Diphenhydramine
According to the FDA label: Diphenhydramine hydrochloride in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when diphenhydramine hydrochloride in the oral form is impractical.
79,187 adverse event reports submitted to the FDA (2003–2026)
Top Reported Adverse Events
The most frequently reported events in association with Diphenhydramine 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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Off Label Use 10,768 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 →Fatigue 7,785 reports
Extreme tiredness or lack of energy that does not improve with rest.
Full definition in the glossary → See all drugs reporting this event →Headache 7,459 reports
Pain in the head or upper neck.
Full definition in the glossary → See all drugs reporting this event →Nausea 6,605 reports
The feeling of sickness in your stomach that often comes before vomiting.
Full definition in the glossary → See all drugs reporting this event →Pain 6,496 reports
A general report of physical discomfort, used when no more specific location is given.
Full definition in the glossary →Drug Ineffective 6,364 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 →Infusion Related Reaction 5,619 reports
A reaction that happens during or shortly after a medication is given through an IV infusion.
Full definition in the glossary →Arthralgia 5,323 reports
Sinusitis 4,972 reports
Inflammation of the sinuses, the air-filled spaces around the nose, often causing congestion and pressure.
Full definition in the glossary →Dyspnoea 4,878 reports
Shortness of breath or difficulty breathing. Also spelled dyspnea in American English.
Full definition in the glossary → See all drugs reporting this event →Toxicity to Various Agents 4,854 reports
A broad reporting category used when the body has a harmful response, sometimes involving more than one substance.
Full definition in the glossary →Pneumonia 4,830 reports
An infection that inflames the air sacs in the lungs, which can cause cough, fever, and difficulty breathing.
Full definition in the glossary →Pyrexia 4,783 reports
The medical term for fever, meaning a raised body temperature.
Full definition in the glossary → See all drugs reporting this event →Nasopharyngitis 4,333 reports
The medical term for the common cold, an infection of the nose and throat.
Full definition in the glossary →Blood Pressure Increased 4,326 reports
A reading showing higher than normal blood pressure. Similar to hypertension, which describes the ongoing condition.
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 | 43,837 |
| Male | 23,156 |
| Unknown | 103 |
By Age Group
View age group data as a table
| Age group | Reports |
|---|---|
| 0-17 | 4,452 |
| 18-34 | 7,302 |
| 35-49 | 10,200 |
| 50-64 | 14,563 |
| 65-74 | 8,457 |
| 75+ | 4,590 |
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 Diphenhydramine. 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 | 41,901 |
| Hospitalization | 25,936 |
| Non-Serious | 17,366 |
| Death | 15,041 |
| Life-Threatening | 4,108 |
| Disability | 1,607 |
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 Diphenhydramine. 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 | 1 |
| 2004 | 106 |
| 2005 | 60 |
| 2006 | 180 |
| 2007 | 44 |
| 2008 | 115 |
| 2009 | 145 |
| 2010 | 673 |
| 2011 | 459 |
| 2012 | 667 |
| 2013 | 1,563 |
| 2014 | 2,642 |
| 2015 | 3,763 |
| 2016 | 6,158 |
| 2017 | 3,321 |
| 2018 | 4,161 |
| 2019 | 6,318 |
| 2020 | 11,889 |
| 2021 | 7,217 |
| 2022 | 7,620 |
| 2023 | 7,333 |
| 2024 | 6,333 |
| 2025 | 6,801 |
| 2026 (partial) | 1,618 |
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 Diphenhydramine
In FDA adverse event reports that mention Diphenhydramine, these medications appeared most often in the same report.
- Epinephrine (21,021 reports)
- Diphenhydramine Liquid Filled (20,673 reports)
- Methylprednisolone (16,215 reports)
- Prednisone (15,772 reports)
- Adrenalinum (14,907 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