Silodosin

Highly selective α1A-adrenergic blocker

ATC code: G04CA04

Brand names: Rapaflo

Updated 26 May 2026 · Methodology

Indications

Benign prostatic hyperplasia

First line

First-line for symptomatic benign prostatic hyperplasia with moderate-to-severe symptoms per EAU 2024 alongside tamsulosin and alfuzosin. Dose 8 mg once daily. Effective on IPSS and Qmax. Particularly suitable in patients with orthostatic hypotension risk factors – less BP drop than tamsulosin. Does not reduce prostate size – with a large gland, combine with a 5α-reductase inhibitor (finasteride, dutasteride).

Sources

ICD-10: N40 · ICD-11: GA90

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Anti-aging and longevity

Not recommended

Silodosin is a highly selective α1A-adrenergic blocker. It is prescribed for men with benign prostatic hyperplasia (BPH) (AUA 2023, AEMPS Ficha Técnica). Silodosin is prescribed to men for anti-aging improvement of urination outside a BPH indication. No clinical studies of prophylactic use in this setting exist. The drug has pronounced retrograde ejaculation (in 28% of patients – abnormally frequent versus other α1-blockers), orthostatic hypotension, dizziness, and risk of intraoperative cataract surgery complications (intraoperative floppy iris syndrome). If silodosin was prescribed outside confirmed BPH, consider seeking a second opinion.

Sources

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

A highly selective α1A-adrenoceptor antagonist on prostate, bladder neck, and proximal urethra. α1A/α1B selectivity is 162:1 – much higher than tamsulosin's 16:1. This reduces hypotension and syncope risk but raises retrograde ejaculation rates (28% with silodosin vs 8% with tamsulosin per Yuan 2013 meta-analysis). Onset 3–4 hours after first dose. CYP3A4- and UGT2B7-metabolized.

Safety

Contraindications

Silodosin hypersensitivity
Severe renal impairment (eGFR under 30)
Severe hepatic impairment
Age under 18
Female sex (not prescribed)
Concomitant strong CYP3A4 inhibitors

Serious adverse effects

Intraoperative floppy iris syndrome (IFIS) during cataract surgery
Priapism (rare)
Anaphylaxis and angioedema (rare)

Common adverse effects

Retrograde ejaculation (28%)
Dizziness
Nasal congestion
Diarrhea
Orthostatic hypotension (less than tamsulosin)

Pregnancy: can you take Silodosin?

Not used in women.

Breastfeeding: can you take Silodosin?

Not used in women.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Timing and administration

Take once daily with food to reduce empty-stomach hypotensive effect. With eGFR 30–50, reduce dose to 4 mg; at eGFR under 30, contraindicated. Before cataract or glaucoma surgery, warn the ophthalmologist – intraoperative floppy iris syndrome (IFIS) risk. Do not combine with strong CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin).

