Pharmacologic class (EPC) · 3 drug pages

Influenza A M2 protein inhibitor: adverse event reports filed with FDA

4,578 reports list a drug in this class as a suspect or interacting product, 2004–2026.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event." The information in these reports "cannot be used to estimate the incidence of these events."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

4,578
reports across the class: 0% of all reports; 356
reports, 12 months to June 2026: 256 in the 12 months before; 67.8%
marked serious by the reporter: 57.4% across all reports; 3
drugs with a page: brand and generic names counted separately

Influenza A M2 protein inhibitor is a pharmacologic class (an FDA Established Pharmacologic Class) with 3 drug pages on this site. Together those drugs are listed as a suspect or interacting product in 4,578 adverse event reports received by FDA, 0% of the database, from June 2004 to June 2026.

356 reports arrived in the 12 months to June 2026, up 39% from 256 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. 67.8% of the class's reports are marked serious, 9.5% record death among the outcomes and 34% record hospitalisation, as reported.

Across the class the reactions recorded most often are hallucination (11.4%), fall (11.3%) and dyskinesia (9.9%). 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
Amantadine	generic	2,205	200	82%	Drug ineffective
GocovriAmantadine	brand	1,633	75	44%	Fall
Amantadine hydrochloride	generic	740	81	78.1%	Off label use

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

Hallucinationseeing or hearing things that are not there11.4%524
Falla fall11.3%519
Dyskinesiainvoluntary movements9.9%454
Drug ineffectivethe medicine did not work as expected9.2%421
Dizzinesslight-headedness or unsteadiness7.6%347
Tremorshaking7.1%324
Off label useused for a purpose or in a way not on the label6.8%313
Gait disturbancedifficulty walking6.4%294
Hallucination, visual6.1%277
Fatiguetiredness6%273
Constipationconstipation5.8%266
Confusional stateconfusion5.3%242
Balance disorderproblems with balance5.2%237
Insomniadifficulty sleeping5%229
Drug interactionan interaction between medicines4.9%224
Dry mouthdry mouth4.8%220
Somnolencedrowsiness4.8%219
Parkinson's disease4.2%190
Astheniaweakness or lack of energy3.7%170
Speech disordera speech problem3.5%162
Toxicity to various agentspoisoning or toxic effect of one or more substances3.5%159
Deaththe patient died; cause not stated by this term3.4%156
Nauseafeeling sick3.4%154
Anxietyanxiety3.3%152
Hypotensionlow blood pressure3.3%152

Solid bar: share of all class reports. Hollow bar: the median share across the 3 member drugs, the reference used on each member's page. One report can record several terms.

Outcomes, patients and reporters

Outcomes recorded

Death9.5%433

Life-threatening3.2%147

Hospitalisation (initial or prolonged)34%1,556

Disability1.5%69

Congenital anomaly0.2%8

Other serious43.4%1,987

Not serious32.2%1,473

Patient age

Under 20.1%6

2 to 110.7%31

12 to 171.3%61

18 to 447.2%331

45 to 6418.9%866

65 to 7422.8%1,043

75 and over17.1%782

Age not given31.8%1,458

Who reported

Physician19.3%885

Pharmacist6.5%297

Other health professional30.4%1,393

Lawyer0.1%3

Consumer or non-health professional40.3%1,846

Not given3.4%154

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 Influenza A M2 protein inhibitor reports

Which drugs are in the Influenza A M2 protein inhibitor class on this site?

Amantadine, Gocovri and Amantadine hydrochloride. Class membership comes from the pharmacologic class (EPC) on the drug's FDA label.

How many reports does the class have?

4,578 reports through June 2026, 356 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?

hallucination (11.4%), fall (11.3%), dyskinesia (9.9%), drug ineffective (9.2%) and dizziness (7.6%).

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.