Is Caffeine Addictive? Can It Be Harmful"?
Yes. Yes.
Our original premise was that as Americans we do not understand the nation’s drug problem. Perhaps all of us will identify schedule 1 narcotics, street drugs, as part of the problem. Most of us would know that schedule 2 narcotics, prescription pharmaceuticals, are abused. Fewer but still many would include alcohol. We were very strong in suggesting that nicotine is a very serious addictive drug in America causing the death of more Americans than alcohol and schedule 1 and schedule 2 narcotics combined. What of caffeine?
Caffeine is the most widely used, addictive substance in the world. 90% of Americans use caffeine usually in the form of coffee, tea, soft drinks or energy drinks. This use as a percent of Americans far outpaces alcohol at 70%, cannabis at 16%, nicotine at 14%, and other schedule 1 narcotics at 7%. Like alcohol, its prevalence makes its ill effects more damaging than might be suggested on an individual basis. A lower percentage may abuse the drug or become addicted but since there are so many users the national damage is more pronounced.
A thorough review of the addictive nature of caffeine was included in a 2013 article in the Journal of Caffeine Research, “Caffeine Use Disorder: A Comprehensive Review and Research Agenda”. Among those Americans using caffeine, average consumption exceeds 200 mg of caffeine per day which is more than is contained in two 6-ounce cups of coffee or five 12-ounce cans of soft drinks. Consumption of low to moderate doses of caffeine is generally safe and the human body will metabolize the drug with little, harmful effect. However, several clinical studies show that some caffeine users become dependent on the drug and are unable to reduce consumption despite knowledge of recurrent health problems associated with continued use.
Caffeine results in dependence or addiction in the same way as other drugs such as cocaine and amphetamines and in some cases like other drugs we have been discussing including nicotine, narcotics and alcohol. Caffeine stimulates dopamine activity by removing the negative regulating effects of dopamine receptors. This dopamine release in the brain is also the pharmacologic effect of those other drugs.
Like those other drugs, the dependency and addiction for caffeine have similar mechanisms. One is that we tend to “like” the drug and associate this with taste. That may be true to some extent but that appreciation of taste is in great measure an association subjective effect including a sense of increased well-being, energy, alertness, and sociability. Essentially, as we may recall from our undergraduate psychology course, the taste effect is to a greater and lesser extent conditioning.
Similar to those other addictive drugs tolerance effects occur with caffeine. This occurs when the physiological, behavioral, and subjective effects of caffeine decrease after repeated exposure such that the same dose of caffeine no longer produces equivalent effects and a higher dose is needed. Tolerance has been reliably demonstrated in humans. Tolerance effects do not occur for most users and at lower, even repeated dosages.
Another indication of dependence or addiction is withdrawal. Anyone who starts their day with caffeine knows that when they are deprived of the drug they experience headache, fatigue, difficulty concentrating, and moodiness. They know, too, that low doses of caffeine suppress these symptoms. These are not localized phenomena and have been well documented in humans.
In sum, caffeine often causes dependence and sometimes addiction. The severity of that dependence/addiction depends on how individuals metabolize the drug. Those who process the drug more quickly will feel the effects less. This is in some part the genetic nature of all addiction and certainly with caffeine.
The World Health Organization and some health care professionals recognize caffeine dependence as a clinical disorder. WHO maintains the International Statistical Classification of Diseases and Health Problems current version 11. The ICD 11 codes are used globally to define and sometimes reimburse treatment for recognized diseases. ICD 10 recognized Caffeine Dependence Disorder as a behavioral, cognitive, and physiological phenomenon that develops after repeated substance use, includes a strong desire to take the drug, difficulties in controlling use, persisting in use despite harmful consequences, a higher priority given to drug use than to other activities and obligations, increased tolerance, and often physical withdrawal state.
