You can call it 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6,-dione OR 1,3,7-trimethylxanthine, but what we are really talking about is CAFFEINE. Caffeine may be the most popular drug in the world. We consume caffeine in coffee, tea, cocoa, chocolate, some soft drinks, and some drugs. The actual source of caffeine is the coffee bean, tea leaf, kola nut and cacao pod. Pure caffeine is odorless and has a bitter taste. coffee

Effects of Caffeine on the Nervous System

Caffeine is a central nervous system stimulant. In moderate doses, caffeine can:
  • increase alertness
  • reduce fine motor coordination
  • cause insomnia
  • cause headaches, nervousness and dizziness

In massive doses, caffeine is lethal. A fatal dose of caffeine has been calculated to be more than 10 grams (about 170 mg/kg body weight) - this is the same as drinking 80 to 100 cups of coffee in rapid succession - not an easy thing to do.

Caffeine enters the bloodstream through the stomach and small intestine and can have its effects as soon as 15 minutes after it is consumed. Once in the body, caffeine will stay around for hours: it takes about 6 hours for one half of the caffeine to be eliminated.

Caffeine belongs to the xanthine chemical group. Adenosine is a naturally occurring xanthine in the brain that is used as a neurotransmitter at some synapses. One effect of caffeine is to interfere with adenosine at multiple sites in the brain including the reticular formation. Caffeine also acts at other sites in the body to increase heart rate, constrict blood vessels, relax air passages to improve breathing and allow some muscles to contract more easily.

Some studies show that caffeine causes physical dependence. One way to tell if someone "needs" that cup of coffee or bottle of Coke is to take it away from them and then see if they have any withdrawal symptoms. Typical withdrawal symptoms associated with caffeine are headache, fatigue and muscle pain. These symptoms can occur within 24 hours after the last dose of caffeine. One study has stated that the minimum consumption of caffeine for physical dependence is 4 cups of coffee per day. Other studies say that a few more cups of coffee are needed to develop dependence.

Hear IT!
Adenosine Caffeine Stimulant

Caffeine can be found in many drinks, food and drugs. The following items all contain various amounts of caffeine:

ItemItem SizeCaffeine Content (mg)
Coffee150 ml (5 oz)60-150

Coffee, decaf150 ml (5 oz)2-5
Tea150 ml (5 oz)40-80
Hot Cocoa150 ml (5 oz)1-8
Chocolate Milk225 ml2-7
Jolt Cola12 oz100
Josta12 oz58
Mountain Dew12 oz55
Surge12 oz51
Tab12 oz47
Diet Coca Cola12 oz45
Coca Cola12 oz64
Coca Cola Classic12 oz23
Tab12 oz46
RC Cola12 oz34
Dr. Pepper12 oz61
Mello Yellow12 oz35
Mr. Pibb12 oz27
Pepsi Cola12 oz43
Cherry Coca-Cola8 oz23
Surge8 oz35
7-Up12 oz0
Mug Root Beer12 oz0
Sprite12 oz0
Did you know?

An American tea and coffee merchant named Thomas Sullivan invented the tea bag in 1904. He used the tea bag to send samples to his customers.

ItemItem SizeCaffeine Content (mg)
Ben/Jerry No Fat Coffee
Fudge Froz. Yog.
1 cup85

Starbucks Coffee Ice Cream1 cup40-60
Dannon Coffee Yogurt8 oz.45
Chocolate Bar50 g3-63
Chunky Bar1 bar (40 g)11.6
100 Grand Bar1 bar (43 g)11.2
Nestle Crunch Bar1 bar (40 g)10
Krackel Bar1 bar (47 g)8.5
Peanut Butter Cup1 pk (51 g)5.6
Kit Kat Bar1 bar (46 g)5
Mr. Goodbar1 bar (50 g)5
Raisinets10 pieces (10 g)2.5
Butterfinger Bar1 bar (61 g)2.4
Baby Ruth Bar1 bar (60 g)2.4
Special Dark Sweet Chocolate Bar1 bar (41 g)31
Chocolate Brownie1.25 oz8
Chocolate Chip Cookie30 g3-5
Chocolate Ice Cream50 g2-5
Milk Chocolate1 oz1-15
Bittersweet Chocolate1 oz5-35
Butterfinger Bar1 bar (2.16 oz)2
After Eight Mint2 pc (8 g)1.6
Jell-O Pudding Pop
1 bar (77 g)2

