Generic name
Fosphenytoin sodium: adverse event reports filed with FDA
664 reports list it as a suspect or interacting product, 2004–2026. Class: Anti-epileptic agent. Also reported as Fosphenytoin Sodium Injection Usp.
- 664
- reports as suspect product
- 0% of all reports · about 30 a year
- 20
- reports, 12 months to June 2026
- 33 in the 12 months before
- 86.9%
- marked serious by the reporter
- 78.1% across the class
- 14.8%
- record death among outcomes, as reported
- 98 reports · not verified by FDA
Between January 2004 and June 2026, 664 adverse event reports received by FDA list fosphenytoin sodium, a generic name as a suspect or interacting product. Reports that mention it only as a concomitant medication (197) are left out of every figure here.
In the 12 months to June 2026, 20 reports listed it, down 39% from 33 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 30 reports a year and 0% of the 20,646,523 reports in the database, and 0.2% of the reports for the anti-epileptic agent 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 (14.8%), off label use (5.7%) and cardiac arrest (4.7%). A report can list several reactions, so shares add to more than 100%; 209 different terms appear across these reports. Drug ineffective is recorded in 14.8% of these reports, a larger share than in the median anti-epileptic agent drug (11.3%).
86.9% of the reports are marked serious by the reporter (78.1% across the class); 14.8% record death among the outcomes and 34% record hospitalisation, as reported. 42% of the reports came from physicians, and the largest patient age group is 45 to 64 (17.9%). 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 Fosphenytoin sodium reports recording the termmedian drug in anti-epileptic agent
- Drug ineffectivethe medicine did not work as expected14.8%98
- Off label useused for a purpose or in a way not on the label5.7%38
- Cardiac arrestthe heart stopped4.7%31
- Blood pressure decreaseda low blood pressure reading3.3%22
- Hypotensionlow blood pressure3.3%22
- Toxicity to various agentspoisoning or toxic effect of one or more substances3.3%22
- Respiratory depressionslow or shallow breathing2.7%18
- Seizurea fit or convulsion2.4%16
- Drug interactionan interaction between medicines2%13
- Pyrexiafever2%13
- Respiratory failurethe lungs could not supply enough oxygen1.8%12
- Bradycardiaslow heart rate1.7%11
- Cardiogenic shockshock from the heart failing to pump1.7%11
- Drug eruption1.7%11
- Erythemaskin redness1.7%11
- Product use issuea problem in how the product was used1.7%11
- Rhabdomyolysismuscle breakdown1.7%11
- Accidental overdosean accidental overdose1.5%10
- Anticonvulsant drug level below therapeutic1.5%10
- Infusion site extravasationinfusion fluid leaked into surrounding tissue1.5%10
- Overdosea dose above the recommended amount1.5%10
- Rashskin rash1.5%10
- Respiratory symptom1.5%10
- Status epilepticus1.5%10
- Alanine aminotransferase increasedraised liver enzyme (ALT)1.4%9
- Anticonvulsant drug level increased1.4%9
- Medication errora mistake in prescribing, dispensing or taking a medicine1.4%9
Top 30 of 209 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 23 drugs in the anti-epileptic agent 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 269,757 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. 38% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Status epilepticus | 161 | 24.2% |
| Epilepsy | 64 | 9.6% |
| Seizure | 63 | 9.5% |
| Convulsion | 33 | 5% |
| Convulsion prophylaxis | 19 | 2.9% |
| Partial seizures | 10 | 1.5% |
The indication field is filled in by the reporter and is often blank; shares are of all 664 reports.
In context
| Measure | Fosphenytoin sodium | Anti-epileptic agent | All reports |
|---|---|---|---|
| Reports as suspect product | 664 | 269,757 | 20,646,523 |
| Share of that pool | — | 0.2% | 0% |
| Reports, latest 12 months | 20 | — | 1,332,454 |
| Marked serious | 86.9% | 78.1% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 148 | 126 | 91 |
| Hospitalisation recorded, per 1,000 reports | 340 | 314 | 213 |
| Consumer-filed share | 2.6% | 30.1% | 45.8% |
| Top term, share of reports | Drug ineffective 14.8% | median 11.3% | 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 anti-epileptic agent class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Gabapentin | generic | 74,316 | 4,447 | 68.7% |
| Lamotrigine | generic | 44,520 | 2,806 | 88% |
| Lamictal | brand | 32,368 | 996 | 65.4% |
| Valproic acid | generic | 21,177 | 1,031 | 96.7% |
| Depakote | brand | 14,219 | 297 | 65.4% |
| Phenytoin | generic | 12,618 | 464 | 92.9% |
| Valproate sodium | generic | 11,588 | 708 | 97.5% |
| Sabril | brand | 10,909 | 139 | 63.5% |
| Oxcarbazepine | generic | 8,078 | 715 | 87.7% |
| Dilantin | brand | 8,011 | 78 | 71.7% |
| Trileptal | brand | 7,664 | 157 | 85.7% |
| Zonisamide | generic | 4,885 | 363 | 87.3% |
| Divalproex sodium | generic | 4,071 | 399 | 82.4% |
| Vigabatrin | generic | 3,664 | 263 | 80.6% |
| Phenytoin sodium | generic | 2,974 | 68 | 84.4% |
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 Fosphenytoin sodium reports
How many adverse event reports has FDA received for Fosphenytoin sodium?
664 reports list Fosphenytoin sodium as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 20 of them arrived in the latest 12 months. Another 197 list it only as a concomitant medication.
What reactions are recorded in Fosphenytoin sodium reports?
drug ineffective (14.8%), off label use (5.7%), cardiac arrest (4.7%), blood pressure decreased (3.3%) and hypotension (3.3%). 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 Fosphenytoin sodium was responsible.
How serious are the reports?
86.9% are marked serious by the reporter. Among the outcomes recorded, 14.8% of reports include death and 34% 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?
physician (42%), other health professional (28%) and pharmacist (22%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Fosphenytoin sodium rising?
20 reports in the 12 months to June 2026, down 39% from 33 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 Fosphenytoin sodium 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 Fosphenytoin sodium?
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 Fosphenytoin sodium as a suspect or interacting product; reports listing it only as a concomitant medication (197) 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.