The American Psychiatric Association maintains the Diagnostic and Statistical Manual of Mental Disorders now in the fifth edition. The DSM-V combines what were previously defined by drug (alcohol, nicotine, amphetamines, etc.) into Substance Use Disorder which includes symptoms of abuse and addiction. Psychiatry notes that the DSM-V diagnoses includes Caffeine Intoxication, Caffeine Withdrawal, Caffeine Use Disorder, Caffeine-Induced Anxiety Disorder, and Caffeine-Induced Sleep Disorder. The DSM-5 diagnosis of Caffeine Use Disorder includes symptoms that can also contribute to a diagnosis of caffeine intoxication and caffeine withdrawal, Caffeine use disorders are a pattern of compulsive caffeine use, leading to significant distress or impairment in social, occupational, or other areas of functioning.
It is yet early in the clinical study of Caffeine Use Disorder and as a result the prevalence of dependence and addiction to caffeine is not easily defined. There are early studies that attempt to measure dependence on the four DSM criteria -- desire to cut down, use despite harm, withdrawal, and tolerance. The most common report is that 9-10% of the measured display at least three of these four criteria. Some studies showed dependence as high as 30% which seems unusually high and suggests a wide variation of measuring these effects. While this 9-10% may still seem like a high number to some, this may suggest that including milder forms of use such as mild withdrawal account for that number.
There are studies that demonstrate a greater dependence in more at risk populations such as individuals with eating disorders, other psychiatric disorders, and individuals with a recent history of licit or illicit drug use. The prevalence of Caffeine Use Disorder and the rates of endorsement of each diagnostic criterion were typically higher among participants in these studies. Some studies suggest a 16% dependence rate for eating disorders and psychiatric conditions and as high as 35% for people with recent, other drug abuse. Anyone who has attended a meeting of AA or NA might endorse that higher number.
As to adverse effects, the severity will depend both on dose and how the individual metabolizes the drug. As reported in a 2025 article on StatsPearl, mild adverse effects include anxiety, restlessness, fidgeting, insomnia, facial flushing, increased urination, irritability, muscle twitches or tremors, agitation, arrythmia, and gastrointestinal irritation.
Severe adverse effects may include disorientation, hallucinations, psychosis, seizures, and cardiac arrhythmias. Caffeine can lead to withdrawal symptoms if habitual users abruptly cease consumption. These symptoms typically begin 12 to 24 hours after the last intake, peak in 1 to 2 days, and may last up to 1 week.
There is also the risk of drug to drug interaction. Specifically, caffeine can interact with various psychiatric medications, including antidepressants, antipsychotics, anxiolytics, and sedatives. Seizures do occur with certain of these drug interactions with caffeine. The sedative effects of alcohol and the psychoactive stimulant effects of caffeine can mask their respective influences on both sleep quantity and sleep quality.
There is some indication of contraindications to caffeine use and caution is necessary with certain medical conditions. Those include:
Hypersensitivity
Severe anxiety
Cardiovascular disease or symptomatic cardiac arrhythmias
Peptic ulcer or gastroesophageal reflux disease
Liver impairment
Renal impairment
Seizures, and
Pregnancy
There are rare but very concerning instances of caffeine toxicity or overdose with rare fatalities. These may occur in people with the contraindications listed above. This is especially important for those beverages with added caffeine. Additive caffeine does not necessarily require FDA approval. A typical dose of caffeine in coffee, tea or soft drink may be 70 to 100 mg, and doses up to 400 mg/d are deemed safe. A toxic dose of caffeine w adverse effects such as tachycardia, arrhythmia, altered mental state, and seizures may occur, is estimated to be around 1.2 g and the estimates of a life-threatening dose of caffeine range from 10 to 14 g.
As 90% of the audience has used caffeine already today, we are reminded of Mencken’s definition of Puritans. That is not our intent, and we consume coffee as regularly as the next person. It is our intent to again expand the national dialogue about substance use, abuse and addiction. It would appear that caffeine use is less addictive across the populace compared with other drugs including alcohol, and that the negative effects are less common than other drugs. Certainly, the national association of caffeine with the start of day is, in itself, not problematic. That does not mean, though, that we should ignore the negative consequences that are present and the 9-10% of users who are predicted to develop more problematic dependence.
Gene Gilchrist
Louisville, Kentucky
