Valacyclovir adverse event reports that FDA received

Name: Reaction terms in FDA adverse event reports that name Valacyclovir
Creator: Reported Reactions
License: https://creativecommons.org/publicdomain/zero/1.0/

Name type: Generic name
Class: Herpes simplex virus nucleoside analog DNA polymerase inhibitor
Also reported as: Valacyclovir Tablets, Valacyclovir Tablets Usp, Valacyclovir /01269701/

What a report is

A report is not proof that the drug was the cause of the event.

FDA says:

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product.
Source: openFDA, Drug Adverse Event Overview, section "Responsible use of the data". The site read the page on 2 Oct 2026. The data have the reports that FDA received through 30 Jun 2026.

FDA also says:

There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event. The information in these reports has not been scientifically or otherwise verified as to a cause and effect relationship and cannot be used to estimate the incidence of these events.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.
Source: openFDA, Response of the drug event API (meta.disclaimer). The site read the page on 2 Oct 2026.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

Drug reports received through 30 Jun 2026. Device reports have a separate cutoff, 30 Sep 2026. Why a report count is not a rate.

Reports on file

From May 2006 to June 2026, FDA received 3,307 adverse event reports that name Valacyclovir. In these reports the drug is a suspect or interacting product.

In the same period, 22,571 further reports name it only as a concomitant medicine. The counts on this page do not include these reports.

FDA received 312 reports in the 12 months to June 2026 and 356 in the 12 months before. FDA releases FAERS data every quarter, so the newest months are not complete. They grow in later releases.

Of the 1,332,454 drug reports that FDA received in the 12 months to June 2026, 312 (under 0.1%) name Valacyclovir. Reports from consumers or other non-health professionals were 31% of the reports that name Valacyclovir and 45.8% of all drug reports.

The number of people who use the product is not in the data. A count is not a rate. A count of reports is not a count of events or of patients, because one event can have more than one report.

There are many instances of duplicative reports and some reports do not contain all the necessary information.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

Suspect product

FDA records each drug in a report as suspect, concomitant or interacting. This page counts the reports in which Valacyclovir is suspect or interacting. FDA says:

Any number of the drugs may be marked as suspect if thought to be responsible for one or more of the reactions, but that information is not validated.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

Data version

openFDA FAERS release of 29 Oct 2026. Reports received through 30 Jun 2026.

Since the last update

FDA says:

Many factors can influence whether or not an event will be reported, such as the time a product has been marketed and publicity about an event.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

The information in these reports cannot be used to estimate the incidence (occurrence rates) of the events reported.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

The latest update of the FDA data, recorded on 28 Oct 2026, changed no count of this page.

In April to June 2026, FDA received 74 reports that name Valacyclovir.
In January to March 2026, FDA received 79.
In April to June 2025, FDA received 58.

April to June 2026 is the latest closed quarter in the data. A closed quarter is a quarter for which the FDA files have most of the reports.

All updates Feed of updates (RSS)

Reaction lookup

These are the reaction terms that the reports record, with the number of reports for each term. Type a term or a plain word to find its count.

What this list leaves out

The table lists the 287 reaction terms that 5 or more reports record. A term with fewer than 5 reports is not in the table.

The site keeps reaction terms for 3,265 of the 3,307 reports (98.7%).

The reports of the other years are not in the counts.

So a count in the table can be lower than the count of FDA.

Find a reaction term

The table shows the first 50 of 287 terms.

