Caffeine: The Ultimate Guide For Your Healthy Drink


Did you know that you consume Caffeine

every time you sip from that cup of coffee or tea?


This guide explains everything you need to know about Caffeine.


You will learn what it is, the benefits, sources and how much is too much


Caffeine is a central nervous system stimulant of the methylxanthine class.

It is the world’s most widely consumed psychoactive drug.


Unlike many other psychoactive substances, caffeine is legal and unregulated in nearly all parts of the world


The consumption of up to 400 mg caffeine per day in healthy adults is not associated with the following:

  • Adverse cardiovascular effects
  • Behavioral effects
  • Reproductive and developmental effects
  • Acute effects, or bone status.

Evidence also supports the consumption of up to 300 mg caffeine per day in healthy pregnant women as an intake that is generally not,

associated with adverse reproductive and developmental effects.

Recommended Maximum Caffeine Intake Levels for Children and Women of Childbearing Age

 4 – 6 years   45 mg/day
 7 – 9 years   62.5 mg/day
10 – 12 years   85 mg/day


Women who are planning to become pregnant, pregnant women and breastfeeding mothers 300 mg/day Limited data were identified for child and adolescent populations;

the available evidence suggests that 2.5 mg caffeine per kg body weight in a day remains an appropriate recommendation.


Habitual daily use caffeine of more than 500–600mg which is the equivalent of four to seven cups of coffee or seven to nine cups of tea represents a significant health risk.

This is regarded as an abuse.


In North America, coffee (60–75%) and tea (15–30%) are the major sources of caffeine in the adult diet.


Caffeinated soft drinks and chocolate are the major sources of caffeine in the diet of children


Around 80% of the world population consumes it in one form or another



What Is Caffeine?

It is a central nervous system stimulant

A stimulant is an overarching term that covers many drugs including those that increase the activity of the central nervous system and the body.

They are pleasurable and invigorating, or drugs that have sympathomimetic effects.

This is the world’s most widely consumed psychoactive drug.

Unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world

It is a stimulant compound belonging to the xanthine class of chemicals


Is Caffeine A Drug? 

A drug is any substance other than food which provides nutritional support

Yes, it is the world’s most widely used psychoactive drug and by far the most common stimulant.

A psychoactive drug is a chemical substance that changes brain function and results in alterations in perception, mood, consciousness, cognition, or behavior

It causes a physiological and/or a psychological change in the body


Caffeine Is A Recreational Drug

It is used as a psychoactive drug to induce an altered state of consciousness for pleasure, by modifying the perceptions, feelings, and emotions of the user.

 Recreational drugs are in three categories: 

  • Depressant (drugs that induce a feeling of relaxation and calm)
  • Stimulants(drugs that induce a sense of energy and alertness)
  • Hallucinogens (drugs that induce perceptual distortions such as hallucination).

This drug increase alertness, attention, and energy by raising the levels of key chemicals in the brain and other parts of the body




What Are The Benefits Of Caffeine?


  •  It is used for the prevention and treatment of Broncho pulmonary dysplasiain premature infants
  • Caffeine reduces the incidence of cerebral palsy
  • It reduces language cognitive delay
  • Treatment of apnea of prematurity
  • It is used for orthmostatic hypotension
  • Enhances performance
  • Reduces fatigue and drowsiness
  • Improves reaction time, weakness, concentration, and motor coordination
  • Delays or prevent sleep
  • Improves task performance 
  • Caffeine improves athletic performance especially in endurance sports
  • It improves muscular strength and power



What Are The Sources Of Caffeine?

It is a natural chemical found in coffee beans, Tea plants


Major sources of caffeine were coffee (71%), soft drinks (16%), and tea (12%).

Coffee was the major source of caffeine in the diets of adults, whereas soft drinks were the primary source for children and teens.


It is also extracted by sipping and added to soft drinks and energy drinks.


Cocoa and chocolate products are also important sources of Caffeine

It occurs naturally in many plants,  coffee beans, tea leaves, and cocoa nuts.

It is artificially added to many other products, including a variety of energy drinks.




What Are The Side Effects Of Caffeine?

Positive Side Effects 

  • Do you know that moderate daily caffeine intake at a dose level up to 400 mg per day is not associated with adverse effects such as:
  • General toxicity
  • Cardiovascular effects
  • Effects on the bone status and calcium balance (with consumption of adequate calcium)
  • Changes in adult behavior
  • Increased incidence of cancer and effects on male fertility.
  • The data also show that reproductive-aged women and children are ‘at risk’subgroups who may require specific advice on moderating their caffeine intake




What Are The Negative Effects Of Caffeine?

