Caffeine is a drug that stimulates the central nervous system (CNS). Caffeine is found naturally in coffee, Kola seed kernels or nuts (Cola nidtida), and a variety of teas. Other foods and beverages, such as chocolate and soft drinks, also contain caffeine, and the drug can be purchased in over-the-counter tablet and capsule form (No Doz, Overtime, Pep-Back, Quick-Pep, Caffedrine, and Vivarin). Some prescription pain relievers, medicines for migraine headaches, and antihistamines also contain caffeine.
Caffeine makes people more alert, less drowsy, and improves coordination. It is sometimes included in athletes' diets to improve physical performance. In addition, one recent study found that older people who were given a cup of caffeinated coffee in the morning had fewer late-day memory problems than those who were given decaffeinated coffee. Combined with certain pain relievers or medicines for treating migraine headache, caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract the drowsiness caused by those drugs. Caffeine is also sometimes used to treat other conditions, including breathing problems in newborns and in young babies after surgery.
Kola can be prepared in decoction or tincture form. To prepare a decoction, mix 1-2 tsp of powdered kola nut in a cup of water. After bringing the water to a boil, simmer the decoction on low heat for 10-15 minutes. Tinctures of kola nut can be purchased at many health food stores or mail order suppliers. A tincture is an herbal preparation made by diluting the herb in alcohol, glycerin, or vinegar. Dosage of kola tincture varies by formula and the symptoms or illness it is supposed to treat, but an average recommended dosage might be 1-4 ml three times daily. Powdered kola nut and kola tinctures should be stored in airtight containers away from direct light to maintain potency.
For over-the-counter caffeine preparations, adults and children age 12 years and older should take 100-200 mg no more than every 3-4 hours. In timed-release form, the dose is 200-250 mg once a day. Timed-release forms should not be taken less than 6 hours before bedtime. Caffeine pills or tablets are typically not recommended for children under 12 years of age.
If caffeine is administered in a kola preparation, kola should always be obtained from a reputable source that observes stringent quality control procedures and industry-accepted good manufacturing practices. Consumers should look for the designations "U.S.P." (U.S. Pharmacopeia) or "NF" (National Formulary) on kola nut labeling. Herbal preparations prepared under USP or NF guidelines meet nationally recognized strength, quality, purity, packaging, and labeling standards as recommended by the United States Food and Drug Administration (FDA).
|CAFFEINE CONTENT OF COMMON DIETARY AND MEDICINAL SOURCES|
|Source||Standard amount in milligrams (mg)|
|Bottled beverages (12 oz)|
|Coca Cola Classic||34|
|Coffee (8 oz)|
|Tea (8 oz)|
|Hot cocoa (8 oz)||14|
|Chocolate milk (6 oz)||4|
|Chocolate bar (1 oz)||3–6|
|Medications (per tablet)|
|Midol, Maximum Strength||65|
Avoid taking too much caffeine when it is being taken as an over-the-counter drug. Consider how much caffeine is being taken in from coffee, tea, chocolate, soft drinks, and other foods that contain caffeine. Check with a pharmacist or healthcare professional to find out how much caffeine is safe to use.
People who use large amounts of caffeine over long periods build up a tolerance to it. When that happens, they have to use more and more caffeine to get the same effects. Heavy caffeine use can also lead to dependence. If an individual stops using caffeine abruptly, withdrawal symptoms may occur, including headache, fatigue, drowsiness, yawning, irritability, restlessness, vomiting, or runny nose. These symptoms can go on for as long as a week. In addition, caffeine dependence is not confined to the adult population. A study published in 2002 found that American teenagers have a high rate of caffeine dependence, partly because they consume large amounts of carbonated beverages that contain caffeine.
If taken too close to bedtime, caffeine can interfere with sleep. Even if it does not prevent a person from falling asleep, it may disturb sleep during the night.
The notion that caffeine helps people sober up after drinking too much alcohol is a myth. In fact, using caffeine and alcohol together is not a good idea. The combination can lead to an upset stomach, nausea, and vomiting.
Older people may be more sensitive to caffeine and thus more likely to have certain side effects, such as irritability, nervousness, anxiety, and sleep problems. Recent findings also suggest that people with insulin-dependent diabetes should monitor their caffeine intake. One study published in 2002 found that caffeine appears to decrease insulin sensitivity by about 15%.
