Dutasteride + Tamsulosin

Fixed-dose combination: 5-alpha-reductase inhibitor plus selective alpha-1a-adrenoceptor blocker

ATC code: G04CA52(Tamsulosin and dutasteride)

Updated 24 Sep 2026 · Methodology

Indications

Benign prostatic hyperplasia

Second line

Benign prostatic hyperplasia in men with moderate-to-severe symptoms (IPSS ≥8), enlarged prostate (≥30 mL), and progression risk. Per EAU 2024 – second-line after alpha-blocker or 5-alpha-reductase inhibitor monotherapy. Dose: 0.5/0.4 mg once daily 30 minutes after a meal. Tamsulosin effect at 1–2 weeks, dutasteride at 3–6 months. PSA falls by 50% – adjust for this when interpreting results.

Sources

ICD-10: N40 · ICD-11: GA90

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

Dutasteride inhibits both 5-alpha-reductase isoforms (types 1 and 2) – blocks testosterone-to-dihydrotestosterone conversion, the main growth driver of prostatic tissue. Over 6–12 months reduces prostate volume by 20–25%. Tamsulosin selectively blocks alpha-1a adrenoceptors in bladder neck and prostate smooth muscle – rapidly relieves urinary obstruction (effect at 1–2 weeks). The combination provides more complete BPH control and reduces acute urinary retention and surgery risk vs monotherapy (CombAT 2010).

Safety

Contraindications

Hypersensitivity to components or other 5-alpha-reductase inhibitors
Severe orthostatic hypotension history
Severe hepatic impairment
Women and children
Contact of pregnant women with broken capsules (dutasteride teratogenicity)

Serious adverse effects

Allergic reactions and angioedema
Depression with suicidal thoughts (rare)
High-grade prostate cancer (Gleason 8–10) – rare risk per PCPT and REDUCE; maintain oncologic vigilance
Intraoperative floppy iris syndrome during cataract surgery

Common adverse effects

Retrograde ejaculation
Erectile dysfunction
Decreased libido
Gynecomastia
Dizziness
Orthostatic hypotension
Nasal congestion

Pregnancy: can you take Dutasteride + Tamsulosin?

Contraindicated in women at any age. Pregnant women must avoid contact with broken capsules – dutasteride is absorbed through skin and causes hypospadias in male fetuses. In men, dutasteride persists in semen up to 6 months after discontinuation.

Breastfeeding: can you take Dutasteride + Tamsulosin?

Indicated for men only – breastfeeding not applicable.

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 after a meal – reduces tamsulosin-related orthostatic hypotension. Do not crush or chew the capsule (extended release). For severe dizziness after the first dose, do not split – assess BP and ECG.

Drug interactions

Strong CYP3A4 inhibitors (clarithromycin, itraconazole) raise tamsulosin levels. PDE-5 inhibitors (sildenafil, tadalafil) increase hypotension risk – separate by 6 hours. Warn cataract surgeon (IFIS, intraoperative floppy iris syndrome).

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Frequently asked

What is Dutasteride + Tamsulosin used for?

Dutasteride + Tamsulosin is evaluated for the following indications with varying evidence strength: Benign prostatic hyperplasia (evidence tier A). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Dutasteride + Tamsulosin?

Common side effects of Dutasteride + Tamsulosin (≥ 1 in 100): Retrograde ejaculation, Erectile dysfunction, Decreased libido, Gynecomastia, Dizziness, Orthostatic hypotension. See the Safety section for uncommon and serious reactions.

Is Dutasteride + Tamsulosin safe during pregnancy?

Is Dutasteride + Tamsulosin compatible with breastfeeding?

Indicated for men only – breastfeeding not applicable.

Who should not take Dutasteride + Tamsulosin?

Dutasteride + Tamsulosin is contraindicated in: Hypersensitivity to components or other 5-alpha-reductase inhibitors; Severe orthostatic hypotension history; Severe hepatic impairment; Women and children; Contact of pregnant women with broken capsules (dutasteride teratogenicity). Full list in the Safety section.

Other drugs in this group

Fesoterodine, Finasteride, Mirabegron, Propiverine, Pygeum africanum, Solifenacin, Tolterodine, Pumpkin seed extract