Valtrexvalacyclovir
According to the FDA label: VALTREX is a deoxynucleoside analogue DNA polymerase inhibitor indicated for: Adult Patients ( 1.1 ) Cold Sores (Herpes Labialis) Genital Herpes Treatment in immunocompetent patients (initial or recurrent episode) Suppression in immunocompetent or HIV-1−infected patients Reduction of transmission Herpes Zoster Pediatric Patients ( 1.2 ) Cold Sores (Herpes Labialis) Chickenpox Limitations of Use ( 1.3 ) The efficacy and safety of VALTREX have not been established in immunocompromised patients…
44,612 adverse event reports submitted to the FDA (2003–2026)
Top Reported Adverse Events
The most frequently reported events in association with Valtrex in the FAERS database. These are events reported by patients taking this medication, not necessarily caused by it. A single report may include multiple events.
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Drug Ineffective 2,733 reports
A report that the medication did not work as expected for the person taking it. This is a reporting category, not a sign the drug is defective. It simply means someone felt it was not helping their condition.
Full definition in the glossary →Nausea 2,687 reports
The feeling of sickness in your stomach that often comes before vomiting.
Full definition in the glossary → See all drugs reporting this event →Fatigue 2,590 reports
Extreme tiredness or lack of energy that does not improve with rest.
Full definition in the glossary → See all drugs reporting this event →Off Label Use 2,357 reports
Using a medication for a condition or in a way that the FDA has not officially approved. This is common and often legal, and a report of it does not mean something went wrong. Doctors sometimes prescribe drugs off label based on their judgment.
Full definition in the glossary →Diarrhoea 2,176 reports
Loose or watery bowel movements, often frequent. Also spelled diarrhea in American English.
Full definition in the glossary → See all drugs reporting this event →Pyrexia 1,991 reports
The medical term for fever, meaning a raised body temperature.
Full definition in the glossary → See all drugs reporting this event →Headache 1,989 reports
Pain in the head or upper neck.
Full definition in the glossary → See all drugs reporting this event →Pain 1,786 reports
A general report of physical discomfort, used when no more specific location is given.
Full definition in the glossary →Dizziness 1,579 reports
A feeling of being lightheaded, unsteady, or like the room is spinning.
Full definition in the glossary → See all drugs reporting this event →Vomiting 1,527 reports
Throwing up the contents of the stomach.
Full definition in the glossary → See all drugs reporting this event →Pneumonia 1,473 reports
An infection that inflames the air sacs in the lungs, which can cause cough, fever, and difficulty breathing.
Full definition in the glossary →Rash 1,427 reports
An area of irritated, red, or bumpy skin.
Full definition in the glossary → See all drugs reporting this event →Dyspnoea 1,392 reports
Shortness of breath or difficulty breathing. Also spelled dyspnea in American English.
Full definition in the glossary → See all drugs reporting this event →Asthenia 1,305 reports
Physical weakness or lack of strength.
Full definition in the glossary →Acute Kidney Injury 1,156 reports
A sudden drop in how well the kidneys are working. It is often temporary and can have many causes.
Full definition in the glossary →
Ranked by frequency of reports, not severity. The most-reported event is not necessarily the most dangerous or the most common in patients taking this drug.
Who Is Reporting
Demographics of patients in FAERS reports that included this information. Not all reports include patient demographics.
By Sex
View reporter sex data as a table
| Sex | Reports |
|---|---|
| Female | 24,528 |
| Male | 15,903 |
| Unknown | 81 |
By Age Group
View age group data as a table
| Age group | Reports |
|---|---|
| 0-17 | 613 |
| 18-34 | 2,599 |
| 35-49 | 4,802 |
| 50-64 | 8,822 |
| 65-74 | 7,365 |
| 75+ | 5,721 |
This shows who filed reports, reflecting who takes this drug and who tends to report, not who is at greatest risk.
Reported Outcomes
Outcomes recorded in FAERS reports that included Valtrex. A single report may involve multiple reactions, each with a different outcome. These categories are defined by FDA reporting guidelines, not by PillSignal.
View outcome data as a table
| Outcome | Reports |
|---|---|
| Other Serious | 19,963 |
| Hospitalization | 17,742 |
| Non-Serious | 12,459 |
| Death | 3,595 |
| Life-Threatening | 2,290 |
| Disability | 992 |
Serious outcomes are far more likely to be reported than mild ones, so this overstates how often outcomes are serious. A recorded death does not mean the drug caused it.
Report Volume Over Time
Number of FAERS reports received per quarter for Valtrex. Changes in volume may reflect shifts in prescribing rates, media attention, or reporting behavior, not changes in the medication's safety profile.
View report trend as a table
| Year | Reports |
|---|---|
| 2003 | 2 |
| 2004 | 709 |
| 2005 | 799 |
| 2006 | 898 |
| 2007 | 1,057 |
| 2008 | 1,191 |
| 2009 | 1,149 |
| 2010 | 1,173 |
| 2011 | 1,241 |
| 2012 | 1,501 |
| 2013 | 1,127 |
| 2014 | 1,205 |
| 2015 | 1,892 |
| 2016 | 2,107 |
| 2017 | 1,691 |
| 2018 | 1,879 |
| 2019 | 2,192 |
| 2020 | 2,357 |
| 2021 | 2,977 |
| 2022 | 4,616 |
| 2023 | 4,266 |
| 2024 | 4,131 |
| 2025 | 3,666 |
| 2026 (partial) | 786 |
The steep increase around 2004 reflects the FDA's move to electronic submission, not a change in this drug's safety. Trends track reporting volume, not risk.
Medications commonly reported with Valtrex
In FDA adverse event reports that mention Valtrex, these medications appeared most often in the same report.
- Sulfamethoxazole And Trimethoprim (6,477 reports)
- Dexamethasone (6,255 reports)
- Acetaminophen (6,011 reports)
- Lenalidomide (5,470 reports)
- Aspirin (4,965 reports)
This reflects co-occurrence in submitted reports, not evidence of drug interaction or combined risk. People often report several medications taken for the same condition or for unrelated reasons. Talk to a doctor or pharmacist about your specific medications.
Related Drugs
Other medications with similar adverse event profiles in FDA FAERS reports.
Data Source
This data is sourced from the FDA's Adverse Event Monitoring System (AEMS), formerly FAERS, via the OpenFDA API. PillSignal is not affiliated with the FDA.
View this data on the FDA website →Data last updated: June 2026