How long a compound stays in your system

The blood level falls to a few percent of its peak after about five and a half half-lives. That puts an oral at a couple of days and a long ester at several months — and it is a different question from how long a test can detect it.

Short answer

Take five and a half half-lives after the last dose and the serum level has fallen to roughly 2% of its peak. On that basis an oral like Dianabol (5.3 hours) is effectively gone within a couple of days, testosterone propionate (24.9 hours) within a week, testosterone enanthate (7.2 days) in about six weeks, and testosterone undecanoate (20 days) in around four months. None of these are detection windows: drug tests look for metabolites, which persist long after the parent compound has cleared the blood.

The arithmetic

Each half-life removes half of what is left. One takes you to 50% of the peak, two to 25%, three to 12.5%, four to about 6%, five to about 3%, five and a half to roughly 2%. There is no point at which the number reaches zero — it approaches it — so any answer to "how long" is a choice about how low is low enough.

Five to five and a half half-lives is the convention, and it is the same convention that puts steady state at five half-lives on the way up. The curve is symmetric that way: a schedule takes as long to clear as it took to settle.

Orals clear in days, long esters in months

The spread across compounds is enormous. Oral half-lives run in hours — Dianabol 5.3 hours, Anavar 6.7 hours, Anadrol 8 hours, Winstrol 9 hours — so the blood level is gone within a day or two of the last tablet.

Injectables run in days, and the range inside that is wide. Trenbolone acetate at 36 hours clears in about 8.3 days. Nandrolone decanoate at 10.2 days takes about 8 weeks. Testosterone undecanoate in castor oil, at 33.9 days, takes roughly 26.6 weeks — half a year, from a single dose of a single compound.

Dianabol

Testosterone Propionate

Nandrolone Decanoate

One dose of each over sixty days, scaled to its own peak. The oral has gone before the axis has properly started.

Blood level is not detection window

These are two genuinely different questions and conflating them is the most common mistake made with this number. The serum curve tracks the parent compound in your blood. A drug test looks for metabolites in urine, which are produced as the compound is broken down and which can be found for far longer — for some compounds, many months after the blood level is indistinguishable from zero.

Nothing on this site models metabolites, and nothing here should be read as an estimate of what a test will or will not find.

Common questions

How long does testosterone stay in your system?

It depends entirely on the ester. Propionate (24.9 hours half-life) clears the blood in about a week, enanthate (7.2 days) in around six weeks, and undecanoate (20 days) in about four months, on the five-and-a-half half-life convention.

How long do oral steroids stay in your system?

Days, not weeks. Oral half-lives are measured in hours — Dianabol 5.3 hours, Anavar 6.7 hours, Winstrol 9 hours — so the blood level has effectively cleared within a day or two of the last dose.

Is this how long a drug test can detect it?

No. Testing detects metabolites in urine, not the parent compound in blood, and metabolites are found long after the serum level has fallen away — for some compounds by many months. This model says nothing about detection.