It’s Saturday morning, and you head to your kitchen, turn on your coffee pot, and within a few moments, a wonderful aroma permeates the air. Once the coffee is ready, you take it to your favorite chair and enjoy. This probably sounds like heaven, but do you ever stop to think of the impact the caffeine in your coffee has on you? Could it be bad for your health?

Caffeine is a natural stimulant found in the seeds, nuts, or leaves of 60 different plants. These are then harvested and processed to produce an intensely bitter white powder that provides a distinctive taste and is used to caffeinate foods and beverages. It’s one of the most commonly used ingredients in the world. While it occurs naturally, caffeine can be produced synthetically. Products are required to list caffeine in the ingredients but are not required to list the actual amount.

The scientific name for caffeine is 1,3,7-trimethylxanthine. The word “caffeine” came from the German word kaffee and the French word café, each meaning coffee. However, it predates its current name because the first tea was brewed as far back as 2737 B.C. However, it wasn’t until many years that coffee was reportedly discovered by an Ethiopian shepherd who noticed the extra energy it gave his goats when they ate part of the plant.

By the late 1800s, caffeinated soft drinks came to market, and energy drinks soon followed. Now, 80% of the world’s population consumes a caffeinated product each day, and this number is 90% for adults in North America. Roughly, most people consume about 280 mg of caffeine per day, the equivalent of about two cups of coffee. Most commonly, people get caffeine through coffee, tea, soft drinks, and chocolate. The number of products that contain it continues to grow and includes supplements, medications, gum, and candy.

How it works

The main effect caffeine has on the body is on the central nervous system. Usually, it increases alertness, counteracts tiredness, and improves concentration and focus. Caffeine can do this because it’s quickly absorbed from the gut into the bloodstream. It works in the brain by blocking the effects of adenosine, which is a neurotransmitter that relaxes the brain and makes you feel tired.

Typically, adenosine levels build up over the day, making you increasingly more tired and causing you to want to go to sleep. Caffeine may also increase blood adrenaline levels and increase brain activity of the neurotransmitters dopamine and norepinephrine, which further stimulates the brain and promotes arousal, alertness, and focus. Since it affects your brain, caffeine is often referred to as a psychoactive drug.

Caffeine tends to exert its effects quickly. The amount found in one cup of coffee takes as little as 20 minutes to reach the bloodstream, about 1 hour to reach full effectiveness, and lasts for up to three hours. There’s no accumulation in the body because it’s eventually excreted.

Safe Amount

The U.S. Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) consider an intake of 400 mg of caffeine a day to be safe, which is 2–4 cups of coffee. It’s important to note that fatal overdoses have been reported with single doses of 500 mg. You should limit the amount of caffeine you consume at one time to 200 mg. The Food and Drug Administration (FDA) warns of being cautious with caffeine powders or liquids because it can result in toxic caffeine levels. One teaspoon of powdered caffeine is equivalent to about 28 cups of coffee. According to the American College of Obstetricians and Gynecologists, pregnant women should limit their total daily caffeine intake to 200 mg.

The FDA and the American Medical Association (AMA) classify a “moderate intake” of caffeine daily as “generally recognized as safe.” According to them, the break of the levels are:

• Low = 130 – 200 mg
• Moderate = 200 – 300 mg
• High > 400 mg

To know how much caffeine you’re taking in, it’s essential to know the actual caffeine content in the products you consume. The amounts can vary widely. Besides beverages, caffeine is found in some foods. Milk chocolate (1 ounce) contains 1–15 mg, and dark chocolate (1 ounce) has 5–35 mg. Some prescription or over-the-counter medicines, like cold, allergy, and pain medications, have caffeine too. It’s also a common ingredient in weight loss products. Check out our handy guide that lists the ranges of caffeine in your favorite products.


Many studies have found that moderate caffeine intake can promote a variety of health benefits, including a lower risk of certain cancers, brain conditions, and liver problems. This means that caffeine isn’t as unhealthy as it was once believed. However, some benefits may be caused by substances other than caffeine because coffee and tea contain other bioactive compounds that may also be beneficial.

One of the obvious advantages of caffeine that millions of people rely on daily is to stay alert and improve concentration. One review showed that after participants ingested 37.5–450 mg of caffeine, they had improved alertness, short-term recall, and reaction time. Since it stimulates the central nervous system, caffeine is thought to increase metabolism by up to 11% and fat burning by up to 13%. This means that consuming caffeine may slightly increase the number of calories you burn in a day.

