How much does dutasteride build up with daily dosing?

At steady state on a daily schedule, the model's level is about 51 times what one dose gives, and it swings about 1.02:1 between the peak and the trough before the next dose. Longer gaps between doses mean less build-up and a bigger swing.

Is this chart my actual dutasteride level?

No. It is a modeled estimate from a published half-life, using the same one-compartment model as the Dose Track app. Real levels vary with body weight, food, kidney and liver function and other factors, and only a lab test measures them. It is not medical advice.

Dutasteride Half-Life: Peak and Steady State Chart

Q: When does dutasteride peak after a dose?

Blood levels peak about 2.8 hours after a dose by mouth, according to Avodart (dutasteride) label. Individual timing varies with food, the amount and the person.

Q: How long does dutasteride take to reach steady state?

About 175 days (~25 weeks) of regular dosing at the same amount and interval, which is 5 half-lives. With a half-life of about 35 days (~5 weeks), levels reach about 50% of steady state after 35 days (~5 weeks) and about 90% after 116 days (~16.6 weeks). Changing the dose or interval starts a new climb toward a new steady state.

Q: How long does dutasteride stay in your system after the last dose?

Roughly 5 half-lives, about 175 days (~25 weeks), until about 97% has cleared in the model. Half is gone about 35 days (~5 weeks) after levels start falling. Real clearance varies from person to person, and a drug can still have effects after levels are low.

Short answer: Dutasteride has a half-life of about 35 days (~5 weeks) (Avodart (dutasteride) label) and reaches steady state after about 175 days (~25 weeks) of regular dosing. Levels peak about 2.8 hours after a dose by mouth. On a daily schedule the model builds up to about 51× a single dose, with a peak-to-trough swing of about 1.02:1.

What do dutasteride levels look like with daily dosing?

The Avodart label dose is 0.5 mg once daily (BPH); the label says levels reach about 90% of steady state after 3 months. Use for hair loss is off-label. Source: Avodart (dutasteride) label. Bioavailability 60% as in the app. Dashed line: 5 half-lives. Change the amount or schedule in the calculator.

When does dutasteride peak after a dose?

Levels peak about 2.8 hours after a dose by mouth.

How long does dutasteride take to reach steady state?

With regular dosing at a fixed amount and interval, levels climb toward steady state by the same fraction every half-life, whatever the dose. At a half-life of about 35 days (~5 weeks):

Time from the first dose to each share of steady state, dutasteride (half-life 5 weeks).
Share of steady state	Half-lives	Time
50%	1	35 days (~5 weeks)
75%	2	70 days (~10 weeks)
90%	3.3	116 days (~16.6 weeks)
97% (Dose Track's steady-state rule)	5	175 days (~25 weeks)

How much do dutasteride levels swing between doses?

The longer the gap between doses compared with the half-life, the bigger the swing from peak to trough and the less the levels build up. These ratios do not depend on the amount.

Steady-state peak:trough and build-up by dosing interval, dutasteride, in Dose Track's model.
Interval	Peak : trough	Build-up vs one dose
Daily	1.02 : 1	51×
Every other day	1.04 : 1	25.75×
Twice weekly	1.07 : 1	14.93×
Weekly	1.15 : 1	7.73×
Every 2 weeks	1.32 : 1	4.13×

Build-up is the accumulation ratio 1 / (1 − e^−k·τ), with k = ln 2 / half-life and τ the interval.

How long does dutasteride stay in your system?

After the last dose, about half is gone every 5 weeks. After 5 half-lives, about 175 days (~25 weeks), roughly 97% has cleared in the model.

Where do these numbers come from?

The FDA Avodart label gives a terminal half-life of about 5 weeks at steady state; Dose Track uses 35 days. Peak levels come 2 to 3 hours after a dose; the app uses 2.8 hours. Levels reach about 65% of steady state after 1 month and 90% after 3 months, and stay detectable for 4 to 6 months after stopping.

Avodart (dutasteride) prescribing information, sections 1, 2, 3, 5 and 12.3. DailyMed, 2025.

The curve uses the half-life, time to peak, route and bioavailability built into the Dose Track app for dutasteride, and the same one-compartment model with first-order absorption. These are modeled estimates from published half-lives, drawn with the same one-compartment model as the Dose Track app. Real levels vary from person to person, and only a lab test measures them. This is not medical advice and not a dosing recommendation; dosing decisions belong with you and your prescriber.

Vial sizes and syringe math are in the Dutasteride guide.

When does dutasteride peak and reach steady state?