Prescription ·Strong evidence ·Reviewed May 2026
Silodosin is an oral alpha-1A adrenergic blocker used to improve lower urinary tract symptoms from benign prostatic hyperplasia. It relaxes smooth muscle in the prostate, bladder neck, and urethra, but can cause orthostatic hypotension, dizziness, and a high rate of ejaculatory dysfunction; strong CYP3A4 inhibitors and severe renal or hepatic impairment are important safety limits.
The bottom line
Evidence rating strong. Most-documented uses: improved urinary flow in benign prostatic hyperplasia, reduced incomplete emptying sensation, reduced weak stream and hesitancy. 3 sources indexed (2009–2026), with 4 interaction records on file.
Core mechanism
Silodosin selectively antagonizes alpha-1A receptors that mediate contraction of smooth muscle in the prostate, bladder base, bladder neck, prostatic capsule, and urethra. Blocking these receptors reduces dynamic outlet obstruction and improves urine flow. The drug is metabolized by UGT2B7, alcohol and aldehyde dehydrogenases, CYP3A4, and P-glycoprotein pathways, making renal impairment and CYP3A4/P-glycoprotein interactions clinically relevant.1,2
Take with a meal to reduce peak-related adverse effects and maintain consistent absorption. Capsules may be opened and sprinkled on applesauce when needed according to labeling.3
L-citrulline can increase nitric oxide availability and may add to silodosin-related dizziness or orthostatic hypotension.
Recommendation: Use cautiously when starting or titrating silodosin; monitor standing dizziness and falls.
Saw palmetto is often used for urinary symptoms and may overlap with silodosin goals, but evidence is less consistent than prescription alpha blockers.
Recommendation: Do not substitute saw palmetto for prescribed BPH evaluation; monitor dizziness and symptom response if combined.
High-dose quercetin may inhibit CYP3A4 or P-glycoprotein and could increase silodosin exposure.
Recommendation: Monitor for dizziness, low blood pressure, or ejaculatory adverse effects when starting or stopping high-dose quercetin.
St. John's Wort can induce CYP3A4 and P-glycoprotein and may reduce silodosin exposure.
Recommendation: Avoid unsupervised use if urinary symptom control depends on silodosin.
Numbered references. Citations throughout the page link here.
Clinical trials showed symptom score and urinary flow improvements, with ejaculatory dysfunction and dizziness as common adverse effects.
Guideline supports alpha blockers for bothersome LUTS/BPH and highlights individualized adverse-effect selection.
Labeling describes 8 mg daily with meal dosing, renal dose reduction, strong CYP3A4 contraindication, orthostatic effects, and ejaculation adverse effects.
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