The condition reached when the rate of drug administration equals the rate of drug elimination, producing consistent blood concentrations over time. For any fixed dosing schedule, steady state is typically achieved after approximately five half-lives.

Before steady state, blood levels fluctuate more unpredictably. After steady state, each dose produces a predictable peak and trough. This concept matters for peptide protocols because clinical trial results are often measured at steady state—meaning the reported effects reflect what happens after the body has equilibrated, not what happens after a single dose. For peptides with long half-lives (like CJC-1295 with DAC at ~8 days), reaching steady state can take over a month of consistent dosing.