Reaction terms in the reports that name Valacyclovir, most reports first
Reaction term (MedDRA) and plain meaning	Reports	Share of the 3,307 reports
Drug ineffectivethe medicine did not work as expected	453	13.7%
Neurotoxicity	200	6%
Acute kidney injurysudden loss of kidney function	158	4.8%
Confusional stateconfusion	125	3.8%
Nauseafeeling sick	124	3.7%
Headachehead pain	122	3.7%
Febrile neutropeniafever with low white blood cells	119	3.6%
Rashskin rash	117	3.5%
Condition aggravatedthe condition being treated got worse	115	3.5%
Off label useused for a purpose or in a way not on the label	103	3.1%
Product substitution issuea problem after switching products	101	3.1%
Diarrhoealoose or frequent stools	98	3%
Fatiguetiredness	94	2.8%
Dizzinesslight-headedness or unsteadiness	92	2.8%
Painpain, site not specified	87	2.6%
Herpes zostershingles	84	2.5%
Foetal exposure during pregnancythe unborn baby was exposed to the medicine	79	2.4%
Encephalopathy	76	2.3%
Vomitingbeing sick	67	2%
Pruritusitching	62	1.9%
Toxicity to various agentspoisoning or toxic effect of one or more substances	62	1.9%
Rash maculo-papulara rash of flat and raised spots	59	1.8%
Deaththe patient died; cause not stated by this term	57	1.7%
Pyrexiafever	56	1.7%
Hallucinationseeing or hearing things that are not there	55	1.7%
Exposure during pregnancythe medicine was taken during pregnancy	54	1.6%
Astheniaweakness or lack of energy	53	1.6%
Drug resistance	52	1.6%
Dyspnoeashortness of breath	49	1.5%
Overdosea dose above the recommended amount	48	1.5%
Arthralgiajoint pain	47	1.4%
Neutropenialow neutrophils, a type of white blood cell	47	1.4%
Drug reaction with eosinophilia and systemic symptomsDRESS, a severe reaction with rash, fever and organ involvement	46	1.4%
Dysarthria	46	1.4%
Hepatic cytolysis	46	1.4%
Back pain	41	1.2%
Disease recurrencethe disease came back	40	1.2%
Somnolencedrowsiness	40	1.2%
Drug interactionan interaction between medicines	39	1.2%
Malaisegeneral feeling of being unwell	39	1.2%
Drug hypersensitivityan allergic-type reaction (the term names a medicine)	37	1.1%
Feeling abnormalfeeling odd or not right	37	1.1%
Hallucination, visual	37	1.1%
Renal failurekidney failure	37	1.1%
Completed suicidedeath by suicide	36	1.1%
Product use in unapproved indicationused for a purpose not on the label	35	1.1%
Hypersensitivityan allergic-type reaction	34	1%
Insomniadifficulty sleeping	34	1%
Gait disturbancedifficulty walking	33	1%
Incorrect dose administeredthe wrong dose was given	33	1%

Download all 287 terms of Valacyclovir (CSV)

The counts add to more than 3,307 reports, because one report can record more than one term. FDA says:

No individual drug is connected to any individual reaction. When a report lists multiple drugs and multiple reactions, there is no way to conclude from the data therein that a given drug is responsible for a given reaction.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

The CSV file has the same rows and the same limits. Its last row is a note that says so.

MedDRA term

The person who codes a report selects the preferred term that agrees best with the description of the reporter. The words under a term are the plain meaning that this site gives.

Not the label

The FDA-approved label of a product lists its adverse reactions. See the official pages at the end of this page.

Same ingredient, other names

Reporters write a brand name or a generic name. Each name has its own page and its own count.

Names of Valacyclovir with a page, in the order generic names, brand names, names as reported
Name	Name type	Reports
Valacyclovir (this page)	Generic name	3,307
Valacyclovir hydrochloride	Generic name	5,237
Valtrex	Brand name	7,793

Sum of the separately reported names: 16,337. A report that names two of these names is in the sum two times. The sum is not the number of reports for the ingredient.

FDA says:

Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

Importantly, the AEMS data by themselves are not an indicator of the safety profile of the drug or biologic.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

Outcomes by year

The table gives the outcomes that the reporters gave, in the terms of FDA.

Outcomes in the reports that name Valacyclovir, by the year of the openFDA file that holds the report

The table continues to the right.

