# Semaglutide: Half-Life, Dosing, and the Pharmacokinetics That Define It > Semaglutide is a once-weekly GLP-1 receptor agonist with a ~1-week elimination half-life. A documentation-grade digest of its pharmacokinetics, titration schedules, and trials, with every figure cited. A documentation-grade reading of the pharmacokinetics, the titration ladders, and the phase-3 trials behind them. Every quantitative claim cited. ## The short version Semaglutide is a man-made copy of a gut hormone called GLP-1 that your body releases after you eat. That hormone tells the pancreas to make insulin, tells the stomach to empty more slowly, and tells the brain you are full. Semaglutide does the same things, but it is built to last far longer: the natural hormone is gone in about two minutes, while semaglutide stays in the body for roughly a week. That long stay is the whole point of its design and the reason a single shot lasts seven days. Doctors prescribe it for type 2 diabetes, for long-term weight management, to lower heart-attack and stroke risk in certain people, and, since 2025, for a serious fatty-liver condition. It comes as a weekly injection under the skin and as a daily pill. The most common downside is stomach upset — nausea, in particular — especially when the dose is first raised. This site is a plain-English digest of the published research, organized around how the drug is dosed and why; what people report — including the downsides — is on [the effects page](/effects). ## What the pharmacokinetics actually show Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist — a drug that switches on the same receptor as the natural "I have eaten" hormone. Its defining property is duration. The elimination half-life (the time for the drug level in the blood to fall by half) is approximately one week, commonly cited as about 165 to 168 hours, with effectively complete clearance roughly five weeks after the final dose [13][15]. Native GLP-1, by contrast, is degraded in about two minutes. That difference is engineered. Semaglutide is a 31-amino-acid analogue sharing roughly 94% of its sequence with human GLP-1 [15]. Two changes do the work: an alpha-aminoisobutyric-acid substitution at position 8 blocks the enzyme DPP-4 (dipeptidyl peptidase-4, the protease that chews up the natural hormone), and a C18 fatty-di-acid side chain binds tightly but reversibly to albumin, the most abundant protein in blood. Albumin binding shields the peptide from the kidneys and slows its clearance — which is precisely why once-weekly dosing is possible. The full [semaglutide half life](/half-life) breakdown sits on its own page. ## What the trials measured The clinical record is large and consistent. In the STEP 1 trial (n=1,961 adults with overweight or obesity, without diabetes), once-weekly subcutaneous semaglutide 2.4 mg produced a mean body-weight change of -14.9% from baseline to week 68, versus -2.4% with placebo — a treatment difference of about 12.4 percentage points [1]. The cardiovascular and kidney outcomes are equally specific. In SUSTAIN-6 (n=3,297, type 2 diabetes at cardiovascular risk), semaglutide cut the composite of cardiovascular death, nonfatal heart attack, and nonfatal stroke (hazard ratio 0.74; 95% CI 0.58-0.95) [2]. SELECT (n=17,604, established cardiovascular disease without diabetes) showed a 20% relative risk reduction in the same composite (HR 0.80; 95% CI 0.72-0.90) [3]. FLOW (n=3,533, diabetes with chronic kidney disease) cut major kidney events by 24% (HR 0.76; 95% CI 0.66-0.88) [6]. Each of these is detailed, with its caveats, in the [Semaglutide research](/research) summary. ## How it is dosed in the studies Dosing in the trials is built around the slow titration that the long half-life and the gastrointestinal-tolerability profile require. For chronic weight management, the subcutaneous schedule in the label and the STEP program escalates over months: 0.25 mg once weekly for weeks 1-4, then 0.5 mg, 1.0 mg, 1.7 mg, and a 2.4 mg maintenance dose [1][15]. For type 2 diabetes the maintenance target is lower, typically 0.5 to 1.0 mg weekly, with up to 2.0 mg studied [15]. There is also a once-daily oral tablet, co-formulated with an absorption enhancer called SNAC, dosed 3 mg, then 7 mg, then 14 mg daily, taken fasted [11][23]. These are documented trial and label schedules, reported here as findings — not as instructions for any individual. The [oral semaglutide](/oral) page covers why the tablet works at all, and the [dosage research context](/dosage) page lays out every studied schedule. ## What to read next This digest is organized around the pharmacokinetics-dosing lens. If you want the duration math, start with the half-life page. If you want the human-interest layer — what people report and who should be cautious — the [Semaglutide effects](/effects) page is built from the safety literature and community reports, with the anecdotal material clearly labeled. The full citation list, with DOIs and PubMed links, is in the [Semaglutide references](/references). --- A documentation-grade reading of the semaglutide literature, indexed by half-life and dose; not a clinic, not a pharmacy, and nothing here prescribed or dispensed.