Finasteride Contraindications
Finasteride is absolutely contraindicated in pregnancy and in women who may potentially become pregnant, as well as in individuals with hypersensitivity to any component of the medication. 1
Absolute Contraindications
Pregnancy and Women of Childbearing Potential
- Finasteride must never be used in pregnant women or women who may potentially become pregnant because it can cause abnormalities of the external genitalia in male fetuses by inhibiting the conversion of testosterone to dihydrotestosterone (DHT), which is necessary for normal male genital development. 1
- In animal studies, finasteride caused hypospadias in 3.6 to 100% of male offspring of pregnant rats at doses approximately 0.1 to 86 times the maximum recommended human dose, along with decreased prostatic and seminal vesicular weights, delayed preputial separation, and decreased anogenital distance. 1
- Pregnant women should not handle crushed or broken finasteride tablets because absorption through the skin could expose a male fetus to the drug; intact coated tablets are safe to handle as they prevent contact with the active ingredient during normal handling. 1
Hypersensitivity
- Finasteride is contraindicated in individuals with known hypersensitivity to any component of the medication. 1
Important Clinical Warnings (Not Absolute Contraindications)
Prostate Cancer Considerations
- Men aged 55 and over taking finasteride 5 mg/day have an increased risk of high-grade (Gleason score 8-10) prostate cancer (1.8% with finasteride vs 1.1% with placebo in the 7-year Prostate Cancer Prevention Trial). 1
- PSA levels are suppressed by approximately 50% after six months of finasteride therapy, requiring PSA values to be doubled for comparison with normal ranges in untreated men to preserve the utility of PSA screening for prostate cancer. 1
- Any confirmed increase from the lowest PSA value while on finasteride may signal prostate cancer and should be evaluated, even if PSA levels remain within the normal range for men not taking the drug. 1
Pediatric Population
- Finasteride is not indicated for use in pediatric patients. 1
Handling Precautions for Women
- Women who are pregnant or may potentially become pregnant should not handle crushed or broken finasteride tablets; if contact occurs, the area should be washed immediately with soap and water. 1
- Regarding semen exposure, finasteride concentrations in semen (ranging from undetectable to 21 ng/mL) are 50- to 100-fold less than the dose that had no effect on circulating DHT levels in men, representing minimal risk. 1
Obstructive Uropathy
- Patients with large residual urinary volume and/or severely diminished urinary flow should be carefully monitored for obstructive uropathy, as these patients may not be candidates for finasteride therapy. 1