Year of the openFDA file	Reports	Serious	Death	Life-threatening	Hospitalization (initial or prolonged)	Disability or Permanent Damage	Congenital Anomaly/Birth Defect	Other Serious (Important Medical Events)	Not serious
2004	0	0	0	0	0	0	0	0	0
2006	12	9	2	2	6	0	0	1	3
2007	31	25	1	0	6	1	8	10	6
2008	25	22	1	1	13	0	1	9	3
2009	17	13	1	0	7	0	0	6	4
2010	69	32	2	1	13	2	0	18	37
2011	86	50	1	3	24	4	0	27	36
2012	39	33	5	2	16	1	7	14	6
2013	92	55	11	4	18	1	0	36	37
2014	126	86	47	5	18	0	1	29	40
2015	120	52	2	4	29	2	0	41	68
2016	149	81	5	3	38	4	2	55	68
2017	171	98	25	5	40	2	0	64	73
2018	220	140	20	8	55	7	8	104	80
2019	222	148	12	9	56	6	1	99	74
2020	181	107	8	1	47	7	1	78	74
2021	258	196	12	8	94	7	2	144	62
2022	310	254	10	10	116	5	14	182	56
2023	278	231	9	12	103	2	8	169	47
2024	416	365	23	22	149	11	5	283	51
2025	306	249	18	6	120	5	0	174	57
2026	179	152	8	10	88	1	1	103	27

An outcome in a report is not proof that the drug was the cause. The reporter gives the outcome, and FDA does not verify it. FDA says:

The information in these reports has not been scientifically or otherwise verified as to a cause and effect relationship and cannot be used to estimate the incidence of these events.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

The six headings with the names of FDA are the outcome terms of FDA. A report can have more than one outcome. The columns Serious and Not serious are the two values of the openFDA field serious. For the value serious, openFDA gives this description:

The adverse event resulted in death, a life threatening condition, hospitalization, disability, congenital anomaly, or other serious condition
Source: openFDA, Drug adverse event fields (YAML reference). The site read the page on 2 Oct 2026.

The year is the year of the openFDA file that holds the latest version of the report. It is not always the year in which FDA first received the report. The chart of the next section uses the year of first receipt. The latest year is not complete.

Reports by year and month

Reports that name Valacyclovir, by the year in which FDA received them

The column of 2026 has an outline, because the year is not complete. It has the reports that FDA received through June 2026 only.

Show the figures of the chart as a table

Reports that name Valacyclovir, by the year in which FDA received them
Year	Reports
2006	10
2007	27
2008	29
2009	14
2010	48
2011	90
2012	67
2013	95
2014	130
2015	125
2016	150
2017	177
2018	222
2019	228
2020	193
2021	250
2022	292
2023	295
2024	430
2025	282
2026	153

Reports that name Valacyclovir, by month, five years to June 2026

FDA releases FAERS data every quarter, so the newest months are not complete. They grow in later releases.

Why a count moves

A count moves for many reasons. The guide gives FDA's words about them.

Patients and reporters

Age of the patient in the reports that name Valacyclovir
Age	Reports	Share
Under 2	10	0.3%
2 to 11	17	0.5%
12 to 17	26	0.8%
18 to 44	473	14.3%
45 to 64	696	21%
65 to 74	545	16.5%
75 and over	437	13.2%
Age not given	1,103	33.4%

Sex of the patient in the reports that name Valacyclovir
Sex	Reports	Share
Female	1,724	52.1%
Male	1,034	31.3%
Unknown or not given	549	16.6%

Type of reporter in the reports that name Valacyclovir
Reporter	Reports	Share
Physician	899	27.2%
Pharmacist	324	9.8%
Other health professional	954	28.8%
Lawyer	1	under 0.1%
Consumer or non-health professional	1,026	31%
Not given	103	3.1%

Age and sex are as the report gives them. The reporter is the primary source in the report. 55.5% of the reports give the United States as the country.