When it comes to exercise, caffeine may increase the use of fat as fuel, which can help the glucose stored in muscles last longer, potentially delaying the time it takes your muscles to reach exhaustion. Caffeine may also enhance muscle contractions and increase tolerance to fatigue. One study found that when consumed 1 hour before exercise, caffeine elevated endurance performance by up to 5%. The amount consumed was 2.3 mg per pound (5 mg per kg) of body weight, but quantities as low as 1.4 mg per pound (3 mg per kg) may be sufficient to reap the gains. Caffeine is also thought to reduce perceived exertion during exercise by up to 5.6%, making workouts feel easier.

Caffeine has a positive impact on your mental health too. One study linked drinking 2–3 cups of caffeinated coffee (providing about 200–300 mg caffeine) per day to a 45% lower risk of suicide. Another study states there’s a 13% lower risk of depression in caffeine consumers. Evidence indicates that drinking between 3–5 cups of coffee per day or more than 3 cups of tea per day may reduce the risk of brain diseases, like Alzheimer’s and Parkinson’s, by 28–60%. An observational study in The Journals of Gerontology: Series A found that adults 65 and older who consume an average of 261 mg of caffeine a day for ten years reported fewer dementia symptoms than those who consumed an average of 64 mg daily.

Despite what you may have heard, caffeine might lower the risk of heart disease. Data shows that if you drink between 1 – 4 cups of coffee a day, you might have a 16–18% lower heart disease risk. Other studies indicate that drinking 2–4 cups of coffee or green tea per day is linked to a 14–20% lower risk of stroke. For some people, caffeine may slightly raise blood pressure, but this effect is small and tends to fade when they consume caffeine regularly. Also, studies have shown that coffee and tea aren’t associated with increases in blood pressure or arrhythmias; however, soft drinks are. Research additionally revealed that decaffeinated coffee and tea didn’t provide the same benefits as the caffeinated versions.

Drinking coffee is associated with a 29% lower risk of developing type 2 diabetes, and decaffeinated coffee was linked to a 21% lower risk. Caffeine may decrease the risk of premature death by as much as 30%, especially for women and people with diabetes. When it comes to your liver, coffee may reduce the risk of liver damage (cirrhosis) by as much as 84%. You can reduce liver cancer risk by up to 64% and colorectal cancer risk by up to 38% by consuming 2 – 4 cups daily. Drinking 3 cups of coffee a day for as little as three weeks may increase the amount and activity of beneficial gut bacteria. Four or more cups per day may lower skin cancer risk by 20% and reduce the risk of gout by 40% in men and 57% in women.

A 2015 study found that regular caffeine intake may improve erectile dysfunction (E.D.). Researchers looked at daily caffeine intake and rates of E.D. in men who were part of the National Health and Nutrition Examination Survey. It demonstrated that those who consumed daily caffeine equal to two to three cups of coffee were 42% less likely to report E.D.

Caffeine has been considered a diuretic for years. Every day your body needs water to be able to function correctly. You lose water through respiration, skin, renal, and gastrointestinal tract. Your intake of water comes from liquids and foods. Many factors, like age, activity level, health, diet, and environment, affect your water balance. Research has shown that caffeine intake impacts your fluid balance. One study had 12 caffeine consumers abstain from caffeine for five days and then were given 642 mg of caffeine in the form of coffee. Their urine output increased when given caffeine.

A different study tested the effect of 45 mg, 90 mg, 180 mg, or 360 mg of caffeine on urine volume in eight men. An increase was seen only at the 360 mg dose of caffeine. The studies didn’t evaluate the impact of caffeine when consumed regularly. This is an important consideration because a one-time amount may affect the body differently than daily consumption. Subsequent studies have shown that caffeine-containing beverages didn’t alter urinary output any differently. Your reaction most likely depends on the amount you consume, the type of product, and your tolerance level.


Caffeine consumption, while considered safe, can be habit-forming. Psychiatric conditions are categorized by a manual published by the American Psychiatric Association (APA) called the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). It covers all mental health disorders for both children and adults. The manual doesn’t classify substances as addictive but instead sets the criteria for substance dependence.

The standards includes tolerance, substance-specific withdrawal syndrome, substances often taken in larger amounts or over a longer period than expected, persistent desire or unsuccessful efforts to cut down or control use, a great deal of time spent in activities necessary to obtain/use/recover from the effects of the substance, giving up important social/occupational/recreational activities, and continued use despite knowing it causing a persistent or recurrent physical or psychological problem. To be considered dependent upon a substance, the user needs to meet at least three of the above criteria. So, it’s possible to be addicted to caffeine if you meet the requirements.

When it comes to caffeine intoxication, the DSM-IV lists it as a clinical syndrome. It’s described as a recent caffeine intake and five or more symptoms that develop during or shortly after. These symptoms include restlessness, nervousness, excitement, insomnia, flushed face, diuresis, and gastrointestinal complaints. If you don’t consume caffeine regularly, you have a higher risk of developing these. However, they can occur in anyone who consumes more caffeine than what their body is used to or can handle.

