GLP-1 Half-Life Visualizer

Select a medication and slide to any day to see the estimated drug level remaining in your system. Based on FDA-published half-life data. Educational tool — not medical advice.

Medication

t½ = 7 days — dosing every 7 days

Days since last injection: 3

Day 0Day 14Day 28

Estimated Serum Level — Day 3

74.3%of peak dose

High range — active

Concentration Decay Curve

>50% — Active range

10–50% — Declining

<10% — Near washout

Half-life data source: FDA Wegovy Prescribing Information §12.3

How This Works

Select Your Medication

Choose from semaglutide, tirzepatide, or liraglutide. Each has a distinct half-life from the FDA label.

Set Days Since Injection

Drag the slider to match how many days have passed since your last injection.

Read the Level

The tool estimates what percentage of the peak dose is still circulating, using the standard exponential decay formula.

Understand the Zones

Green = active range. Yellow = declining, next dose approaching. Red = near washout, minimal activity expected.

Half-Life Reference

Drug	Half-life	Dosing	Days to ~10% remaining	Source
Semaglutide	~7 days (168 h)	Once weekly	~23 days	FDA Wegovy §12.3
Tirzepatide	~5 days (116 h)	Once weekly	~16 days	FDA Zepbound §12.3
Liraglutide	~13 hours	Once daily	~1.8 days	FDA Saxenda §12.3

Half-life values reflect mean population estimates from FDA prescribing information. Individual values vary by body weight, renal function, and other factors.

What Does Half-Life Mean?

What is a drug half-life?

Half-life (t½) is the time it takes for the concentration of a drug in your bloodstream to fall to half its previous value. After one half-life, 50% remains. After two, 25%. After three, 12.5%. Most drugs are considered effectively cleared after 4–5 half-lives (~3–6% remaining).

Why does semaglutide stay in the body so long?

Semaglutide is chemically modified with a fatty-acid chain that binds to albumin in the blood. This slows clearance dramatically, giving it a half-life of ~7 days — much longer than the ~13 hours of older GLP-1 drugs like liraglutide. This is what makes once-weekly dosing possible.

Does a lower level mean the drug stopped working?

Not necessarily. Therapeutic effect depends on more than just concentration — receptor occupancy, downstream signaling, and individual response all matter. However, once levels fall significantly (below ~10–25% of peak), GLP-1 receptor activity is substantially reduced for most people. Talk to your prescriber if you notice increased hunger or side effects returning before your next dose.

Is this tool telling me what my actual blood level is?

No. This is an educational visualization based on average population pharmacokinetics from FDA label data. Actual serum levels vary significantly by individual. This tool is not a diagnostic device and should not be used to make any medical decisions.

Medical Disclaimer

This content is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations.

Always consult a qualified healthcare provider before starting, stopping, or modifying any treatment. Do not disregard professional medical advice based on information found on this site.

No claims of therapeutic efficacy are made for substances that are not FDA-approved for the discussed indications. Research citations reflect published findings and do not imply endorsement.