Adverse event data

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%
Psychological state
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 reactions40%
Incorrect use of product37%
Hair loss and drug ineffective19%
Headache and dizziness4%
Finasteride

The grouping of finasteride adverse events has no overlap with minoxidil adverse events:

Adverse event group% of top 25 AEs
Sexual function31%
Psychological dimension29%
Sexual anatomy & physiology12%
Memory, cognition & attention10%
Energy & musculoskeletal system9%
Sleep5%
Sensory3%
Endocrine2%

Here is the same grouping shown as treemaps:

Detailed data: Top 25 AEs of minoxidil and finasteride grouped by category
MinoxidilFinasteride
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