Anyone with allergies to foods, dyes, preservatives, or to the compounds aminophylline, dyphylline, oxtriphylline, theobromine, or theophylline should check with a physician before using caffeine. Anyone who has ever had an unusual reaction to caffeine should also check with a physician before using it again.
Caffeine can pass from a pregnant woman's body into the developing fetus. Although there is no evidence that caffeine causes birth defects in people, it does cause such effects in laboratory animals given very large doses (equal to human doses of 12-24 cups of coffee a day). In humans, evidence exists that doses of more than 300 mg of caffeine a day (about the amount of caffeine in 2-3 cups of coffee) may cause miscarriage or problems with the baby's heart rhythm. Women who take more than 300 mg of caffeine a day during pregnancy are also more likely to have babies with low birth weights. Any woman who is pregnant or planning to become pregnant should check with her physician before using caffeine.
Caffeine passes into breast milk and can affect the nursing baby. Nursing babies whose mothers use 600 mg or more of caffeine a day may be irritable and have trouble sleeping. Women who are breast-feeding should check with their physicians before using caffeine.
Other medical conditions
Caffeine may cause problems for people with these medical conditions:
- peptic ulcer
- heart arrhythmias or palpitations
- heart disease or recent heart attack (within a few weeks)
- high blood pressure
- liver disease
- insomnia (trouble sleeping)
- anxiety or panic attacks
- agoraphobia (fear of being in open places)
- premenstrual syndrome (PMS)
At recommended doses, caffeine can cause restlessness, irritability, nervousness, shakiness, headache, light-headedness, sleeplessness, nausea, vomiting, and upset stomach. At higher than recommended doses, caffeine can cause excitement, agitation, anxiety, confusion, a sensation of light flashing before the eyes, unusual sensitivity to touch, unusual sensitivity of other senses, ringing in the ears, frequent urination, muscle twitches or tremors, heart arrhythmias, rapid heartbeat, flushing, and convulsions.
Using caffeine with certain other drugs may interfere with the effects of the drugs or cause unwanted—and possibly serious—side effects. Certain drugs interfere with the breakdown of caffeine in the body. These include oral contraceptives that contain estrogen, the antiarrhythmia drug mexiletine (Mexitil), the ulcer drug cimetidine (Tagamet), and the drug disulfiram (Antabuse), used to treat alcoholism.
Caffeine interferes with drugs that regulate heart rhythm, such as quinidine and propranolol (Inderal). Caffeine may also interfere with the body's absorption of iron.
Serious side effects are possible when caffeine is combined with certain drugs. For example, taking caffeine with the decongestant phenylpropanolamine can raise blood pressure. Very serious heart problems may occur if caffeine and monoamine oxidase inhibitors (MAO) are taken together. These drugs are used to treat Parkinson's disease, depression, and other psychiatric conditions. Consult with a pharmacist or physician about which drugs can interact with caffeine.
Because caffeine stimulates the nervous system, anyone taking other central nervous system stimulants should be careful about using caffeine.
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Bernstein, G. A., M. E. Carroll, P. D. Thuras, et al. "Caffeine Dependence in Teenagers." Drug and Alcohol Dependence 66 (March 2002): 1-6.
Keijzers, G. B., B. E. De Galan, et al. "Caffeine Can Decrease Insulin Sensitivity in Humans." Diabetes Care 25 (February 2002): 399-400.
Maughan, R. "The Athlete's Diet: Nutritional Goals and Dietary Strategies." Proceedings of the Nutrition Society 61 (February 2002): 87-96.
Ryan L., C. Hatfield, and M. Hostetter. "Caffeine Reduces Time-of-Day Effects on Memory Performance in Older Adults." Psychological Science 13 (January 2002): 68-71.
Office of Dietary Supplements. National Institutes of Health. Building 31, Room 1B25, 31 Center Drive, MSC 2086, Bethesda, MD 20892-2086. (301) 435-2920. Fax: (301) 480-1845. http://odp.od.nih.gov/ods/ (Includes on-line access to International Bibliographic Information on Dietary Supplements (IBIDS), a database of published, international scientific literature on dietary supplements and botanicals).
Rebecca J. Frey, PhD