From the Guidelines
Combining tamsulosin and tadalafil is not recommended due to the higher risk of side effects, particularly hypotension. According to the American Urological Association (AUA) guideline published in 2021 1, the combination of these two medications is not advised, especially considering the increased risk of adverse effects.
Potential Side Effects
- Hypotension (low blood pressure)
- Dizziness
- Lightheadedness
- Fainting
- Falls These side effects can be attributed to the additive or synergistic effects of both medications as vasodilators, with tamsulosin relaxing blood vessels in the prostate and bladder, and tadalafil dilating blood vessels throughout the body.
Patient Considerations
- Older adults
- Those with pre-existing cardiovascular conditions are at a higher risk for this interaction. Patients should be cautious when taking these medications together and follow their healthcare provider's instructions regarding dosing times, monitoring for symptoms of low blood pressure, and reporting any concerning symptoms promptly.
From the FDA Drug Label
Caution is advised when alpha adrenergic blocking agents including Tamsulosin Hydrochloride Capsules are co-administered with PDE5 inhibitors. Alphaadrenergic blockers and PDE5 inhibitors are both vasodilators that can lower blood pressure. Concomitant use of these two drug classes can potentially cause symptomatic hypotension
The potential side effect of combining tamsulosin (alpha-blocker) and tadalafil (phosphodiesterase type 5 inhibitor) is symptomatic hypotension. This is because both drug classes are vasodilators that can lower blood pressure, and their concomitant use can potentially cause a significant drop in blood pressure 2.
From the Research
Potential Side Effects of Combining Tamsulosin and Tadalafil
- The combination of tamsulosin (alpha-blocker) and tadalafil (phosphodiesterase type 5 inhibitor) may lead to hypotensive effects, as observed in a study where tadalafil augmented the hypotensive effect of doxazosin, another alpha-blocker 3.
- However, the same study found that tadalafil had little hemodynamic interaction with tamsulosin, suggesting a lower risk of hypotensive effects compared to doxazosin 3.
- A case study reported pronounced hypotension in a patient taking sildenafil and tamsulosin, highlighting the potential risk of hypotensive effects with combination therapy 4.
- Other studies have found that the combination of tamsulosin and tadalafil is generally well-tolerated, with common side effects including dyspepsia, heartburn, headache, flushing, myalgia, and backache 5, 6, 7.
- The incidence of adverse events was generally low, with no severe or serious adverse events reported in one study 6.
- A randomized, double-blinded, active-controlled trial found that the fixed-dose combination of tamsulosin and tadalafil was safe, well-tolerated, and efficacious, with a lower incidence of side effects compared to tadalafil monotherapy 7.
Hemodynamic Effects
- Tadalafil 20 mg augmented the hypotensive effect of doxazosin, producing a mean maximal decrease in standing systolic blood pressure (SBP) that was significantly greater than placebo 3.
- In contrast, tadalafil 10 and 20 mg produced mean maximal decreases in standing SBP that were similar to placebo when combined with tamsulosin 3.
- A case study reported a decrease in peripheral vascular resistance upon orthostasis during treatment with sildenafil and tamsulosin, leading to marked hypotension 4.
Clinical Implications
- The combination of tamsulosin and tadalafil may be a useful treatment option for patients with lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) 5, 6, 7.
- The fixed-dose combination of tamsulosin and tadalafil offers benefits in patient compliance and as add-on therapy in patients with comorbid BPH-associated LUTS and ED 7.
- However, patients should be monitored for potential hypotensive effects, particularly when combining tamsulosin with phosphodiesterase type 5 inhibitors like tadalafil 3, 4.