The table below shows the top 25 adverse events reported to the U.S. Food & Drug Administration (FDA) concerning finasteride used by younger men as a treatment for hair loss. The following filters were applied to minimize confounding factors: Date first received by FDA: 2018–2020 / Sex: Male / Age: 18-40 / Suspected product: Finasteride only / Reason for use: alopecia, androgenetic alopecia and other hair loss conditions only / Concomitant products: None.
The number after each adverse event indicates the number of times it was reported in this filtered data set.
| Adverse event category | % of top 25 adverse events |
| Sexual function Erectile Dysfunction – 398 Loss Of Libido / Libido Decreased – 366 Sexual Dysfunction – 100 | 31% |
| Neuropsychiatric domain Depression – 276 Anxiety – 199 Suicidal Ideation – 136 Feeling Abnormal – 123 Panic Attack – 80 | 29% |
| Sexual anatomy & physiology Testicular Pain – 96 Genital Hypoaesthesia [numbness] – 68 Penile Size Reduced – 59 Penis Disorder – 59 Ejaculation Disorder – 46 | 12% |
| Memory, cognition & attention Amnesia / Memory Impairment – 124 Cognitive Disorder – 90 Disturbance In Attention – 63 | 10% |
| Energy & musculoskeletal system Fatigue / Asthenia – 194 Muscle Atrophy – 68 | 9% |
| Sleep Insomnia – 142 | 5% |
| Sensory Tinnitus – 48 Vision Blurred – 44 | 3% |
| Endocrine Gynaecomastia – 43 | 2% |
See also: Adverse events affecting reproductive anatomy and sexual function and Firsthand reports submitted to FDA, acquired by FOIA request.
Explore and download adverse event data
Filtered data from FDA FAERS in Airtable (data can be downloaded). Filters:
- Initial FDA Received Date: 1 Jan 2018 – 31 Dec 2020
- Sex: Male
- Age: 18-40
- Reason for use: Alopecia conditions only (e.g. ‘Alopecia’, ‘Androgenetic alopecia’, ‘Diffuse alopecia’)
- Suspect product: Finasteride only
- Concomitant products: None
Comparison to adverse events of minoxidil
Minoxidil is another treatment for hair loss used by younger men. It has a similar patient population as finasteride, but a different mechanism. A comparison of adverse events (AEs) of each drug can shed light on whether AEs might be attributable to the population or the drug.
Data for both drugs were filtered using the same criteria: Date first received by FDA: 2018–2020 / Sex: Male / Age: 18-40 / Suspected product: Minoxidil only or Finasteride only / Reason for use: alopecia, androgenetic alopecia and other hair loss conditions / Concomitant products: None.
Minoxidil
| Adverse event group | % of top 25 AEs |
| Skin reactions | 40% |
| Incorrect use of product | 37% |
| Hair loss and drug ineffective | 19% |
| Headache and dizziness | 4% |
Finasteride
The grouping of finasteride adverse events has no overlap with minoxidil adverse events:
| Adverse event group | % of top 25 AEs |
| Sexual function | 31% |
| Psychological dimension | 29% |
| Sexual anatomy & physiology | 12% |
| Memory, cognition & attention | 10% |
| Energy & musculoskeletal system | 9% |
| Sleep | 5% |
| Sensory | 3% |
| Endocrine | 2% |
Here is the same grouping shown as treemaps:
Detailed data: Top 25 AEs of minoxidil and finasteride grouped by category
| Minoxidil | Finasteride |
| Skin reactions Application Site Pruritus – 45 Application Site Erythema – 24 Application Site Pain – 23 Pruritus – 28 Erythema – 18 Application Site Rash – 18 Rash – 14 Application Site Irritation – 14 Application Site Dryness – 14 Dry Skin – 11 Application Site Swelling – 11 Swelling Face – 10 Skin Irritation – 10 Skin Exfoliation – 10 Incorrect use of product Inappropriate Schedule Of Product Administration – 67 Product Administered At Inappropriate Site – 41 Product Use In Unapproved Indication – 30 Overdose – 28 Incorrect Dose Administered – 27 Underdose – 28 Wrong Technique In Product Usage Process – 11 Hair loss and drug effectiveness Alopecia – 84 Drug Ineffective – 38 Other Headache – 16 Dizziness – 11 | Sexual function Erectile Dysfunction – 398 Loss Of Libido / Libido Decreased – 366 Sexual Dysfunction – 100 Psychological dimension Depression – 276 Anxiety – 199 Suicidal Ideation – 136 Feeling Abnormal – 123 Panic Attack – 80 Sexual anatomy & physiology Testicular Pain – 96 Genital Hypoaesthesia [numbness] – 68 Penile Size Reduced – 59 Penis Disorder – 59 Ejaculation Disorder – 46 Memory, cognition & attention Amnesia / Memory Impairment – 124 Cognitive Disorder – 90 Disturbance In Attention – 63 Energy & musculoskeletal system Fatigue / Asthenia – 194 Muscle Atrophy – 68 Sleep Insomnia – 142 Sensory Tinnitus – 48 Vision Blurred – 44 Endocrine Gynaecomastia – 43 |