Caffeine is absorbed within 30 to 60 minutes after drinking a cup of coffee and the effect of caffeine lasts from 4 to 6 hours. Pharmacologically, caffeine acts as a central nervous system stimulator, a point that is well made by the coffee ad on TV which calls it “the think drink.” “Caffeine speeds up reaction time and improves automatic processing skills like doing arithmetic problems and proofreading,” says author Stephen Braun “But for more complicated tasks, like complex word problems, caffeine has also been shown to worsen performance.”
John J. Barone, who tracks caffeine consumption at The Coca-Cola Company in Atlanta, reports that the average American adult drinks about 200 mg of caffeine a day, while the top ten percent take in an average of 400 mg/day. The typical American drinks about two cups of coffee a day, although at the peak of caffeine intake in 1962, three cups of coffee a day was typical. Smoking cigarettes removes caffeine from the blood twice as fast as those who do not smoke and this fact may account for why smokers drink more coffee.
The approximate breakdown in terms of the source of caffeine is: coffee-75%, tea-10%, colas-io%, and chocolate-2%. Many persons feel nervous or anxious with as little as 200 mg of caffeine. Since the duration of the effect of the drug is 4 to 6 hours, if one goes to bed at 11 P.M. then the last drink of coffee should be no later than 5 P.M. Caffeine also acts as a constrictor of smooth muscle, which is found in arteries, the bladder, and the colon. It is the arterial vasoconstrictive action which helps with mild migraine (Excedrin, Anacin, BC Powders,Vivacin) and may lead to rebound vasodilatation headache when one withdraws from caffeine too quickly. The smooth muscle effect also acts as a mild stimulant on the bladder, promoting urination and in the colon, a bowel movement. Caffeine can aggravate migraine, anxiety, panic disorder, tremor, cardiac palpitations, gastric reflux, and insomnia.
Caffeine can make you sick if you stop it after taking too much or just by taking too much. Headache patients that I see are commonly confused by the effects of caffeine, thinking it either treats or causes headache. Caffeine can do both but in general I suggest virgin, unadulterated cerebral arteries not getting their daily hit of caffeine.
Caffeine is a drug and after prolonged daily use if caffeine is abruptly stopped or reduced in amount significantly then the patient suffers headache followed by one or more of the following symptoms:
Fatigue, drowsiness, anxiety, depression, nausea, vomiting, clinically significant distress or impairment in social, occupational or other important areas of functioning.
The diagnostic criteria for caffeine intoxication are recent consumption of caffeine in excess of 250 mg a day and the development of five or more the following signs during, or shortly after caffeine use:
Restlessness, nervousness, excitement, insomnia, flushed face, diuresis, gastrointestinal disturbance, muscle twitching, rambling flow of thought and speech, tachycardia or cardiac arrhythmia, periods of inexhaustibility, or psychomotor agitation.
Caffeine may delay sleep onset, which means that it takes a person on caffeine longer to fall asleep. It also may interfere with rapid eye movement (REM) sleep and dreaming. Patients routinely taking caffeine containing medications have more trouble falling asleep at night than those who take no caffeine.
Caffeine helps absorb other drugs in the stomach and is the reason why Excedrin has caffeine and aspirin in it. Caffeine alone may act as a mild pain killer, but together with aspirin, acetaminophen, or ibuprofen may potentiate the analgesic effect. The old pre-triptan era acute migraine treatment, Cafergot, had caffeine and ergotamine in it for the same reason.
Another problem with caffeine is that the companies that sell it don’t put the amount of caffeine on the label so the unwitting consumer doesn’t know how much he is consuming. Americans finally know the amounts of cholesterol, fat, trans fat, and salt in most foods, but the amount of caffeine is still a hidden trade secret. Even caffeinated water—incredible that there is such a thing— doesn’t say how much caffeine is in it. The following table lists the amount of caffeine in some over the counter analgesics, colas, and tea.
Approximate amounts of caffeine in common drinks are:
Coffee, grande 16 oz Starbucks 550
Coffee, tall 12 oz Starbucks 375 Coffee, short 8 oz Starbucks 250 Redline RTD 250
NoDoz, max strength or Vivarin 200
7-Eleven Big Gulp cola 64 oz 190
Coffee non-gourmet 8 oz 135
Coffee instant 8 oz 95
Jolt 2 oz bottle 200
Cola 12 oz 5
Mt. Dew 55
Dr. Pepper 39