Tadalafil (Cialis) is NOT contraindicated with finasteride—in fact, they are specifically approved for combined use.
The FDA explicitly approves the combination of tadalafil and finasteride for treating benign prostatic hyperplasia (BPH), with the combination marketed as a single formulation. 1 The FDA label for Cialis states that when used with finasteride to initiate BPH treatment, the combination is recommended for up to 26 weeks, after which the incremental benefit of tadalafil decreases.
Key Points About This Combination
FDA-Approved Use
- Tadalafil 5 mg once daily combined with finasteride 5 mg once daily is an FDA-approved regimen 1
- This combination is specifically indicated for men with BPH-related lower urinary tract symptoms (LUTS) and prostate enlargement (>30 mL) 1
- The combination provides early symptom improvement compared to finasteride alone 2
Clinical Evidence Supporting Safety
Multiple high-quality randomized controlled trials demonstrate that tadalafil/finasteride combination therapy is:
- Safe and well-tolerated with low incidence of sexual adverse events (only 5 patients on combination vs 7 on placebo/finasteride reported sexual side effects) 3
- More effective than finasteride alone for improving LUTS, with statistically significant improvements at 4,12, and 26 weeks 2
- Beneficial for sexual function, actually improving erectile function scores rather than causing the sexual dysfunction typically associated with finasteride monotherapy 3, 4
Practical Dosing
When combining these medications 1:
- Start tadalafil 5 mg once daily with finasteride 5 mg once daily
- Take at approximately the same time each day
- Continue for up to 26 weeks for BPH treatment initiation
- No dose adjustment needed for the combination itself
Important Caveats
Actual Contraindications for Tadalafil
The real contraindications you need to watch for are 1:
- Nitrates (any form)—absolute contraindication due to severe hypotension risk
- Guanylate cyclase stimulators (like riociguat)
- Severe hepatic impairment (Child-Pugh Class C)
- Known hypersensitivity to tadalafil
Drug Interactions Requiring Dose Adjustment
- Potent CYP3A4 inhibitors (ketoconazole, ritonavir): reduce tadalafil to maximum 2.5 mg daily when using once-daily dosing 1
- Alpha-blockers: patients should be stable on alpha-blocker therapy before starting tadalafil for ED; however, tadalafil is NOT recommended in combination with alpha-blockers specifically for BPH treatment 1
Renal Impairment Adjustments
For once-daily tadalafil with finasteride 1:
- CrCl 30-50 mL/min: start at 2.5 mg, may increase to 5 mg
- CrCl <30 mL/min or hemodialysis: once-daily use not recommended
Clinical Bottom Line
Not only is this combination not contraindicated, it represents a rational therapeutic strategy 5, 6. The combination may be particularly valuable for men who want to avoid the sexual side effects of finasteride monotherapy, as tadalafil actually counteracts finasteride-induced erectile dysfunction 3. However, some experts argue this represents a "prescribing cascade" and that other alternatives should be considered first in the context of polypharmacy concerns 7.
The ideal candidate for this combination is a man with prostate volume >30 mL, moderate-to-severe LUTS (IPSS ≥13), who desires additional benefit over monotherapy and would benefit from improved erectile function 6.