Label mentions29 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

CriticalClarithromycin
«CONTRAINDICATIONS: Concomitant administration with strong Cytochrome P450 3A4 (CYP3A4) inhibitors (e.g., ketoconazole, clarithromycin, itraconazole, ritonavir) [see DRUG INTERACTIONS (7.1) ]»
FDA, section 4 · Open on DailyMed
CriticalItraconazole
«CONTRAINDICATIONS: Concomitant administration with strong Cytochrome P450 3A4 (CYP3A4) inhibitors (e.g., ketoconazole, clarithromycin, itraconazole, ritonavir) [see DRUG INTERACTIONS (7.1) ]»
FDA, section 4 · Open on DailyMed
CriticalKetoconazole
«CONTRAINDICATIONS: Concomitant administration with strong Cytochrome P450 3A4 (CYP3A4) inhibitors (e.g., ketoconazole, clarithromycin, itraconazole, ritonavir) [see DRUG INTERACTIONS (7.1) ]»
FDA, section 4 · Open on DailyMed
CriticalRitonavir
«CONTRAINDICATIONS: Concomitant administration with strong Cytochrome P450 3A4 (CYP3A4) inhibitors (e.g., ketoconazole, clarithromycin, itraconazole, ritonavir) [see DRUG INTERACTIONS (7.1) ]»
FDA, section 4 · Open on DailyMed
MajorCiclosporin
«Inhibidores de CYP3A4: En u n estudio de interacciones, se observó que las concentraciones plasmáticas máximas de silodosina aumentaban 3,7 veces y la exposición a dicho fármaco (es decir, el AUC)…»
AEMPS, section 4.5 · Open on CIMA
MajorCYP3A4 inhibitorsclass named in the label
«Moderate and Strong CYP3A4 Inhibitors: In a clinical metabolic inhibition study, a 3.8-fold increase in silodosin maximum plasma concentrations and 3.2-fold increase in silodosin exposure were…»
FDA, section 7 · Open on DailyMed
MajorItraconazole
«Inhibidores de CYP3A4: En u n estudio de interacciones, se observó que las concentraciones plasmáticas máximas de silodosina aumentaban 3,7 veces y la exposición a dicho fármaco (es decir, el AUC)…»
AEMPS, section 4.5 · Open on CIMA
MajorKetoconazole
«Inhibidores de CYP3A4: En u n estudio de interacciones, se observó que las concentraciones plasmáticas máximas de silodosina aumentaban 3,7 veces y la exposición a dicho fármaco (es decir, el AUC)…»
AEMPS, section 4.5 · Open on CIMA
MajorRitonavir
«Inhibidores de CYP3A4: En u n estudio de interacciones, se observó que las concentraciones plasmáticas máximas de silodosina aumentaban 3,7 veces y la exposición a dicho fármaco (es decir, el AUC)…»
AEMPS, section 4.5 · Open on CIMA
Moderateantagonistas del calcioclass named in the label
«Antihipertensivos: En el programa de ensayos clínicos, muchos pacientes estaban recibiendo tratamiento antihipertensivo concomitante (sobre todo fármacos con acción sobre el sistema…»
AEMPS, section 4.5 · Open on CIMA
Moderatebetabloqueantesclass named in the label
«Antihipertensivos: En el programa de ensayos clínicos, muchos pacientes estaban recibiendo tratamiento antihipertensivo concomitante (sobre todo fármacos con acción sobre el sistema…»
AEMPS, section 4.5 · Open on CIMA
ModerateDiltiazem
«Moderate and Strong CYP3A4 Inhibitors: In a clinical metabolic inhibition study, a 3.8-fold increase in silodosin maximum plasma concentrations and 3.2-fold increase in silodosin exposure were…»
FDA, section 7 · Open on DailyMed
Moderatediuréticosclass named in the label
«Antihipertensivos: En el programa de ensayos clínicos, muchos pacientes estaban recibiendo tratamiento antihipertensivo concomitante (sobre todo fármacos con acción sobre el sistema…»
AEMPS, section 4.5 · Open on CIMA
ModerateErythromycin
«Moderate and Strong CYP3A4 Inhibitors: In a clinical metabolic inhibition study, a 3.8-fold increase in silodosin maximum plasma concentrations and 3.2-fold increase in silodosin exposure were…»
FDA, section 7 · Open on DailyMed
Moderateinhibidores de la PDE5class named in the label
«Inhibidores de la PDE-5: Se han observado mínimas interacciones farmacodinámicas entre la silodosina y dosis máximas de sildenafilo o tadalafilo. En un ensayo controlado con placebo en el que…»
AEMPS, section 4.5 · Open on CIMA
Moderateinhibidores del CYP3A4class named in the label
«Inhibidores de CYP3A4: En u n estudio de interacciones, se observó que las concentraciones plasmáticas máximas de silodosina aumentaban 3,7 veces y la exposición a dicho fármaco (es decir, el AUC)…»
AEMPS, section 4.5 · Open on CIMA
ModeratePDE5 inhibitorsclass named in the label
«PDE5 Inhibitors: Co-administration of silodosin with a single dose of 100 mg sildenafil or 20 mg tadalafil was evaluated in a placebo-controlled clinical study that included 24 healthy male subjects…»
FDA, section 7 · Open on DailyMed
ModerateSildenafil
«Inhibidores de la PDE-5: Se han observado mínimas interacciones farmacodinámicas entre la silodosina y dosis máximas de sildenafilo o tadalafilo. En un ensayo controlado con placebo en el que…»
AEMPS, section 4.5 · Open on CIMA
ModerateSildenafil
«PDE5 Inhibitors: Co-administration of silodosin with a single dose of 100 mg sildenafil or 20 mg tadalafil was evaluated in a placebo-controlled clinical study that included 24 healthy male subjects…»
FDA, section 7 · Open on DailyMed
ModerateTadalafil
«Inhibidores de la PDE-5: Se han observado mínimas interacciones farmacodinámicas entre la silodosina y dosis máximas de sildenafilo o tadalafilo. En un ensayo controlado con placebo en el que…»
AEMPS, section 4.5 · Open on CIMA
ModerateTadalafil
«PDE5 Inhibitors: Co-administration of silodosin with a single dose of 100 mg sildenafil or 20 mg tadalafil was evaluated in a placebo-controlled clinical study that included 24 healthy male subjects…»
FDA, section 7 · Open on DailyMed
ModerateVerapamil
«Moderate and Strong CYP3A4 Inhibitors: In a clinical metabolic inhibition study, a 3.8-fold increase in silodosin maximum plasma concentrations and 3.2-fold increase in silodosin exposure were…»
FDA, section 7 · Open on DailyMed
MinorDiltiazem
«Inhibidores de CYP3A4: Cuando la silodosina se administró concomitantemente con un inhibidor de moderada potencia de CYP3A4, como el diltiazem, se observó un aumento del AUC de la silodosina de…»
AEMPS, section 4.5 · Open on CIMA
barbitúricosclass named in the label
«La silodosina se metaboliza de forma extensiva, principalmente a través de CYP3A4, alcohol deshidrogenasa y UGT2B7. La silodosina también es un sustrato de la glicoproteína P. Las sustancias que…»
AEMPS, section 4.5 · Open on CIMA
Carbamazepine
«La silodosina se metaboliza de forma extensiva, principalmente a través de CYP3A4, alcohol deshidrogenasa y UGT2B7. La silodosina también es un sustrato de la glicoproteína P. Las sustancias que…»
AEMPS, section 4.5 · Open on CIMA
Digoxin
«Digoxin: The effect of co-administration of silodosin and digoxin 0.25 mg/day for 7 days was evaluated in a clinical trial in 16 healthy males, aged 18 to 45 years. Concomitant administration of…»
FDA, section 7 · Open on DailyMed
Phenytoin
«La silodosina se metaboliza de forma extensiva, principalmente a través de CYP3A4, alcohol deshidrogenasa y UGT2B7. La silodosina también es un sustrato de la glicoproteína P. Las sustancias que…»
AEMPS, section 4.5 · Open on CIMA
Rifampicin
«La silodosina se metaboliza de forma extensiva, principalmente a través de CYP3A4, alcohol deshidrogenasa y UGT2B7. La silodosina también es un sustrato de la glicoproteína P. Las sustancias que…»
AEMPS, section 4.5 · Open on CIMA