Non-prescription Drugs
Item (1 tablet or capsule)Caffeine Content(mg)
No Doz100

Sources: Pennington, J.A.T., Food Values of Portions Commonly Used (18th Edition), J.B. Lippincott, Philadelphia, 2005; Soft Drink Manufacturers Association; United States Department of Agriculture, Human Nutrition Information Service, Handbook #8-14 (1986) and Handbook #8-19 (1991); Starbuck Co. Information Pamphlet, American Beverage Association

Researchers have attempted to find out how much caffeine people consume every day. Americans consume about 45 MILLION pounds of caffeine each year. In the United States, coffee drinkers drink an average of 2.6 cups per day. Total caffeine intake for coffee drinkers was 363.5 mg per day - this includes caffeine from coffee AND other sources like soft drinks, food and drugs. Non-coffee drinkers even get plenty of caffeine: former coffee drinkers get about 107 mg per day and people who have never had coffee get about 91 mg per day. (References for these numbers is Schreiber et al., Measurement of coffee and caffeine intake: Implications for epidemiolgic research, Preventive Medicine, 17:280-294, 1988 and Chou, T., Wake up and smell the coffee. Caffeine, coffee and the medical consequences, West. J. Med., 157:544-553, 1992)

One more thing to think about...Caffeine does NOT counteract the effects of alcohol. In other words, coffee does NOT make a drunk person sober or fit to drive.

Try it!

How much caffeine do you consume each day? Use this worksheet to keep track of the products with caffeine that you consume. Write down the name of the product, the amount you consume of each product (for example, the number of ounces, grams, cups, bars, pills), the amount of caffeine in each product and the time that you consumed the product. Use separate worksheets if you want to track your caffeine consumption on different days.

Did you know?

  • The United States imports about 30% of the world's coffee. (Statistic from Prevention's Giant Book of Health Facts, 1991.)
  • Worldwide, 120,000 tons of caffeine are consumed each year.
  • In the US, more than 80% of adults consume caffeine on a daily basis.
  • The average daily consumption of caffeine among adults is 200 mg/day.
  • Women metabolize caffeine about 25% faster than men.
(Reference for the last four facts: The World of Caffeine. The Science and Culture of the World's Most Popular Drug by B.A. Weinberg and B.K. Bealer, New York: Routledge, 2001.)

(Reference for data in graph: Fredholm, B. et al., Actions of caffeine in the brain with special reference to factors that contribute to its widespread use, Pharmacological Reviews, 51:83-133, 1999.)

Did you know?

Caffeine was on the International Olympic Committee (IOC) list of prohibited substances for many years. Athletes who tested positive for more than 12 micrograms of caffeine per milliliter of urine could be banned from the Olympic Games. This level can be reached after drinking about 5 cups of coffee. However, the IOC REMOVED caffeine from the banned list in 2004. Caffeine was taken off of the list of banned substances so that athletes who drink cola or coffee are not penalized. (References: World Anti-Doping Agency.)

They said it!

"Coffee and tea are extremely hurtful to persons who have weak nerves."
--- John Wesley, 1747 (in The Iliac Passion)

For more information about caffeine, see:
  1. Does Drinking Coffee Prevent Parkinson's Disease? - from Neuroscience for Kids
  2. Caffeine - "How Stuff Works"
  3. Caffeine Content Chart
  4. Pendergrast, M., Uncommon Grounds. The History of Coffee and How it Transformed Our World, New York: Basic Books, 1999.



GO TO: Alcohol Amphetamines Caffeine Cocaine
Heroin Inhalants LSD Marijuana
Nicotine Ecstasy Rohypnol 1,4-Butanediol
GHB Barbiturates PCP Hallucinogenic Mushrooms

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