α-blocker + 5α-reductase inhibitor Pregnancy: Contraindicated for use by women. Dutasteride inhibits the conversion of testosterone to dihydrotestosterone and may, if administered to a woman carrying a male foetus, inhibit development of the external genitalia of the foetus; small amounts of dutasteride are recovered in semen, so when the patient's partner is or may potentially be pregnant it is recommended that the patient avoids exposing her to semen by using a condom (risk greatest during the first 16 weeks of pregnancy). It is not known whether dutasteride or tamsulosin are excreted in human milk. Dutasteride has been reported to reduce sperm count, semen volume and sperm motility, and reduced male fertility cannot be excluded.

Tamsulosin with dutasteride

Brand names: Combodart

This fixed-dose combination pairs the alpha-blocker tamsulosin with the 5-alpha-reductase inhibitor dutasteride for moderate-to-severe symptomatic benign prostatic hyperplasia, giving both rapid symptom relief and disease modification.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One capsule (dutasteride 0.5 mg / tamsulosin hydrochloride 0.4 mg) once daily

Route: Oral — swallow the capsules whole approximately 30 minutes after the same meal each day; the capsules should not be chewed or opened (contact with the contents of the dutasteride capsule may irritate the oropharyngeal mucosa)

Frequency: Once daily

The same dose applies to adults including the elderly; no higher dose is stated. Where appropriate the combination may be used to substitute concomitant dutasteride and tamsulosin hydrochloride in existing dual therapy to simplify treatment, and where clinically appropriate a direct change from dutasteride or tamsulosin hydrochloride monotherapy may be considered. Combination therapy should be prescribed after careful benefit-risk assessment because of the potential increased risk of adverse events (including cardiac failure) and after consideration of alternative treatment options including monotherapies. Renal impairment: no adjustment in dosage is anticipated. Hepatic impairment: caution in mild to moderate impairment; contraindicated in severe hepatic impairment. Paediatric population: contraindicated under 18 years of age. Monitoring: serum PSA decreases by approximately 50% after 6 months — a new PSA baseline should be established after 6 months and monitored regularly thereafter; digital rectal examination and other evaluations for prostate cancer must be performed before starting and periodically thereafter. Source: UK SPC for Combodart 0.5 mg / 0.4 mg hard capsules (eMC product 507); §4.4 and §4.8 were truncated at the source-fetch limit and no §4.5 interactions section was retrieved in this bundle.

Dose adjustments

Renal

No adjustment in dosage is anticipated for patients with renal impairment; the effect of renal impairment on dutasteride–tamsulosin pharmacokinetics has not been studied.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Women, and children and adolescents (under 18 years)
Hypersensitivity to dutasteride, other 5-alpha reductase inhibitors, tamsulosin (including tamsulosin-induced angio-oedema), soya, peanut or any of the other excipients
A history of orthostatic hypotension
Severe hepatic impairment

Side effects

Ejaculation disorders (common with the combination)
Impotence (common with the combination)
Altered (decreased) libido (common with the combination)
Breast disorders (common with the combination)
Dizziness (common with the combination); cardiac failure (uncommon with the combination). Tamsulosin-attributed reactions include syncope (rare), headache, palpitations, orthostatic hypotension, rhinitis, constipation, diarrhoea, nausea, vomiting (uncommon), angioedema (rare), Stevens-Johnson syndrome and priapism (very rare)

Clinical monograph

How it works

Tamsulosin relaxes prostatic and bladder-neck smooth muscle via selective alpha-1A adrenoceptor blockade, while dutasteride inhibits type-1 and type-2 5-alpha-reductase to lower dihydrotestosterone and shrink the prostate.

Prescribing in practice

Dutasteride is teratogenic and absorbed through skin, so the capsules must not be handled by women who are or may become pregnant, and treated men should not donate blood during therapy and for a defined period afterwards.
Tamsulosin can cause first-dose and postural hypotension and intra-operative floppy iris syndrome, so cataract surgeons must be told the patient is taking it.
Dutasteride approximately halves prostate-specific antigen, and this must be accounted for when interpreting PSA for prostate cancer screening.

Monitoring

Monitor symptom response, postural blood pressure and PSA trends interpreted against the expected dutasteride-related reduction.

Counselling the patient

Women who are or could become pregnant must not handle the capsules.
Rise slowly to avoid dizziness, and tell your eye surgeon you take this before any cataract operation.

Evidence & guidelines

The CombAT trial showed combined tamsulosin and dutasteride reduced symptom progression and acute urinary retention more than either agent alone in larger prostates.

Reference: NICE NG106; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways