What the label lists and what reports show
Cidofovir side effects
Cidofovir's FDA label: “The most frequently reported adverse events regardless of relationship to study drugs (cidofovir or probenecid) or severity are shown in Table 5.” FAERS holds 1,411 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is drug resistance (150 reports).
- Generic listed
- Boxed warning
Check it at the source: the cidofovir FDA label on DailyMed (effective October 25, 2023, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe most frequently reported adverse events regardless of relationship to study drugs (cidofovir or probenecid) or severity are shown in Table 5.
Table 5. All Clinical Adverse Events, Laboratory Abnormalities or Intercurrent Illnesses Regardless of Severity Occurring in >15% of Patients
| Reaction | * Patients receiving 5 mg/kg maintenance regimen in Studies 106 and 107. N = 115 * # patients (%) |
|---|---|
| Any Adverse Event | 115(100) |
| Proteinuria(≥30 mg/dL) | 101(88) |
| Nausea +/- Vomiting | 79(69) |
| Fever | 67(58) |
| Neutropenia(< 750 cells/mm 3 ) | 50(43) |
| Asthenia | 50(43) |
| Headache | 34(30) |
| Rash | 34(30) |
| Infection | 32(28) |
| Alopecia | 31(27) |
| Diarrhea | 30(26) |
| Pain | 29(25) |
| Creatinine Elevation (> 1.5 mg/dL) | 28(24) |
| Anemia | 28(24) |
| Anorexia | 26(23) |
| Dyspnea | 26(23) |
| Chills | 25(22) |
| Increased Cough | 22(19) |
| Oral Moniliasis | 21(18) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedNephrotoxicity: Renal toxicity, as manifested by ≥2+ proteinuria, serum creatinine elevations of ≥0.4 mg/dL, or decreased creatinine clearance ≤55 mL/min, occurred in 79 of 135 (59%) patients receiving cidofovir injection at a maintenance dose of 5 mg/kg every other week. Maintenance dose reductions from 5 mg/kg to 3 mg/kg due to proteinuria or serum creatinine elevations were made in 12 of 41 (29%) patients who had not received prior therapy for CMV retinitis (Study 106) and in 19 of 74 (26%) patients who had received prior therapy for CMV retinitis (Study 107). Prior foscarnet use has been associated with an increased risk of nephrotoxicity; therefore, such patients must be monitored closely (see CONTRAINDICATIONS , WARNINGS , DOSAGE AND ADMINISTRATION ). Neutropenia: In clinical trials, at the 5 mg/kg maintenance dose, a decrease in absolute neutrophil count to ≤500 cells/mm 3 occurred in 24% of patients. Granulocyte colony stimulating factor (GCSF) was used in 39% of patients. Decreased Intraocular Pressure/Ocular Hypotony: Among the subset of patients monitored for intraocular pressure changes, a ≥50% decrease from baseline intraocular pressure was reported in 17 of 70 (24%) patients at the 5 mg/kg maintenance dose. Severe hypotony (intraocular pressure of 0 to 1 mm Hg) has been reported in 3 patients. …
Source: FDA drug label, Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc., effective October 25, 2023 (SPL set 44966a7e-d777-40fb-956f-d0f31f737848), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,411 reports list cidofovir among the medicines taken, each a report of something that happened, not proof the medicine caused it; 394 are coded as a death and 513 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 21 reactions below, 4 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Cidofovir: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions