Caffeine side effects, risk and health benefits, withdrawal and addiction
August 10 2017 by Ray Sahelian, M.D.

The most popular drug in the United States is caffeine. Around 80% of Americans drink or eat something that contains caffeine every day. It's in everything from coffee to sodas to bottled iced tea to chocolate. Many people consume it in order to feel more alert. Some use it for weight loss.

Caffeine side effects, negative reactions
Excessive caffeine intake can lead to unpleasant, negative caffeine effects including fast heart rate, palpitations, diuresis (excessive urination), nausea and vomiting, restlessness, anxiety, depression, tremors, and insomnia or shallow sleep. Consumption may also cause ringing in the ears or tinnitus. Anxiety from caffeine is a common occurrence.

Interactions with supplements
Q. With regard to minimising any interaction with caffeine (coffee and tea), how long before and after the consumption of a caffeinated beverage is it safe to take turmeric drinks or supplements?
   A. Turmeric is a safe supplement and should not interfere with the timing of caffeine ingestion.

Where is caffeine found?
Caffeine is a xanthine alkaloid found in the leaves and beans of the coffee tree, in tea including green tea, yerba mate, guarana berries, and in small quantities in cocoa, the kola nut and the Yaupon holly. In plants, caffeine acts as a natural pesticide that paralyzes and kills many insects feeding upon them. One common source of caffeine is the coffee plant, the beans of which are used to make coffee. Caffeine content varies substantially between Arabica and Robusta species and to a lesser degree between varieties of each species.

Effects on the body
Caffeine is the most widely used pharmacologic substance in the world. It is found in common nonessential grocery items (e.g., coffee, tea, cocoa, and chocolate). Caffeine is a central nervous system stimulant, having the effect of warding off drowsiness and restoring alertness. Caffeine-containing beverages, such as coffee and tea, enjoy great popularity, making caffeine the world's most popular psychoactive substance and a concern for caffeine addiction and caffeine withdrawal.
   Caffeine is a central nervous system stimulant, has mild bronchial tube dilating potential, is a mild vasoconstrictor, and has mild diuretic and anorexic effects. Caffeine acts as a potent antagonist of central and peripheral nervous system adenosine receptors. If you would like to feel a nice alertness as an alternative, try CDP Choline pills.
   Caffeine has a stronger disruptive effect on daytime, catch-up sleep after a night of sleep deprivation than it does on a normal night's sleep. Consuming caffeine at night is known to make it more difficult to fall asleep and to worsen sleep quality.

Blood pressure
Drinking three or more cups of caffeinated espresso per day increases blood pressure and blood glucose.

Blood sugar
Reducing caffeine consumption could help patients with diabetes better control their blood sugar levels. Giving caffeine to those with type 2 diabetes causes their levels of the blood sugar (glucose) to rise throughout the day, especially after meals.

Caffeine and blood vessels
The effects of caffeine on cardiovascular diseases, including hypertension, remain controversial, and there is little information on its direct effect on vascular function. Caffeine increases systolic and diastolic blood pressures. Acute administration of caffeine augments endothelium-dependent vasodilation in healthy young men through an increase in nitric oxide production.

Colon cancer patients who regularly drink caffeinated coffee may be lowering their risk of tumor recurrence and death from the disease,

Exercise and athletes
Many competitive athletes think that taking caffeine pills or drinking coffee gives them an edge. Studies do not show caffeine to be an effective help for athletes. The placebo effect is more likely an explanation why some athlete's think caffeine helps their performance.

Hair growth
What's your opinion on caffeine based shampoos like Alpecin and others? How much difference in slowing down hair loss do you think they make?
   A. This is an area I am not familiar with.

Caffeine and headache
When used occasionally, caffeine has a mild analgesic effect for headache treatment or may help the actions of other pain medications. Chronic repetitive exposures to caffeine increase the risks for development of analgesic-overuse headache, chronic daily headache, and physical dependency. Stopping the use of caffeine use after chronic exposures leads to a withdrawal syndrome with headache as a dominant symptom.

Pregnant women who consume more than 200 milligrams of caffeine a day, equivalent to about two cups of coffee, have twice the risk of miscarriage as women who consume no caffeine at all.

Caffeine during pregnancy
Sons born to women who drink the equivalent of three cups of coffee a day during pregnancy are more likely to have undescended testes.
In 1980 the Food and Drug Administration issued a warning to avoid caffeine during pregnancy. Since then, the question of having caffeine or not having caffeine has been on the minds of many pregnant women. There have been studies that have linked caffeine to miscarriages, low birth weight, Sudden Infant Death Syndrome, heartbeat abnormalities, and other effects. At this time it is best to limit caffeine intake during pregnancy.

Sleep, insomnia
Caffeine does more than serve as an eye-opener: When consumed a few hours before bed, the most widely consumed psychoactive drug in the world seems to disrupt the body's internal clock. And this could cause jet lag-style sluggishness during daylight hours.

Use of caffeine in dietary supplements
Caffeine is added to certain dietary supplements to increase energy and alertness. In my opinion, caffeine is not a good energy enhancer. Caffeine is also added to certain dietary supplements to compliment headache relief products and as an addition to weight loss supplements.

Caffeine Content in Coffee and Caffeine Pill
One 'shot' of coffee contains about 40 mg of caffeine. Thus, a "double shot" espresso contains about 80 mg. A single serving (6 fl oz / 150 ml) of strong drip coffee would deliver about 100 mg. However, there is a large variation in the amount of caffeine per serving, ranging from about 40 mg to 120 mg. Caffeine pills made by various companies contain caffeine in varying doses ranging from 40mg to 150 mg.

Caffeine Content in different beverages.

Brewed Coffee (6oz.) 80 to 120mg
Instant Coffee (6 oz.) 40 to 60mg
Decaffeinated Coffee 3 to 5 mg
Cola (12 oz.) 40 to 50 mg
Black Tea (6oz.) 30 to 40mg
Cocoa (6 oz.) 6 to 10 mg
Decaffeinated Black Tea (6oz.) 3 to 5mg
Green Tea (6oz.) 20 to 40 mg
Decaffeinated Green Tea (6oz.) 2mg

Caffeine Content in Decaf Coffee
Decaf coffee is not caffeine free. Most often it has about a fifth to a tenth of the amount of caffeine in regular coffee. Instant decaffeinated Folgers Coffee Crystals does not have any caffeine, but decaf coffee from many coffee shops, including major chains such as Starbucks, contained caffeine averaging about 1 mg of caffeine per ounce of decaf coffee. In some people who are sensitive to caffeine and drink several cups a day, even moderate caffeine levels can increase heart rate, blood pressure, agitation and anxiety.

Caffeine content in chocolate
Hershey's Special Dark Chocolate Bar 1 bar (1.5 ounces) has 30 mg of caffeine, Hershey Bar (milk chocolate) 1 bar (1.5 ounces) has 10 mg, cocoa or hot chocolate has 5 mg in 8 ounces.

Green tea caffeine
Caffeine is consumed from a variety of sources including coffee, tea, cola, and cocoa. Many medications also contain caffeine. In the case of tea, both the type of tea and brewing time affect caffeine content. A typical cup of green tea contains less than a cup of regular black tea. Two cups of tea provide less than half the US average daily consumption of caffeine (200 mg). Those who are sensitive to caffeine should limit their tea drinking to decaffeinated varieties.

Q. I wanted to share my opinion - contrary to conventional wisdom - no variety of tea (green, white, or black) has any less or more caffeine than any other. The caffeine in any cup of tea is directly and solely proportional to the number of minutes steeping (it takes 15 minutes to extract 100% of the caffeine, which may be too much for good taste). (This also means that the idea that "steep for 30 seconds, throw out that tea because it will have most of the caffeine" is FALSE, a myth also.)So, in particular your statement: " A typical cup of green tea contains less than a cup of regular black tea." is false. In general, the widespread idea " In the evening, I'll drink green tea because it has less caffeine" is false.
   A. Thanks for writing to us.

Caffeine withdrawal
If you missed your morning coffee and now you have a headache and difficulty concentrating, you might be able to blame it on caffeine withdrawal. In general, the more caffeine consumed, the more severe caffeine withdrawal symptoms are likely to be.

Caffeine addiction
As little as one standard cup of coffee a day can produce caffeine addiction.

Caffeine overdose can cause nausea, diarrhea, light-headedness and urinary frequency.

Caffeine headache
Many people's headaches are related to their consumption of caffeine, most commonly in the form of coffee, tea, soft drinks, chocolate, and medications. Generally the headache is due to a "withdrawal" effect. Caffeine is very similar in structure to another chemical in our body called adenosine. One of adenosine's jobs is to dilate blood vessels in the head. Caffeine blocks this dilation. Your body then has to become more sensitive to adenosine to compensate. The only problem being that when caffeine is withdrawn, your body is overly sensitive to adenosine and blood vessels will dilate, creating a pounding headache.

Caffeine allergy
In very rare cases, caffeine can cause hypersensitivity or anaphylaxis.

Caffeine and cellulite
I have not come across any good evidence that caffeine ingestion reduces cellulite.

Does caffeine lead to weigh loss?
It appears that those who drink coffee or tea on a regular basis have a slightly less incidence of gaining weight over time.

Caffeine and high blood pressure
Adolescents, particularly black adolescents, who drink several soft drinks each day may increase their blood pressure and their risk for hypertension. In these situations, excess caffeine is deleterious to health. Caffeine free herbal teas are available widely.

Coffee, Caffeine and Heart Disease
Studies have produced mixed results.
   Heart attacks might be a risk for coffee drinkers with a common genetic trait that makes caffeine linger in their bodies. Research on more than 4,000 people in Costa Rica found that about half had the trait and were considered "slow caffeine metabolizers." The other half had the opposite trait, which caused their bodies to rapidly break down or metabolize caffeine, and coffee-drinking in this group appeared to reduce heart attack risks. Among slow-metabolizers, those who drank two or more cups of coffee daily were at least 36 percent more likely to have a nonfatal heart attack than those who drank little or no coffee. Even higher risks were found for younger slow metabolizers -- those under 50. They were up to four times more likely to have a heart attack than slow metabolizers in their age group who drank little or no coffee. The findings, though preliminary, might explain why there have been such mixed results in previous studies investigating caffeine's effects on the cardiovascular system. Caffeine is thought to block the effects of a certain chemical that is believed to help protect against tissue damage. Some previous research has linked coffee-drinking to a higher risk of heart disease, but other studies have suggested the opposite. While there's evidence to suggest caffeine can cause short-term blood pressure increases, a study last year said coffee-drinking didn't appear to cause long-term high blood pressure, at least in women.

In healthy volunteers, the equivalent of two cups of coffee reduces the body's ability to boost blood flow to the heart muscle in response to exercise, and the effect is stronger when the participants are in a chamber simulating high altitude. Whenever we do a physical exercise, myocardial blood flow has to increase in order to match the increased need of oxygen. Caffeine may adversely affect this mechanism. It partly blunts the needed increase in flow. The caffeine dose does not affect blood flow within the heart muscle while the participants are at rest. However, the blood flow measurements taken immediately after exercise were significantly lower after the participants had taken caffeine tablets. The effect was pronounced in the group in the high-altitude chamber. Caffeine may block certain receptors in the walls of blood vessels, interfering with the normal process by which adenosine signals blood vessels to dilate in response to the demands of physical activity. Although it is a stimulant, these results indicate that coffee may not necessarily boost athletic performance.

Caffeine for post exercise muscle pain
In a small study of female college students, a caffeine supplement seemed to lessen the familiar muscle pain that crops up the day after a particularly challenging workout. Known as delayed-onset muscle soreness, or DOMS, the pain is common in the day or two after a workout that was more intense than normal. Exercise that involves eccentric contraction of the muscles is particularly likely to cause delayed muscle pain. In eccentric contraction, the muscle produces a force while it's being lengthened. This happens when a person runs downhill, for example, or lowers a weight during a bicep curl. Researchers at the University of Georgia in Athens looked at the effects of a caffeine supplement on delayed muscle pain in nine young women. First, in a simulated workout, the researchers used electrical stimulation to produce eccentric contractions in the women's thigh muscles -- enough to cause moderate day-after soreness. Next, they repeated the procedure over the next two days, but on each day, the women took either a caffeine pill or placebo pill one hour before the muscle workout. Neither the women nor the researchers knew which pill was given on which day. Overall, the women reported significantly less muscle soreness during the workout when they took caffeine instead of the placebo. The supplement had about the amount of caffeine found in two cups of coffee. The theory is that caffeine eases delayed muscle pain by blocking the activity of a chemical called adenosine, which is released as part of the inflammatory response to injury. Adenosine can activate pain receptors in body cells, explained Victor Maridakis, the study's lead author. The negative side effects of caffeine are increased feelings of anxiety, heart palpitations, increased blood pressure, upset stomach, increased urination and disrupted sleep. Journal of Pain, February 2007.

Caffeine has significant hemodynamic and humoral effects in habitual coffee drinkers that persist for many hours during the activities of everyday life. Furthermore, caffeine may exaggerate sympathetic adrenal-medullary responses to the stressful events of normal daily life. Repeated daily blood pressure elevations and increases in stress reactivity caused by caffeine consumption could contribute to an increased risk of coronary heart disease in the adult population.

High Caffeine in Energy Drinks
Energy drinks that promise to boost performance and rev up metabolism can contain three to four times as much caffeine as a typical soda. Consumers who are vulnerable to the ill effects of caffeine -- including children, pregnant women and people with cardiovascular disease -- may unknowingly ingest large amounts.
Energy drinks like Red Bull, Red Devil and Sobe "No Fear" typically contain a mix of carbohydrates, B vitamins, amino acids and caffeine. Given the danger of high caffeine intake to some people, critics say energy drinks should be required to state their caffeine content clearly, The Food and Drug Administration has had a long-standing "proposed" rule that soft drinks limit their caffeine content to no more than 65 mg per 12-ounce serving. But neither sodas nor energy drinks are required to put their caffeine content on the label. Most soft drinks contain less than the recommended 65 mg of caffeine per 12 ounces. Most of the energy drinks, however, boast at least that much caffeine in an 8-ounce serving.

Drinking caffeinated green tea and coffee may protect women and overweight men against developing type 2 (non-insulin dependent) diabetes, according to a Japanese study. Among 17,413 men and women aged 40 to 65 who were free of diabetes at baseline, new cases of diabetes occurred in 231 men and 213 women over a 5-year follow up period. Compared to subjects who did not consume these caffeine beverages, those who reported drinking six or more cups of green tea per day were 33 percent less likely to develop type 2 diabetes. Those who reported drinking three or more cups of coffee per day were 42 percent less likely to develop the condition than non-coffee drinkers. Drinking black or oolong teas did not appear to protect against type 2 diabetes. These findings from a Japanese population mirror results obtained in European and US populations in which people who drank seven or more cups of coffee per day had a 29 to 52 percent reduced risk of diabetes compared with those who drank fewer cups of coffee per day or none at all. The researchers think these associations are mostly due to caffeine, because green tea and coffee are both major sources of caffeine in Japan. Annals of Internal Medicine April 18, 2006.

Q. Can caffeine by taken with lipoic acid, acetylcarnitine supplement or CoQ10?
   A. Anytime a stimulant nutrient or herb is taken with caffeine, there could be an unpleasant effect of overstimulation and restlessness which could occur with the combination of caffeine with the above mentioned nutrients and a number of herbs such as ginseng. I prefer limiting coffee intake to one cup in the morning when combined with such supplements.

Q. When I drink coffee it causes to have anxiety, is this common? Would kava help?
   A. Some people are very sensitive to caffeine and do get restless, irritability and anxiety even from one cup of regular coffee with caffeine. Some people even get anxiety from decaffeinated coffee either due to the caffeine remnants or the theobromine. Kava can help relieve anxiety, so can 5-htp.

Q. Are there any herbs which should not be used on days when caffeine is ingested?
   A. There are many herbs that have stimulating properties and it would be best to reduce the amount of caffeine ingested on those days. Some of these herbs include tongkat ali extract, horny goat weed, ginseng, lj100 and others.

Q. Hi Dr. Sahelian and company. This may be a strange question, and I'm not sure if it's too personal or specific to me, but:  I've been taking a (very) popular fat-burner for about three weeks now. This fat-burner of course contains much caffeine (the equivalent of two cups of coffee in each two-tablet serving, and this is for three times daily). The caffeine is in the form of green tea and other teas (same plant), as well as the Garcinia cambogia and Gymnema sylvestris. But I've noticed for about a week and a half now that I seem to have less libido (I'm a 25 year old male by the way), and I can't think of any other lifestyle or any other issue in the last MONTH or so that could be a contributing factor. The fatburner is the only change I've made. So can a high-dose caffeine fatburner possibly decrease libido -even though it's supposed to be stimulating otherwise? And I haven't found it otherwise stimulating either funny enough.
   A. It's possible that caffeine could cause shallow sleep or the other ingredients in the product could cause this decrease in libido. A good way to find out is by stopping the caffeine and the other supplements to see if the libido returns.

Q. What is it about coffee that kills inositol? I drink green tea, which has caffine, so I was wondering about the caffine.
   A. We are not aware of coffee or caffeine 'killing' inositol.

Q. On your information site about yohimbe, it states "I don't recommend you mix yohimbe with alcohol or stimulant drugs, including high doses of caffeine." Question: What constitutes high doses of caffeine?
     A. Each person is different, but more than one cup of coffee could contain enough caffeine be high for someone while more than 2 or 3 cups could be considered high for another. Caffeine can stimulate heart tissue and may contribute to palpitations in those taking yohimbe.

Q. I have a question about Mind Power RX. I was told to quit caffeine intake, therefore, I am looking for a replacement esp. for days when I do not get enough sleep. I know that caffeine improves mental performance and is found to provide restoration to almost complete rested state. However, how does Mind Power RX compare to caffeine intake (i.e., compared to 300 mg of caffeine intake per day)? In other words, does Mind Power RX provide as much improvements in all areas of mental performance as 300 mg of caffeine intake per day?
   Q. We have not compared the two but it is like comparing apples not just to oranges but to a vegetable since they are so different. Mind Power Rx has more than a dozen nutrients that influence mental function and herbs that stimulated brain function. The effects are very different.

Q. How would you compare the sleep disturbing effects of Passion Rx vs. coffee taken at the same time in the morning? I'm an occasional insomniac and sensitive to the effects of caffeine.
   A. Passion Rx is stronger than caffeine in terms of alertness, you may consider using half a capsule if you are prone to insomnia, and also it is a good idea to be physically active to use up excess energy.

Q. Can you possibly tell me how many mg of caffeine would be in 50 mg of green tea (leaf) extract?
   A. This is impossible to say accurately since there are countless extract potencies of green tea and countless varieties of green tea leaf and herb. The level of caffeine could vary significantly between different extracts, growers, processors, and manufacturers.

Q. I'm considering purchasing Mind-Power RX and MultiVit Rx, but I want to know if the "stimulating effects" result from caffeine. I try to avoid caffeine as much as possible.
   A. There is no caffeine in these products.