Drugs › Pyrophosphate analog DNA polymerase inhibitor
Brand name · Foscarnet sodium
Foscavir: adverse event reports filed with FDA
779 reports list it as a suspect or interacting product, 2004–2026. Class: Pyrophosphate analog DNA polymerase inhibitor.
- 779
- reports as suspect product
- 0% of all reports · about 35 a year
- 24
- reports, 12 months to June 2026
- 16 in the 12 months before
- 97.7%
- marked serious by the reporter
- 98% across the class
- 27%
- record death among outcomes, as reported
- 210 reports · not verified by FDA
779 adverse event reports received by FDA list the brand name Foscavir (foscarnet sodium) as a suspect or interacting product, from January 2004 to June 2026. A further 317 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, 24 reports listed it, up 50% from 16 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 35 reports a year and 0% of the 20,646,523 reports in the database, and 31% of the reports for the pyrophosphate 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 off label use (24.3%), renal impairment (7.4%) and hypokalaemia (5.6%). A report can list several reactions, so shares add to more than 100%; 282 different terms appear across these reports. Off label use is recorded in 24.3% of these reports, about the same share as in the median pyrophosphate analog DNA polymerase inhibitor drug (24.3%).
97.7% of the reports are marked serious by the reporter (98% across the class); 27% record death among the outcomes and 39.4% record hospitalisation, as reported. 41.6% of the reports came from physicians, and the largest patient age group is 45 to 64 (28.9%). 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 Foscavir reports recording the termmedian drug in pyrophosphate analog dna polymerase inhibitor
- Off label useused for a purpose or in a way not on the label24.3%189
- Renal impairmentreduced kidney function7.4%58
- Hypokalaemialow blood potassium5.6%44
- Renal failurekidney failure5.4%42
- Acute kidney injurysudden loss of kidney function5.1%40
- Drug resistance4.7%37
- Pancytopenialow counts of all blood cells4.6%36
- Cytomegalovirus viraemia4.4%34
- Blood creatinine increasedraised creatinine, a kidney test3.6%28
- Pathogen resistance3.6%28
- Hypocalcaemialow blood calcium3.5%27
- Renal failure acute3.1%24
- Condition aggravatedthe condition being treated got worse3%23
- Drug ineffectivethe medicine did not work as expected3%23
- Toxic epidermal necrolysisa severe skin reaction with peeling3%23
- Multi-organ failure2.8%22
- Multiple organ dysfunction syndromeseveral organs failing2.8%22
- Encephalitis cytomegalovirus2.7%21
- Hypomagnesaemialow blood magnesium2.6%20
- Pneumonia cytomegaloviral2.6%20
- Diarrhoealoose or frequent stools2.3%18
- Bone marrow failure2.2%17
- Nephropathy toxic2.2%17
- Vomitingbeing sick2.2%17
- Cardiac arrestthe heart stopped2.1%16
Top 30 of 282 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 3 drugs in the pyrophosphate 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 2,514 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. 14.1% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Cytomegalovirus infection | 217 | 27.9% |
| Cytomegalovirus chorioretinitis | 54 | 6.9% |
| Human herpesvirus 6 infection | 17 | 2.2% |
| Cytomegalovirus viraemia | 14 | 1.8% |
| Herpes simplex | 13 | 1.7% |
| Encephalitis cytomegalovirus | 12 | 1.5% |
The indication field is filled in by the reporter and is often blank; shares are of all 779 reports.
In context
| Measure | Foscavir | Pyrophosphate analog DNA polymerase inhibitor | All reports |
|---|---|---|---|
| Reports as suspect product | 779 | 2,514 | 20,646,523 |
| Share of that pool | — | 31% | 0% |
| Reports, latest 12 months | 24 | — | 1,332,454 |
| Marked serious | 97.7% | 98% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 270 | 302 | 91 |
| Hospitalisation recorded, per 1,000 reports | 394 | 324 | 213 |
| Consumer-filed share | 7.3% | 6.1% | 45.8% |
| Top term, share of reports | Off label use 24.3% | median 24.3% | 4.1% |
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 pyrophosphate analog dna polymerase inhibitor class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Foscarnet | brand | 1,087 | 91 | 98.7% |
| Foscarnet sodium | generic | 648 | 47 | 97.2% |
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 Foscavir reports
How many adverse event reports has FDA received for Foscavir?
779 reports list Foscavir as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 24 of them arrived in the latest 12 months. Another 317 list it only as a concomitant medication.
What reactions are recorded in Foscavir reports?
off label use (24.3%), renal impairment (7.4%), hypokalaemia (5.6%), renal failure (5.4%) and acute kidney injury (5.1%). 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 Foscavir was responsible.
How serious are the reports?
97.7% are marked serious by the reporter. Among the outcomes recorded, 27% of reports include death and 39.4% 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 (41.6%), other health professional (29.8%) and pharmacist (12.8%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Foscavir rising?
24 reports in the 12 months to June 2026, up 50% from 16 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 Foscavir 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 Foscavir?
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 Foscavir as a suspect or interacting product; reports listing it only as a concomitant medication (317) 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.