Pharmacologic class (EPC) · 2 drug pages
Nucleoside analog antiviral: adverse event reports filed with FDA
59,646 reports list a drug in this class as a suspect or interacting product, 2004–2026.
- 59,646
- reports across the class
- 0.3% of all reports
- 630
- reports, 12 months to June 2026
- 728 in the 12 months before
- 67.2%
- marked serious by the reporter
- 57.4% across all reports
- 2
- drugs with a page
- brand and generic names counted separately
Nucleoside analog antiviral is a pharmacologic class (an FDA Established Pharmacologic Class) with 2 drug pages on this site. Together those drugs are listed as a suspect or interacting product in 59,646 adverse event reports received by FDA, 0.3% of the database, from January 2004 to June 2026.
630 reports arrived in the 12 months to June 2026, down 13% from 728 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. 67.2% of the class's reports are marked serious, 11.7% record death among the outcomes and 23.8% record hospitalisation, as reported.
Across the class the reactions recorded most often are fatigue (14.1%), anaemia (12.4%) and nausea (11.3%). The class median share shown beside each term is the middle value across the member drugs; it is the comparison used on every drug page in this class.
The members table is 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."
Drugs in the class
| Drug | Name type | Reports | Latest 12 months | Marked serious | Top term recorded |
|---|---|---|---|---|---|
| Ribavirin | generic | 49,384 | 83 | 64.9% | Fatigue |
| LonsurfTrifluridine and tipiracil | brand | 10,262 | 547 | 78.4% | Death |
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."
Reports by month, five years
FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
Reactions recorded across the class
share of class reports recording the termmedian drug in the class
- Fatiguetiredness14.1%8,433
- Anaemialow red blood cells12.4%7,376
- Nauseafeeling sick11.3%6,746
- Rashskin rash6.6%3,936
- Headachehead pain6.5%3,903
- Diarrhoealoose or frequent stools6.2%3,722
- Vomitingbeing sick6%3,570
- Deaththe patient died; cause not stated by this term5.9%3,530
- Pruritusitching5.8%3,486
- White blood cell count decreasedlow white cell count5.6%3,343
- Astheniaweakness or lack of energy5.5%3,296
- Decreased appetitereduced appetite5.5%3,291
- Pyrexiafever5.3%3,170
- Drug ineffectivethe medicine did not work as expected5.2%3,073
- Dyspnoeashortness of breath4.8%2,858
- Insomniadifficulty sleeping4.8%2,837
- Weight decreasedweight loss4.2%2,509
- Haemoglobin decreasedlow haemoglobin4%2,407
- Dizzinesslight-headedness or unsteadiness4%2,378
- Platelet count decreasedlow platelet count4%2,366
- Depressionlow mood3.7%2,180
- Hepatitis Chepatitis C infection3.5%2,068
- Painpain, site not specified3.4%2,034
- Malaisegeneral feeling of being unwell3.3%1,975
- Disease progressionthe disease advanced3.1%1,837
Solid bar: share of all class reports. Hollow bar: the median share across the 2 member drugs, the reference used on each member's page. One report can record several terms.
Outcomes, patients and reporters
Outcomes recorded
Patient age
Who reported
Grey bar: all 20,646,523 reports in the database. Outcome flags are as the reporter set them and are not verified by FDA.
Questions about Nucleoside analog antiviral reports
Which drugs are in the Nucleoside analog antiviral class on this site?
Ribavirin and Lonsurf. Class membership comes from the pharmacologic class (EPC) on the drug's FDA label.
How many reports does the class have?
59,646 reports through June 2026, 630 of them in the latest 12 months. A report listing two drugs of the class counts once for each.
What reactions are recorded most often?
fatigue (14.1%), anaemia (12.4%), nausea (11.3%), rash (6.6%) and headache (6.5%).
Can the members table be used to rank the drugs?
No. 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." Drugs differ in how many people take them, in the conditions they treat, in time on the market and in how diligently reports are collected.
How do I report an adverse event?
Through FDA MedWatch (Form FDA 3500, or 1-800-FDA-1088) or to the manufacturer. 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 class is the Established Pharmacologic Class most often attached to a drug's reports by openFDA's label harmonisation, or from the NDC Directory where reports carry none. 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.