Contraindications for Finasteride and Tamsulosin
Finasteride Contraindications
Finasteride is absolutely contraindicated in pregnancy or females who may potentially become pregnant, and in patients with hypersensitivity to any component of the medication 1.
Absolute Contraindications:
- Pregnancy or potential pregnancy in females: Finasteride can cause abnormalities of external genitalia in male fetuses due to inhibition of testosterone conversion to dihydrotestosterone 1.
- Hypersensitivity: Known hypersensitivity to finasteride or any component of the formulation 1.
Critical Safety Considerations (Not Absolute Contraindications but Important):
- Absence of prostatic enlargement: The AUA guidelines state that 5α-reductase inhibitors are NOT appropriate treatments for men with LUTS who do not have evidence of prostatic enlargement 2. This is a guideline-level recommendation against use rather than a formal contraindication.
- Handling precautions for females: Pregnant females or those who may potentially become pregnant should not handle crushed or broken finasteride tablets; intact coated tablets are safe to handle 1.
Additional Warnings:
- Increased risk of high-grade prostate cancer: Men aged 55+ with normal DRE and PSA ≤3.0 ng/mL taking finasteride 5 mg/day had increased risk of Gleason score 8-10 prostate cancer (1.8% vs 1.1% placebo) 1.
- PSA monitoring required: Finasteride reduces serum PSA by approximately 50% within 6 months, requiring adjusted interpretation for prostate cancer screening 1.
Tamsulosin Contraindications
Tamsulosin has only one absolute contraindication: known hypersensitivity to tamsulosin hydrochloride or any component of the formulation 3.
Absolute Contraindication:
- Hypersensitivity: Reactions have included skin rash, urticaria, pruritus, angioedema, and respiratory symptoms 3.
Important Clinical Considerations (Not Formal Contraindications):
- Intraoperative floppy iris syndrome (IFIS): Patients taking tamsulosin who undergo cataract surgery are at increased risk of IFIS, requiring ophthalmologic awareness 2.
- Cardiovascular concerns with doxazosin (not tamsulosin specifically): The AUA guidelines note that doxazosin monotherapy was associated with higher incidence of congestive heart failure compared to other antihypertensives in men with hypertension and cardiac risk factors, though this does not apply directly to tamsulosin 2.
Common Adverse Effects to Monitor:
- Orthostatic hypotension and dizziness: Though tamsulosin has a lower probability of orthostatic hypotension compared to other alpha-blockers 2.
- Ejaculatory dysfunction: Tamsulosin has a higher probability of ejaculatory dysfunction compared to other alpha-blockers 2, 4.
Key Clinical Distinctions
Finasteride has more restrictive contraindications due to teratogenic potential, while tamsulosin's only absolute contraindication is hypersensitivity 1, 3. The European Association of Urology guidelines emphasize that combination therapy with both agents increases adverse event rates typical of each drug class 2.