From other drugs’ labels

Itraconazole
«Urológicos: Alfuzosina, Silodosina, Tadalafilo (disfunción eréctil e hiperplasia benigna de próstata), Tamsulosina, Tolterodina»
AEMPS, section 4.5 · Open on CIMA

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Frequently asked

What is Silodosin used for?

Silodosin is evaluated for the following indications with varying evidence strength: Benign prostatic hyperplasia (evidence tier A), Anti-aging and longevity (evidence tier F). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Silodosin?

Common side effects of Silodosin (≥ 1 in 100): Retrograde ejaculation (28%), Dizziness, Nasal congestion, Diarrhea, Orthostatic hypotension (less than tamsulosin). See the Safety section for uncommon and serious reactions.

Is Silodosin safe during pregnancy?

Not used in women.

Is Silodosin compatible with breastfeeding?

Not used in women.

Who should not take Silodosin?

Silodosin is contraindicated in: Silodosin hypersensitivity; Severe renal impairment (eGFR under 30); Severe hepatic impairment; Age under 18; Female sex (not prescribed). Full list in the Safety section.

Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMALabel dated 05/31/2023
EMALabel dated 01/29/2010
FDA / DailyMedLabel dated 08/18/2026

Other drugs in this group

Solifenacin, Tadalafil, Tamsulosin, Tolterodine, Vardenafil, Fesoterodine, Propiverine, Trospium