simplex virus nucleoside analog DNA polymerase inhibitor.
- 7,793
- reports as suspect product
- 0% of all reports · about 348 a year
- 154
- reports, 12 months to June 2026
- 112 in the 12 months before
- 55.1%
- marked serious by the reporter
- 78.9% across the class
- 2%
- record death among outcomes, as reported
- 158 reports · not verified by FDA
Between February 2004 and June 2026, 7,793 adverse event reports received by FDA list the brand name Valtrex (valacyclovir hydrochloride) as a suspect or interacting product. Reports that mention it only as a concomitant medication (21,475) are left out of every figure here.
In the 12 months to June 2026, 154 reports listed it, up 38% from 112 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 348 reports a year and 0% of the 20,646,523 reports in the database, and 26.1% of the reports for the herpes simplex virus nucleoside analog DNA polymerase inhibitor class. How many people take it is not in the data, so a count is not a rate of occurrence.
Reporters most often recorded drug ineffective (13.7%), nausea (7.3%) and altered state of consciousness (7.2%). A report can list several reactions, so shares add to more than 100%; 994 different terms appear across these reports. Drug ineffective is recorded in 13.7% of these reports, about the same share as in the median herpes simplex virus nucleoside analog DNA polymerase inhibitor drug (12.5%).
55.1% of the reports are marked serious by the reporter (78.9% across the class); 2% record death among the outcomes and 30.9% record hospitalisation, as reported. 60.5% of the reports came from consumers, and the largest patient age group is 45 to 64 (18.5%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."
Reports by month, five years
Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
By year received
2026 covers reports received through June 2026 only.
Reactions recorded in the reports
share of Valtrex reports recording the termmedian drug in herpes simplex virus nucleoside analog dna polymerase inhibitor
- Drug ineffectivethe medicine did not work as expected13.7%1,071
- Nauseafeeling sick7.3%571
- Dizzinesslight-headedness or unsteadiness6.4%499
- Headachehead pain5.9%457
- Renal failure acute5.1%399
- Vomitingbeing sick4.9%380
- Dysarthria4.4%342
- Malaisegeneral feeling of being unwell4.1%321
- Rashskin rash4.1%320
- Pyrexiafever4.1%317
- Blood creatinine increasedraised creatinine, a kidney test3.7%287
- Toxic encephalopathy3.6%279
- Renal impairmentreduced kidney function3.5%272
- Painpain, site not specified3.4%263
- Decreased appetitereduced appetite3%235
- Diarrhoealoose or frequent stools3%231
- Herpes zostershingles2.9%228
- Encephalopathy2.9%225
- Hallucinationseeing or hearing things that are not there2.9%225
- Overdosea dose above the recommended amount2.9%225
- Fatiguetiredness2.9%224
- Acute kidney injurysudden loss of kidney function2.8%220
- Dyspnoeashortness of breath2.8%220
- Gait disturbancedifficulty walking2.7%214
- Confusional stateconfusion2.5%194
- Pruritusitching2.4%189
- Somnolencedrowsiness2.4%188
Top 30 of 994 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 5 drugs in the herpes simplex virus nucleoside analog dna polymerase inhibitor class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Outcomes recorded
Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 29,855 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."
Patients and reporters
Patient age
Patient sex
Who reported
Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 51.5% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Herpes zoster | 2,286 | 29.3% |
| Genital herpes | 706 | 9.1% |
| Herpes virus infection | 284 | 3.6% |
| Herpes simplex | 232 | 3% |
| Oral herpes | 147 | 1.9% |
| Prophylaxis | 89 | 1.1% |
The indication field is filled in by the reporter and is often blank; shares are of all 7,793 reports.
Drugs most often listed in the same reports
| Drug (any role in the report) | Reports | Share of Valtrex reports |
|---|---|---|
| Aspirin | 246 | 3.2% |
| Norvasc | 218 | 2.8% |
| Prednisone | 159 | 2% |
| Acyclovir | 142 | 1.8% |
| Lasix | 138 | 1.8% |
| Lipitor | 133 | 1.7% |
| Furosemide | 122 | 1.6% |
| Lyrica | 120 | 1.5% |
| Allopurinol | 111 | 1.4% |
| Pantoprazole | 108 | 1.4% |
Other products listed in reports where Valtrex is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.
In context
| Measure | Valtrex | Herpes simplex virus nucleoside analog DNA polymerase inhibitor | All reports |
|---|---|---|---|
| Reports as suspect product | 7,793 | 29,855 | 20,646,523 |
| Share of that pool | — | 26.1% | 0% |
| Reports, latest 12 months | 154 | — | 1,332,454 |
| Marked serious | 55.1% | 78.9% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 20 | 88 | 91 |
| Hospitalisation recorded, per 1,000 reports | 309 | 398 | 213 |
| Consumer-filed share | 60.5% | 30.9% | 45.8% |
| Top term, share of reports | Drug ineffective 13.7% | median 12.5% | 6.3% |
Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Other drugs in the herpes simplex virus nucleoside analog dna polymerase inhibitor class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Acyclovir | generic | 11,095 | 950 | 91.2% |
| Valacyclovir hydrochloride | generic | 5,237 | 773 | 92.4% |
| Valacyclovir | generic | 3,307 | 312 | 72.5% |
| Zovirax | brand | 2,423 | 14 | 78.6% |
Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.
Questions about Valtrex reports
How many adverse event reports has FDA received for Valtrex?
7,793 reports list Valtrex as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 154 of them arrived in the latest 12 months. Another 21,475 list it only as a concomitant medication.
What reactions are recorded in Valtrex reports?
drug ineffective (13.7%), nausea (7.3%), altered state of consciousness (7.2%), dizziness (6.4%) and headache (5.9%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Valtrex was responsible.
How serious are the reports?
55.1% are marked serious by the reporter. Among the outcomes recorded, 2% of reports include death and 30.9% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.
Who files these reports?
consumer or non-health professional (60.5%), physician (23.5%) and pharmacist (8.4%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Valtrex rising?
154 reports in the 12 months to June 2026, up 38% from 112 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.
Do these reports show that Valtrex was responsible for these reactions?
No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.
Is this a list of the side effects of Valtrex?
No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.
How do I report an adverse event?
Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Valtrex as a suspect or interacting product; reports listing it only as a concomitant medication (21,475) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.
Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.