Caffeine is the most commonly used drug in the world. It is a naturally occurring substance found in coffee, tea, chocolate, and certain other plants; it is also frequently added to other products such as soda, energy drinks, over-the-counter cold medications, and weight-loss aids. Although consumption of small to moderate doses of caffeine is thought to be safe, some users become dependent on it and are unable to cut back despite problems caused by their intake.
While not technically a diagnosable condition, caffeine-related disorder, or caffeine-use disorder, is listed in the DSM-5 as a condition that warrants further study because the stimulating effects and side effects of caffeine can mimic those of recreational drugs. Some people, particularly adolescents, are known to use and abuse caffeinated products such as energy drinks and to combine caffeine and alcohol for a more potent effect. Caffeine-related disorders include caffeine intoxication and caffeine withdrawal.
Caffeine functions as a central nervous system stimulant and also a diuretic. As a stimulant, caffeine can cause the heart to beat faster and hasten the effects of cold temperatures on the body. Contrary to common myth, coffee will not sober up an inebriated person; instead, it typically causes agitation. Similarly, caffeine should never be given to a frostbite or hypothermia victim.
Once ingested, caffeine is absorbed and distributed quickly. After absorption, it passes into the brain. Caffeine does not accumulate in the bloodstream nor is it stored in the body. It is excreted in the urine hours after it has been consumed.
The effects of caffeine on health have been widely studied—in particular, its effects on fibrocystic breast disease, conditions of the heart and blood vessels, birth defects, reproductive function, and behavior in children. The American Medical Association Council on Scientific Affairs concludes, "Moderate tea or coffee drinkers probably have no concern for their health relative to their caffeine consumption provided other lifestyle habits (diet, alcohol consumption) are moderate as well."
Overuse can lead to what is called "caffeine intoxication," which involves restlessness, nervousness, excitement, flushed facial skin, insomnia, increased urine production, gastrointestinal upset, irregular heartbeat, muscle twitching, jumpiness, or shakiness, or any combination of these symptoms. Since caffeine affects different people in different ways, the definition of "overuse" can vary.
Although some research suggests that regular use of caffeine is more of a habit than an addiction, the fact that overuse causes physical and psychological symptoms and that withdrawal symptoms develop when people stop drinking caffeinated beverages indicates the substance has addictive qualities.
Symptoms of caffeine withdrawal can include:
- Significant fatigue or drowsiness
- Depressed mood
- Difficulty concentrating
- Flu-like symptoms such as nausea and muscle pain
Withdrawal symptoms typically begin 12 to 24 hours after the last caffeine dose, peak after one to two days of abstinence, and may last up to nine days.
Light to moderate caffeine consumption does not generally lead to worrisome symptoms and, in fact, may provide some health benefits, including reduced risk of heart disease and stroke, treatment of migraine headaches, increased alertness and mental acuity, fewer symptoms of depression, and even reduced risk of dementia. For some people, these potential benefits may outweigh any risks or negative side effects associated with caffeine use.
Caffeine is defined as a drug because it is a central nervous system stimulant. Regular use of caffeine may cause a mild physical dependence.
There is no dietary requirement for caffeine. About 250 to 300 milligrams of caffeine per day is considered a moderate amount, roughly equivalent to three cups of coffee. Consuming more than 10 8-ounce cups per day is considered excessive, and caffeine poisoning can occur from such amounts.
Since caffeine-related disorder is not recognized as a diagnosable condition, there is no standardized treatment. It is on the list of substance-related disorders that require more investigation because progressive caffeine overuse that results in dependency could lead to negative physical, psychological, and social consequences. In case of a caffeine overdose, individuals should call local poison control to assess whether hospitalization is necessary.
Pregnant women and people with coronary heart disease or peptic ulcers may be advised by their health care provider to restrict or avoid using caffeine.
Many drugs interact with caffeine. Patients should consult a health care provider or pharmacist about potential interactions when taking medications.
People with these conditions or circumstances should avoid or limit caffeine:
• Irregular heartbeats, arrhythmias, caffeine may increase frequency
• Acid reflux, caffeine can loosen the lower esophagus
• Epilepsy, caffeine may increase seizure frequency
• Anxiety, caffeine may increase feelings of panic
• Insomnia and other sleep difficulties
• Children and pregnant women
It is generally recommended that children avoid caffeine use. If a child does use caffeine, consumption should be closely monitored. Caffeinated beverages may be replacing nutrient-dense foods such as dairy, and consumption may interfere with the absorption of certain nutrients such as calcium and iron. A child may also eat less after drinking caffeine because it acts as an appetite suppressant.