Drugs › Herpes simplex virus nucleoside analog DNA polymerase inhibitor
Generic name
Valacyclovir: adverse event reports filed with FDA
3,307 reports list it as a suspect or interacting product, 2006–2026. Class: Herpes simplex virus nucleoside analog DNA polymerase inhibitor. Also reported as Valacyclovir Tablets, Valacyclovir Tablets Usp, Valacyclovir /01269701/.
- 3,307
- reports as suspect product
- 0% of all reports · about 164 a year
- 312
- reports, 12 months to June 2026
- 356 in the 12 months before
- 72.5%
- marked serious by the reporter
- 78.9% across the class
- 6.7%
- record death among outcomes, as reported
- 223 reports · not verified by FDA
3,307 adverse event reports received by FDA list valacyclovir, a generic name as a suspect or interacting product, from May 2006 to June 2026. A further 22,571 reports list it only as a concomitant medication, and those are not counted in the figures on this page.
In the 12 months to June 2026, 312 reports listed it, down 12% from 356 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 164 reports a year and 0% of the 20,646,523 reports in the database, and 11.1% 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.
The reactions recorded most often are drug ineffective (13.7%), neurotoxicity (6%) and acute kidney injury (4.8%). A report can list several reactions, so shares add to more than 100%; 689 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%).
72.5% of the reports are marked serious by the reporter (78.9% across the class); 6.7% record death among the outcomes and 31.9% record hospitalisation, as reported. 31% of the reports came from consumers, and the largest patient age group is 45 to 64 (21%). 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 Valacyclovir reports recording the termmedian drug in herpes simplex virus nucleoside analog dna polymerase inhibitor
- Drug ineffectivethe medicine did not work as expected13.7%453
- Neurotoxicity6%200
- Acute kidney injurysudden loss of kidney function4.8%158
- Confusional stateconfusion3.8%125
- Nauseafeeling sick3.7%124
- Headachehead pain3.7%122
- Febrile neutropeniafever with low white blood cells3.6%119
- Rashskin rash3.5%117
- Condition aggravatedthe condition being treated got worse3.5%115
- Off label useused for a purpose or in a way not on the label3.1%103
- Product substitution issuea problem after switching products3.1%101
- Diarrhoealoose or frequent stools3%98
- Fatiguetiredness2.8%94
- Dizzinesslight-headedness or unsteadiness2.8%92
- Painpain, site not specified2.6%87
- Herpes zostershingles2.5%84
- Foetal exposure during pregnancythe unborn baby was exposed to the medicine2.4%79
- Encephalopathy2.3%76
- Vomitingbeing sick2%67
- Pruritusitching1.9%62
- Toxicity to various agentspoisoning or toxic effect of one or more substances1.9%62
- Rash maculo-papulara rash of flat and raised spots1.8%59
- Deaththe patient died; cause not stated by this term1.7%57
- Pyrexiafever1.7%56
- Hallucinationseeing or hearing things that are not there1.7%55
- Exposure during pregnancythe medicine was taken during pregnancy1.6%54
- Astheniaweakness or lack of energy1.6%53
- Drug resistance1.6%52
- Dyspnoeashortness of breath1.5%49
- Overdosea dose above the recommended amount1.5%48
Top 30 of 689 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. 55.5% 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 | 544 | 16.4% |
| Antiviral prophylaxis | 177 | 5.4% |
| Prophylaxis | 163 | 4.9% |
| Herpes virus infection | 159 | 4.8% |
| Herpes simplex | 153 | 4.6% |
| Oral herpes | 118 | 3.6% |
The indication field is filled in by the reporter and is often blank; shares are of all 3,307 reports.
Drugs most often listed in the same reports
| Drug (any role in the report) | Reports | Share of Valacyclovir reports |
|---|---|---|
| Acyclovir | 275 | 8.3% |
| Bactrim | 216 | 6.5% |
| Prednisone | 193 | 5.8% |
| Dexamethasone | 137 | 4.1% |
| Pantoprazole | 130 | 3.9% |
| Acetaminophen | 127 | 3.8% |
| Amlodipine | 125 | 3.8% |
| Fluconazole | 106 | 3.2% |
| Furosemide | 96 | 2.9% |
| Rituximab | 95 | 2.9% |
Other products listed in reports where Valacyclovir 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 | Valacyclovir | Herpes simplex virus nucleoside analog DNA polymerase inhibitor | All reports |
|---|---|---|---|
| Reports as suspect product | 3,307 | 29,855 | 20,646,523 |
| Share of that pool | — | 11.1% | 0% |
| Reports, latest 12 months | 312 | — | 1,332,454 |
| Marked serious | 72.5% | 78.9% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 67 | 88 | 91 |
| Hospitalisation recorded, per 1,000 reports | 319 | 398 | 213 |
| Consumer-filed share | 31% | 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% |
| Valtrex | brand | 7,793 | 154 | 55.1% |
| Valacyclovir hydrochloride | generic | 5,237 | 773 | 92.4% |
| 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 Valacyclovir reports
How many adverse event reports has FDA received for Valacyclovir?
3,307 reports list Valacyclovir as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 312 of them arrived in the latest 12 months. Another 22,571 list it only as a concomitant medication.
What reactions are recorded in Valacyclovir reports?
drug ineffective (13.7%), neurotoxicity (6%), acute kidney injury (4.8%), confusional state (3.8%) and nausea (3.7%). 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 Valacyclovir was responsible.
How serious are the reports?
72.5% are marked serious by the reporter. Among the outcomes recorded, 6.7% of reports include death and 31.9% 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 (31%), other health professional (28.8%) and physician (27.2%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Valacyclovir rising?
312 reports in the 12 months to June 2026, down 12% from 356 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 Valacyclovir 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 Valacyclovir?
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 Valacyclovir as a suspect or interacting product; reports listing it only as a concomitant medication (22,571) 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.