Finasteride Side Effects

Not all side effects for finasteride may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to finasteride: oral tablet

In addition to its needed effects, some unwanted effects may be caused by finasteride. In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking finasteride:

More common
  • Chills
  • cold sweats
  • confusion
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position
Less common
  • Bloating or swelling of the face, arms, hands, lower legs, or feet
  • breast enlargement and tenderness
  • hives or welts
  • itchy skin
  • rapid weight gain
  • redness of the skin
  • skin rash
  • swelling of the lips and face
  • tingling of the hands or feet
  • unusual weight gain or loss
Incidence not known
  • Clear or bloody discharge from the nipple
  • dimpling of the breast skin
  • inverted nipple
  • lump in the breast or under the arm
  • persistent crusting or scaling of the nipple
  • redness or swelling of the breast
  • sore on the skin of the breast that does not heal

Some of the side effects that can occur with finasteride may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Decreased interest in sexual intercourse
  • inability to have or keep an erection
  • loss in sexual ability, desire, drive, or performance
Less common
  • Runny nose
  • sleepiness or unusual drowsiness
  • sneezing
  • stuffy nose
Less common or rare
  • Abdominal or stomach pain
  • back pain
  • decreased amount of semen
  • diarrhea
  • dizziness
  • headache
Incidence not known
  • Testicular pain

For Healthcare Professionals

Applies to finasteride: oral tablet

Genitourinary

Most men were older and were taking concomitant medications and/or had comorbid conditions:
Very common (10% or more): Impotence (up to 18.5%)
Common (1% to 10%): Abnormal ejaculation, decreased ejaculatory volume, abnormal sexual function, gynecomastia, erectile dysfunction, ejaculation disorder, testicular pain, male infertility and/or poor seminal quality[Ref]

Two hundred fourteen reports of gynecomastia in men taking finasteride in the United States were received by the FDA between June 1992 and February 1995. Among those reported, fifty eight percent were taking additional medications that have been associated with gynecomastia. Sixty nine of 86 patients who discontinued finasteride treatment had partial or complete remission.

New reports of drug-related sexual adverse experiences have been reported to decrease with duration of therapy.

Erectile dysfunction has been reported to continue beyond treatment discontinuation. Normalization or improvement of seminal quality has been reported after withdrawing finasteride treatment.[Ref]

Endocrine

Finasteride may cause a decrease in PSA levels in patients with benign prostatic hyperplasia as well as in patients with prostate cancer. In one study, mean PSA reductions of 50% were noted, regardless of baseline levels. There was no indication that PSA levels were further suppressed in patients with prostate cancer.

PSA levels are commonly used in the screening process for prostate cancer. Patients who develop sustained increases in PSA while on finasteride therapy should be carefully evaluated for medical causes as well as noncompliance.[Ref]

Uncommon (0.1% to 1%): Breast tenderness, breast enlargement
Frequency not reported: Reductions in prostate specific antigen (PSA) levels of approximately 50%[Ref]

Nervous system

Common (1% to 10%): Decreased libido, dizziness, somnolence
Frequency not reported: Headache[Ref]

Cardiovascular

Common (1% to 10%): Postural hypotension, hypotension
Postmarketing reports: Palpitations[Ref]

Oncologic

Frequency not reported: A prevention or delay in the appearance of prostate cancer, an increased risk of high-grade prostate cancer
Postmarketing reports: Rare cases of male breast cancer[Ref]

Gastrointestinal

Frequency not reported: Nausea, flatulence, abdominal pain[Ref]

Dermatologic

A 58 year old man presented with an itchy, lumpy rash on upper and lower extremities following two weeks of finasteride treatment for prostatism. The patient had no known allergies and was taking no other medications prior to the episode. The finasteride was discontinued and dapsone was initiated. The rash resolved two weeks after finasteride therapy was stopped.[Ref]

Rare (less than 0.1%): Rash
Very rare (less than 0.01%): Cutaneous leukocytoclastic vasculitis, solitary fixed drug eruption
Postmarketing reports: Pruritus, urticaria, angioedema (including swelling of the lips, tongue, throat, and face)[Ref]

Hypersensitivity

Frequency not reported: Pruritus, urticaria, angioedema of the lips, tongue, throat, and face[Ref]

Metabolic

Common (1% to 10%): Edema[Ref]

Respiratory

Uncommon (0.1% to 1%): Rhinitis, dyspnea[Ref]

Psychiatric

Frequency not reported: Depression

Musculoskeletal

Frequency not reported: Asthenia

Hepatic

Frequency not reported: Increased hepatic enzymes

References

1. "Product Information. Proscar (finasteride)." Merck & Co, Inc, West Point, PA.

2. Steiner JF "Finasteride: a 5 alpha-reductase inhibitor." Clin Pharm 12 (1993): 15-23

3. Gormley GJ, Stoner E, Bruskewitz RC, Imperato-McGinley J, Walsh PC, McConnell JD, Andriole GL, Geller J, Bracken BR, Tenover JS, et al "The effect of finasteride in men with benign prostatic hyperplasia. The Finasteride Study Group." N Engl J Med 327 (1992): 1185-91

4. Tammela TL, Kontturi MJ "Urodynamic effects of finasteride in the treatment of bladder outlet obstruction due to benign prostatic hyperplasia." J Urol 149 (1993): 342-4

5. Ferrando J, Grimalt R, Alsina M, Bulla F, Manasievska E "Unilateral Gynecomastia Induced by Treatment With 1 mg of Oral Finasteride." Arch Dermatol 138 (2002): 543-4

6. Green L, Wysowski DK, Fourcroy JL "Gynecomastia and breast cancer during finasteride therapy." N Engl J Med 335 (1996): 823

7. Stoner E "5 alpha-reductase inhibitors/finasteride." Prostate Suppl 6 (1996): 82-7

8. Guess HA, Heyse JF, Gormley GJ "The effect of finasteride on prostate-specific antigen in men with benign prostatic hyperplasia." Prostate 22 (1993): 31-7

9. Guess HA, Gormley GJ, Stoner E, Oesterling JE "The effect of finasteride on prostate specific antigen: review of available data." J Urol 155 (1996): 3-9

10. Stoner E, Round E, Ferguson D, Gormley GJ "Clinical experience of the detection of prostate cancer in patients with benign prostatic hyperplasia treated with finasteride." J Urol 151 (1994): 1296-300

11. Volpi R, Maccarini PA, Boni S, Chiodera P, Coiro V "Finasteride-induced gynecomastia in a 62-year-old man." Am J Med Sci 309 (1995): 322-5

12. Thompson IM, Goodman PJ, Tangen CM, et al. "The influence of finasteride on the development of prostate cancer." N Engl J Med 349 (2003): 215-24

13. Australian Government. Department of Health. Therapeutic Goods Administration "Medicines Safety Update, Volume 4, Number 6, December 2013. Available from: URL: http://www.tga.gov.au/hp/msu-2013-06.htm." ([2013 Dec]):

14. Oyama N, Kaneko F "Solitary fixed drug eruption caused by finasteride." J Am Acad Dermatol 60 (2009): 168-9

15. Lear JT, Byrne JPH "Finasteride-related cutaneous vaculitis." Postgrad Med J 72 (1996): 127

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