OpenClaim

Interferon Side Effects

The most commonly reported side effects of interferon include multiple sclerosis relapse, influenza like illness, and fatigue, based on 215,342 FDA adverse event reports from 2004 to 2025. 2.3% of reports found the drug to be ineffective.

Interferon side effects

Percentages show how often each reaction appears relative to total reports for interferon.

1
Multiple Sclerosis Relapse5.0%10,790
2
Influenza Like Illness4.4%9,545
3
Fatigue3.8%8,275
4
Gait Disturbance3.0%6,548
5
Memory Impairment3.0%6,408
6
Fall2.9%6,243
7
Multiple Sclerosis Relapse2.8%6,096
8
Multiple Sclerosis2.8%5,956
9
Headache2.7%5,860
10
Pain2.6%5,634
11
Influenza Like Illness2.4%5,245
12
Fall2.4%5,179
13
Injection Site Pain2.4%5,076
14
Drug Ineffective2.3%4,874
15
Fatigue2.2%4,842

These are voluntary reports and do not establish that interferon caused these reactions.

Report severity

53.8%Serious115,862 reports
31.1%Hospitalizations67,025 reports
5.4%Fatal11,657 reports

Seriousness is determined by the reporter, not by OpenClaim.

Interferon drug interactions

Other drugs that appear in adverse event reports alongside interferon. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Natalizumab10.3%22,182
2
Dimethyl2.5%5,468
3
Dalfampridine2.5%5,457
4
Glatiramer-acetate0.5%988
5
Ribavirin0.4%909
6
Fingolimod0.4%806
7
Peginterferon0.3%713
8
Teriflunomide0.3%692
9
Ocrelizumab0.3%545
10
Methylprednisolone0.2%467
11
Gabapentin0.2%353
12
Baclofen0.2%329
13
Mitoxantrone-hydrochloride0.1%291
14
Ibuprofen0.1%280
15
Acetaminophen0.1%265

Taken alongside

1
Acetaminophen3.2%6,922
2
Baclofen3.1%6,710
3
Gabapentin2.9%6,139
4
Ergocalciferol2.8%6,105
5
Ibuprofen2.2%4,775
6
Levothyroxine-sodium1.8%3,974
7
Aspirin1.8%3,839
8
Lisinopril1.2%2,680
9
Omeprazole1.2%2,595
10
Atorvastatin-calcium1.1%2,370
11
Hydrochlorothiazide1.0%2,212
12
Clonazepam1.0%2,206
13
Metoprolol1.0%2,161
14
Amlodipine1.0%2,154
15
Calcium1.0%2,106

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports interferon side effects

77.0% of interferon adverse event reports involve female patients and 20.9% involve male patients. The largest age group is adult at 86%. These figures reflect who reports side effects, not underlying risk.

Sex

Female77.0%
Male20.9%
Unknown2.0%

Age group

< 20.6%
2–110.3%
12–170.6%
18–6486.4%
65+12.2%

What is interferon used for

Conditions and purposes for which patients were taking interferon when the adverse event was reported.

Abnormal Sensation In EyeAccidental ExposureAccidental Exposure To ProductAcral Lentiginous MelanomaAcute Disseminated EncephalomyelitisAcute LeukaemiaAcute Lung InjuryAcute Lymphocytic LeukaemiaAcute Myeloid LeukaemiaAcute Respiratory Distress SyndromeAdenocarcinoma PancreasAdjuvant TherapyAdult T-cell Lymphoma/leukaemiaAgranulocytosisAllergic Granulomatous Angiitis

Showing 15 of 733 indications

Interferon brand names and reporting trend

Interferon is sold under several brand names including Betaseron, Rebif, Intron A.

Brand names

Betaseron1,264
Rebif1,145
Intron A1,092
Actimmune409

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking interferon with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.