RSS Feed (xml)

Powered By

Skin Design:
Free Blogger Skins

Powered by Blogger

Wednesday, October 1, 2008

Caffeine's Half Life

The half life of caffeine (the time needed to excrete half the ingested dose) is 3-4 hours in healthy individuals. This means that even three to four hours after drinking coffee, half of it is still active in your system. The full excretion of the caffeine is due to the cytochrome P450 enzyme system in the liver. Caffeine is not only still in the system but it is still in the blood and tissues of the body. This may be desirable if one is hoping to stay alert. But it may prove difficult for those not accustomed to caffeine and it may disturb sleep. After 20 years not drinking coffee, I had two cups yesterday. The result: I awoke at 4:00 a.m. this morning.

  • Biochem Pharmacol. 1992 Jan 22;43(2):225-35. Biotransformation of caffeine and theophylline in mammalian cell lines genetically engineered for expression of single cytochrome P450 isoforms. Fuhr U, Doehmer J, Battula N, Wölfel C, Kudla C, Keita Y, Staib AH. (Accessed 10/1/08.)


Anonymous said...

Our non-profit is publishing a book on recovery from caffeine addition. We are looking for stories of recovery from various caffeinated products, including coffee, tea, energy drinks, no doz pills, soda, etc. Authors of the stories will be kept completely anonymous. This book is being written to help others who may be suffering from an addiction to caffeine and may identify with someone's story and seek help. Stories are ideally between 2,000 and 4,000 words total. If you or someone you know has struggled with caffeine addiction, this is a great opportunity to reach out and help others. All participants will receive a free copy of the book, once it is published. Please email us at or visit

charlbert said...

nice.... thought half-life is only applicable to radioactive substances... haha..

Jacqueline said...

I really feel bad for those who are addicted to caffeine. I've drank coffee in the past, but I was always more concerned about it staining my teeth.

Jacqueline said...

Pssst. Just hope my English teacher doesn't read my comment. I can hear her now..."I have drunk." :-)