Reason for use

Reason for use (indication) that the reports of Valacyclovir record
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 reporter fills in the indication, and the field is often empty. Each share is of all 3,307 reports.

Drugs in the same reports

Other drugs that the reports of Valacyclovir name, in any role, in order of name
Drug	Reports that name the two
Acetaminophen	127
Acyclovir	275
Amlodipine	125
Bactrim	216
Dexamethasone	137
Fluconazole	106
Furosemide	96
Pantoprazole	130
Prednisone	193
Rituximab	95

The table has the 10 drug names that these reports name most. Two names in one report says only that the report recorded the two. It says nothing about the part of a product in the event.

FDA says:

Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

Importantly, the AEMS data by themselves are not an indicator of the safety profile of the drug or biologic.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

Pages near this one

Valacyclovir hydrochloride same ingredient
Valtrex same ingredient
Famciclovir same class
Acyclovir sodium same class
Acyclovir same class
Zovirax same class
Valaciclovir Hydrochloride next in the A to Z list
Valaciclovir next in the A to Z list
Valbenazine next in the A to Z list
Vagistat-1 next in the A to Z list
Valchlor next in the A to Z list
Vagifem Ld next in the A to Z list

These links are for navigation. No count selected them. The class page lists each drug of the class.

Official pages

DailyMed labels for ValacyclovirThe labels (prescribing information) that have this name, at the National Library of Medicine.
MedWatch Online Voluntary Reporting FormThe online form of FDA for a voluntary report.
MedWatch: The FDA Safety Information and Adverse Event Reporting ProgramThe page of the FDA program that receives reports about drugs and devices.
FDA Adverse Event Monitoring System (AEMS) Public DashboardThe public dashboard of FDA for adverse event reports on drugs and biologics.

The site checked these addresses on 2 Oct 2026. The links open in a new tab.

Cite this page

Reported Reactions. Valacyclovir: adverse event reports that FDA received. https://reportedreactions.com/drug/valacyclovir/ Source: U.S. Food and Drug Administration, openFDA Drug Adverse Event (FAERS) files, release of 29 Oct 2026. Reports received through 30 Jun 2026.

Where the data come from

The counts come from the openFDA Drug Adverse Event (FAERS) bulk files, release of 29 Oct 2026. The files have the reports that FDA received through 30 Jun 2026. A drug name is the name on the report. The site matches it to a brand name or a generic name of the National Drug Code Directory of 2 Nov 2026. A class is the pharmacologic class (EPC) of the FDA label.

A report is in the count when it names Valacyclovir as a suspect or interacting product. The 22,571 reports that name it only as a concomitant medicine are not in the count. The site does not publish a report narrative, a lot number, a detail of a patient or the identity of a reporter. The record of FDA is the authority. See how the site counts reports, the data sources and the corrections page.

Questions

Do these reports show that Valacyclovir was responsible for the reactions?

No. FDA says:

For any given report, there is no certainty that a suspected drug caused the event.
Source: FDA, FDA Adverse Event Monitoring System (AEMS) Public Dashboard. Content current as of 11 Mar 2026. The site read the page on 2 Oct 2026.

A reaction can relate to the condition that the drug treats, to other medicines, or to something else.

Is this the list of reactions on the label of Valacyclovir?

No. It is a count of what people reported to FDA: 3,307 reports from May 2006 to June 2026. The FDA-approved label of a product lists its adverse reactions. The official pages at the end of this page link to the labels.

Who sent these reports?

Consumer or non-health professional (31%), other health professional (28.8%) and physician (27.2%). These are the types of reporter for the reports that name this drug.

If a manufacturer receives an adverse event report, it is normally required to send the report to FDA.
Source: openFDA, Drug Adverse Event Overview. The site read the page on 2 Oct 2026.

How does a person report an adverse event?

FDA runs MedWatch, a program that takes voluntary reports from health professionals, patients and consumers. The guide on how to report has the links.

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