Dutasteride

Medication 5-alpha reductase inhibitor hormonal

Aka: Avodart, Duodart

Brands seen in Singapore: Avodart, Duodart, Dutaster, Dutasvitae, Intasteride

Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.

How to use

What it’s for

Prescribed for an enlarged prostate (bph), men only

When to take

HealthHub: once a day, with or without food

Take with

Water · HealthHub: swallowed whole, not chewed or opened

Pros & cons

Pros

HealthHub: lowers dht and shrinks the prostate
FDA label: one 0.5 mg capsule once daily
HealthHub: used alone or with tamsulosin

Cons

HealthHub: erection problems, lower libido
HealthHub: may take 6 months or more to notice
FDA: may raise the risk of high-grade prostate cancer

Sources

HSA — Listing of Registered Therapeutic Products (data.gov.sg open dataset, 5,511 rows, cached locally at /tmp/hsa_all.json and filtered locally) · read 2026-08-27
what it says
“All 11 registered dutasteride products carry Forensicclassification 'Prescription Only' — SIN12434P AVODART SOFT CAPSULE 0.5 mg · SIN14181P Duodart Capsules 0.5mg/0.4mg · SIN15882P DUTASTER · SIN15590P DUTASVITAE · SIN15563P INTASTERIDE”
HealthHub (Pharmaceutical Society of Singapore) — Dutasteride: what is this medication for · read 2026-08-27
what it says
“It lowers dihydrotestosterone, and thus shrinks the prostate and relieves the symptoms. Therefore, this medication is for use in men only. It may take up to 6 months or more for you to notice an effect.”
HealthHub — Dutasteride: how should I take or use this medication · read 2026-08-27
what it says
“You may take this medication with or without food. This medication should be swallowed whole; do not chew or open as contact with the contents of the capsules may make your mouth or throat sore.”
HealthHub — Dutasteride: what precautions should I take · read 2026-08-27
what it says
“Avoid donating blood during treatment or for 6 months after you stopped the treatment … Inform your healthcare professional if: You are allergic to this medication … You have heart or liver problem”
HealthHub — Dutasteride: common side effects · read 2026-08-27
what it says
“Unable to get or keep an erection firm enough to have sexual intercourse; Decreased libido (sex drive); Difficulty with ejaculation; Dizziness when taken in combination with tamsulosin”
US FDA label for dutasteride capsules, section 2 Dosage and Administration, via openFDA drug/label.json (effective 2026-08-14) · read 2026-08-27
what it says
“The recommended dose of dutasteride is 1 capsule (0.5 mg) taken once daily … Combination with tamsulosin: 0.5 mg once daily and tamsulosin 0.4 mg once daily … May take with or without food.”
US FDA label for dutasteride capsules, section 4 Contraindications, via openFDA · read 2026-08-27
what it says
“Dutasteride use is contraindicated in women who are pregnant … dutasteride may cause fetal harm when administered to a pregnant woman … clinically significant hypersensitivity … to dutasteride or other 5 alpha-reductase inhibitors”
US FDA label for dutasteride capsules, section 5 Warnings and Precautions, via openFDA · read 2026-08-27
what it says
“Dutasteride reduces serum prostate-specific antigen (PSA) concentration by approximately 50% … Dutasteride may increase the risk of high-grade prostate cancer … Patients should not donate blood until 6 months after their last dose”
US FDA label for dutasteride capsules, section 7 Drug Interactions, via openFDA · read 2026-08-27
what it says
“Use with caution in patients taking potent, chronic cytochrome P450 (CYP)3A4 enzyme inhibitors (e.g., ritonavir) … Coadministration of verapamil or diltiazem decreases dutasteride clearance and leads to increased exposure to dutasteride.”
US FDA label for dutasteride capsules, section 6 Adverse Reactions, via openFDA · read 2026-08-27
what it says
“Ejaculation disorders occurred significantly more in subjects receiving combination therapy (11%) compared with those receiving dutasteride (2%) or tamsulosin (4%) as monotherapy.”

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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.

In Singapore

Classification
HSA register

prescription-only

This is the Singapore classification, taken from the HSA register. Dosing stays with the label and your pharmacist or doctor — this page never tells you how much to take.

What the label says

The US FDA label for dutasteride states 'The recommended dose of dutasteride is 1 capsule (0.5 mg) taken once daily' and, in combination, '0.5 mg once daily and tamsulosin 0.4 mg once daily' — 0.5 mg once daily is the whole adult label range, with no higher step. every dutasteride product on the SG register is 0.5 mg. in Singapore the prescriber sets the dose.

Who should check first

Talk to a doctor or pharmacist before taking this if any of these apply to you.

Pregnancy: FDA: contraindicated in women who are pregnant
Women who are or may be pregnant should not handle the capsules (HealthHub, FDA)
Blood donation: HealthHub: not during, or for 6 months after, treatment
Heart or liver problems (HealthHub)

Documented interactions

With medicines and supplements

Ritonavir and other potent chronic CYP3a4 inhibitors: FDA: use caution — potential for drug-drug interactions; the effect has not been studied⁹
Verapamil or diltiazem: FDA: decrease dutasteride clearance and raise exposure; no dose adjustment is recommended⁹
Tamsulosin (combination therapy): FDA: ejaculation disorders occurred in 11% on combination vs 2% on dutasteride alone¹⁰
Psa blood testing: FDA: dutasteride reduces serum psa by about 50%, so a new psa baseline is needed⁸

Only combinations someone has written down appear here. A pair that is missing is unrecorded, not cleared.