Caffeine Half-Life Tracker
Caffeine is an adenosine receptor antagonist. Its half-life in healthy adults is roughly 5 hours. If you drink a 200mg coffee at 3 PM, you still have 100mg in your system at 8 PM, and 50mg at 1 AM. This tool models plasma concentration decay.
Pharmacokinetics of Caffeine
Caffeine reaches peak plasma concentration (Cmax) between 15 to 120 minutes after ingestion. It is metabolized primarily in the liver by the cytochrome P450 oxidase enzyme system (specifically CYP1A2).
| Beverage | Avg Dose (mg) | Time to <25mg (assuming 5h half-life) |
|---|---|---|
| Espresso (Double) | 120mg | 11.3 hours |
| Filter Coffee (8oz) | 95mg | 9.6 hours |
| Energy Drink (16oz) | 160mg | 13.4 hours |
Common Mistakes
- "I can sleep after coffee": You might fall asleep, but polysomnography shows severely fragmented sleep architecture and reduced SWS (Slow-Wave Sleep).
- Ignoring hidden caffeine: Decaf coffee (2-15mg), dark chocolate (20-60mg), and pain relievers (up to 130mg).
FAQ
- Q: Does the half-life vary?
- A: Yes. Oral contraceptives can double the half-life (up to 10 hours), while smoking can cut it in half.