One area of particular concern is energy drinks. The amount of caffeine in energy drinks can vary widely, but it’s typically high. In addition, they often contain sugars, vitamins, herbs, and supplements. Some research has shown that energy drinks can be dangerous for your cardiovascular system. A small study published in 2017 in the Journal of the American Medical Association (JAMA) discovered that healthy people who consumed a 32-ounce energy drink with 320 mg of caffeine and 108 grams of sugar were more likely to have an abnormal electrocardiogram (ECG) after two hours and mildly elevated blood pressure after six hours.

Another worry with caffeine is that high intake may accelerate bone loss. One study demonstrated that elderly postmenopausal women who consumed more than 300 mg per day of caffeine lost more bone in their spine than women who had less. Experts say that coffee and tea drinkers may offset this by adding milk to their beverages. Further study is needed to make a definitive decision about the role of caffeine and osteoporosis.

Caffeine intake, especially in the afternoon, can interfere with your sleep. If you have even a small amount of sleep loss, it can add up. It disrupts your daytime alertness and performance. So, you consume caffeine to fix this, which creates a vicious cycle.

Caffeine is known to interact with some medications and supplements. It increases the effects of Zanaflex (muscle relaxant) and Luvox (antidepressant). Ephedrine, a common ingredient in decongestants, mixed with caffeine, can increase your risk of high blood pressure, heart attack, stroke, or seizure. You’ve probably heard of taking echinacea (an herbal supplement) to prevent colds or other infections. It’s vital to know that it may increase caffeine concentration in your blood and may increase caffeine’s unpleasant effects.

Caffeine can easily cross the placenta, increasing the risk of miscarriage or low birth weight. Therefore, pregnant women should limit their intake. A small amount of caffeine is passed through breast milk, so you should check with your doctor before consuming caffeine while breastfeeding.

When it comes to children and adolescents, caffeine should be avoided as much as possible. It definitely shouldn’t be given to children under 12. Those who are older should consume amounts less than recommended for an adult. This is because children are more sensitive to caffeine’s effects, and its impact on the developing brain isn’t known. Some psychologists are concerned that a pattern of caffeine use or abuse as a child or teen may lead to subsequent drug and alcohol use or abuse as an adult.

Caffeine Sensitivity & Withdrawal

How you react to caffeine depends on your sensitivity, how regularly you consume it, and how quickly your body digests it. Some common side effects of excessive caffeine intake include anxiety, restlessness, tremors, irregular heartbeat, trouble sleeping, headaches, migraine, and high blood pressure. It’s possible that your body can adjust to how it reacts to caffeine the more you consume. Caffeine can metabolize at different rates among individuals for various reasons. One example is cigarette smokers metabolize caffeine twice as fast as nonsmokers.

Since some people become physically dependent on caffeine, the absence or reduction of it could result in caffeine withdrawal. The onset of withdrawal symptoms typically begins 12-24 hours after last consumption, with the peak intensity occurring at 20-51 hours. However, they can last for two to nine days. It’s easy to see why people have a hard time cutting it out of their diet. If you’re drinking more than 4 cups of coffee, multiple energy drinks, or large quantities of other caffeinated products in a day, you might need to cut back. Your goal should be to consume no more than 400 mg per day.

How can you change your habit?

There are several things you can do to change your caffeine habit. The most important is to start paying attention to how much caffeine you’re actually ingesting each day. The first step is to read labels carefully. Keep in mind some foods or drinks that contain caffeine don’t list it.

Once you know where your caffeine is coming from, cut back gradually. This can mean drinking one fewer can of soda, drinking a smaller cup of coffee, switching to decaffeinated products (have less caffeine but not necessarily none), or avoiding consuming caffeine late in the day.

If you’re a tea drinker, brew it for less time because this cuts down on its caffeine content. You can also try herbal teas that don’t have caffeine. Make sure you read the labels on medications because some over-the-counter pain relievers contain caffeine.

Regarding decaf coffee, one study published by the Journal of Analytical Toxicology found that nine out of 10 tested cups of decaf coffee from shops and restaurants contained 8.6 – 13.9 mg of caffeine, and decaffeinated espresso shots contained 3 – 16 mg of caffeine per shot. Depending on your intake, you can end up consuming more caffeine from decaffeinated drinks than you would in one cup of regular coffee.

Caffeine isn’t bad for you. It all comes down to how much you consume and the frequency of that consumption. As with most things, moderation is key. By being aware of your intake and how you feel after, you’ll know just much caffeine is the right amount for you!