Where every number comes from.

The labels

• Wegovy (semaglutide) injection and tablets, prescribing information, Novo Nordisk, revised 06/2026

  Morning rules for the tablet (empty stomach, water up to 4 ounces, no other liquids, at least 30 minutes), the 30 day steps 1.5, 4, 9 and 25 mg, the missed dose sentence, the one week half-life, the pen's peak 1 to 3 days after the dose, the switch between tablet and injection.

• Wegovy tablets, FDA approved label, 2026

  Same document on the FDA site. Section 12.3: oral 25 mg concentrations comparable to the 2.4 mg weekly injection, with higher variability.

• Starting the Wegovy pill, patient page, Novo Nordisk

  The missed dose rule in patient words: skip that day's dose and take the scheduled dose the next day. The label itself adds: do not take more than one tablet per day.

• Rybelsus (semaglutide) tablets, prescribing information, Novo Nordisk, revised 01/2026

  The label Ozempic tablets inherit: morning rules, missed dose, steady state after 4 to 5 weeks of once daily tablets.

• Foundayo (orforglipron) tablets, FDA approved label, revised 07/2026

  No food or water rule, strengths 0.8 to 17.2 mg with at least 30 days per step, half-life 29 to 49 hours, steady state after about a week.

• Zepbound (tirzepatide) injection, prescribing information, Eli Lilly, revised 8/2026

  Half-life about 5 to 6 days, peak a median 24 hours after the shot (8 to 72 hours), steady state after 4 weeks of weekly shots.

• Mounjaro (tirzepatide) injection, prescribing information, Eli Lilly, revised 8/2026

  Half-life about 5 days, peak 8 to 72 hours after the shot, steady state after 4 weeks of weekly shots.

• Ozempic (semaglutide) injection, prescribing information, Novo Nordisk, revised 05/2026

  Half-life about 1 week, peak 1 to 3 days after the shot, steady state after 4 to 5 weeks of weekly shots.

• Trulicity (dulaglutide) injection, prescribing information, Eli Lilly, revised 3/2026

  Half-life about 5 days, peak 24 to 72 hours after the shot at steady state (median 48 hours), steady state within 2 to 4 weeks of weekly shots.

Absorption studies

• FDA Clinical Pharmacology Review, NDA 213051 (oral semaglutide), 2019

  Figure 12 (study 3794): exposure after a 15, 30, 60 and 120 minute post-dose fast. Figure 13 (study 3957): 50, 120 and 240 mL of water. Study 4154: 14 of 26 volunteers with no measurable drug when the tablet was taken with food.

• Bækdal TA et al. Effect of Various Dosing Conditions on the Pharmacokinetics of Oral Semaglutide. Diabetes Ther 2021;12(7):1915

  The same trial, peer reviewed: 15 minutes versus 30 minutes gives an exposure ratio of 0.50 [0.36; 0.70]; 60 minutes 1.25 (not significant); 120 minutes 1.68 [1.20; 2.34].

• van Hout M et al. Effect of Various Dosing Schedules on the Pharmacokinetics of Oral Semaglutide. Clin Pharmacokinet 2023;62:635

  Pre-dose fasting of 2, 4 or 6 hours instead of overnight: exposure 56 to 88 percent lower.

• European Medicines Agency, Rybelsus assessment report EMA/95374/2020

  Food or more than 120 mL of water in the stomach reduces absorption; waiting less than 30 minutes may decrease it. The dog data in that report are not used for humans.

Trials and cohorts

• Wharton S et al. Oral semaglutide 25 mg in adults with overweight or obesity (OASIS 4). N Engl J Med 2025

  The pivotal trial of the Wegovy pill. Numbers from it appear on this site only with the trial named.

• Marshall et al. Persistence on Wegovy and Zepbound, US insured adults without diabetes, n = 33 607. J Manag Care Spec Pharm 2026;32(3):281

  One-year persistence between 33 and 61 percent depending on the start year.

• DiStefano et al. Why adults stop a GLP-1, national survey, n = 440. J Manag Care Spec Pharm 2026;32(8):903

  Reasons for stopping: cost, side effects, coverage, goal reached; 55 percent stop within six months.

How the level chart is computed

Oolite draws the level as a percent of the steady state of the current dose step, never in milligrams. It is a one-compartment accumulation with a fixed half-life from the label: one dose is added each morning the tablet is taken, and the level decays by a factor of 2 to the power of minus one over the half-life in days, every day. A morning cut short before the label's 30 minutes counts as missed. The days between the start given in the app and the first logged dose count as taken, so the curve does not start from zero for someone already on a dose.

• Semaglutide tablets (Wegovy pill, Ozempic tablets, Rybelsus): half-life 7 days. One day without a tablet lowers the level by about 9 percent (2 to the power of minus one seventh is 0.906). The model reaches 90 percent of steady state on day 24 and 97 percent at five weeks, which matches the four to five weeks of the Rybelsus and Ozempic tablets label; the Wegovy label gives no delay for the tablet.
• Foundayo (orforglipron): half-life 1.6 days, close to the midpoint of the label's 29 to 49 hours (39 hours). One day without a tablet lowers the level by about 35 percent. The model reaches 90 percent of steady state on day 6, which matches the label's about one week.
• Weekly shots (Wegovy and Ozempic pens, Zepbound, Mounjaro, Trulicity): each shot adds a wave that rises to its peak at the label's time to maximum concentration, then decays by the label's half-life, and the level is a percent of the crest of the steady weekly wave. Values used: semaglutide 7 days and 2 days to peak (labels: about 1 week, 1 to 3 days); Zepbound 5.5 days and 24 hours (label: about 5 to 6 days, median 24 hours); Mounjaro 5 days and 24 hours (label: about 5 days, 8 to 72 hours; the 24 hours are the Zepbound median, same molecule); Trulicity 5 days and 48 hours (label: about 5 days, median 48 hours at steady state). Compounded shots have no label, so no level is drawn for them.

This is a model from the label's numbers, not a measurement of anyone's blood. Oral absorption varies too much from one morning to the next to show a blood value, which is why the chart shows a percent and never a concentration.