Proscar Side Effects

Generic name: finasteride

Medically reviewed by Drugs.com. Last updated on Feb 19, 2024.

Note: This document provides detailed information about Proscar Side Effects associated with finasteride. Some dosage forms listed on this page may not apply specifically to the brand name Proscar.

Applies to finasteride: oral tablet.

Serious side effects of Proscar

Along with its needed effects, finasteride (the active ingredient contained in Proscar) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking finasteride:

More common side effects

• chills
• cold sweats
• confusion
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position

Less common side effects

• bloating or swelling of the face, arms, hands, lower legs, or feet
• breast enlargement and tenderness
• hives or welts, itching, skin rash
• rapid weight gain
• redness of the skin
• 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

Other side effects of Proscar

Some side effects of finasteride may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common side effects

• decreased interest in sexual intercourse
• inability to have or keep an erection
• loss in sexual ability, desire, drive, or performance

Less common side effects

• runny or stuffy nose
• sleepiness or unusual drowsiness
• sneezing

Less common or rare side effects

• back pain
• decreased amount of semen
• diarrhea
• dizziness
• headache
• stomach pain

Incidence not known

• testicular pain

For healthcare professionals

Applies to finasteride: oral tablet.

Genitourinary adverse events

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
• Postmarketing reports: Hematospermia^[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

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

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]

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

• 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]

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]

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

Further information

Proscar side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer