Find your best injection day and time
Your medicine level is lowest just before each injection and peaks about a day after. Inject the day before you’re most likely to overeat. For many people that makes Thursday or Friday a good start.
For people already prescribed tirzepatide. This tool doesn’t recommend a dose.
Tell us when you’re most at risk
The day and time work together, so answer both.
Your week
The line shows how much medicine is in your system. It rises for a day or two after each injection, then falls until the next.
The hatched band is when side effects are most likely, from about twelve hours after an injection to a few days later. The shaded column is the day you told us you are most at risk of overeating.
This is the average shape, not your exact levels. Body weight and how fast you clear the medicine change the height, not the shape.
To see the actual levels at your dose, use the concentration curve tool. Dose changes the height of the line, not the best day.
Side effects follow the same curve
Nausea usually starts 12 to 48 hours after an injection and is worst over the next few days. It’s most noticeable after starting or increasing a dose, and usually fades.
So the day with the most appetite help may also be the day you feel side effects most. Many people inject in the evening so the first night passes while they sleep.
Side effects are personal. The band on the chart shows when they’re most likely across many people, not a forecast for you.
This is about drug levels, not about effectiveness
No one has published the level at which appetite suppression fades, and it will be different for different people — which is why low doses work for some and not others. These tools are designed to let you understand how the drug levels typically behave, from the research we have.
Before changing your injection day
Talk to your prescriber first. Moving the day changes the gap between two doses.
Pick a day you’ll reliably remember. Consistency matters most.
Your body weight shifts the curve more than the day you choose. The figures and their source.
For people already prescribed tirzepatide. It doesn’t recommend a dose or replace your prescriber’s advice. If you feel unwell, contact your doctor or NHS 111.