You are at health risk when your habitual daily use of caffeine is greater than 500–600 mg or four to seven cups of coffee

This is regarded as abuse.

Sustained abuse may in result in caffeinism



What Is Caffeinism?

It is a condition of intoxication due to the abuse of caffeine.


Caffeine Intoxication

Caffeine intoxication is a state of stimulation of your central nervous system due to caffeine overdose

This occurs when you ingest more than 400-500 mg of caffeine at a time

It is considered as one of the most widely consumed drugs around the world.


The symptoms of  intoxication are comparable to the symptoms of overdoses of other stimulants

Caffeine intoxication is a syndrome characterized by a range of adverse reactions such as:


  • Restlessness, anxiety, irritability, agitation, muscle tremor, insomnia.
  • Headache, diuresis, sensory disturbances (e.g. tinnitus), cardiovascular symptoms (e.g. tachycardia, arrhythmia)
  • Gastrointestinal complaints (e.g. nausea, vomiting, diarrhea) (James and Paull 1985).


Treatment Of  Caffeine Intoxication

  • The treatment is directed toward symptom relief.
  • Severe intoxication may require peritoneal dialysis, hemodialysis or hemofiltration


An attempt to abruptly quit all consumption of caffeine-containing products from the diet is not recommended, because you could suffer from the resulting symptoms of caffeine withdrawal such as:

Headache, fatigue, and difficulty concentrating can be so unpleasant that this approach probably will fail.


It is recommended that the person performs a gradual reduction in caffeine use to avoid withdrawal



How Much Caffeine Is Too Much?

Up to 400 milligrams (mg) of caffeine, a day appears to be safe for most healthy adults. That’s roughly the amount in four cups of brewed coffee




 Caffeine Overdose. 

According to the Mayo Clinic, the recommended amount of caffeine is up to 400 milligrams per day for healthy adults.

Caffeine overdose occurs when you ingest more than this amount.

Adolescents should limit themselves to no more than 100 mg of caffeine per day


Overdose does result in a state of excessive stimulation of the central nervous system 


This diagnosis requires the presence of at least five signs or symptoms, from a list of 12, that develop during or shortly after caffeine use.


Overdose is a syndrome which regularly happens when you ingest a large amount of caffeine from any source (e.g., more than 400–500 mg at a time).


The signs and symptoms are divided into one group that can appear after intake of as little as 100 mg 


  1. restlessness,
  2. nervousness,
  3. excitement,
  4. insomnia,
  5. flushed face,
  6. diuresis (increased urination), and
  7. gastrointestinal disturbance.
  8. muscle twitching,
  9. the rambling flow of thought and speech,
  10. tachycardia and cardiac arrhythmia,
  11. periods of inexhaustibility, and
  12. psychomotor agitation.


How much does it take to overdose on caffeine?

You are already overdose when you consume more than 400 mg in a day

A single cup of coffee, which contains 100 mg of caffeine, brings blood levels up to about 5 or 6 mg/L.

The blood levels of the people who died of an overdose, according to the 2017 paper, averaged 180 mg/L, hence the 30 cups of coffee consumed in quick succession it would take to get to those lethal


 Mild Physical Dependence 

It results from excessive intake.

Studies have demonstrated that people who take in a minimum of 100 mg of caffeine per day (about the amount in one cup of coffee) can acquire a physical dependence.


This would trigger withdrawal symptoms that include:

  • Headache and muscle pain
  • Stiffness, lethargy, nausea, and vomiting
  • Depressed mood, and marked irritability.

A researcher at Johns Hopkins in Baltimore strongly believes that caffeine withdrawal should be classified as a psychological disorder.

His research suggested that withdrawals began within 12–24 hours after stopping the intake and could last as long as nine days.

It can occur in anyone who regularly consumes caffeine and then abruptly discontinues its use.




Caffeine Withdrawal symptoms

  • Common symptoms include:
  • Headache, fatigue, low energy
  • Irritability, anxiety, poor concentration
  • Depressed mood, and tremors, which can last anywhere from two to nine days.




How long does caffeine withdrawal last.

The duration of withdrawal symptoms vary from person to person, but withdrawal usually lasts at least two to nine days.

When you abruptly stop caffeine intake after regular use you will usually feel withdrawal effects between 12 and 24 hours after stopping




Addiction is a brain disorder characterized by compulsive engagement in rewarding stimuli despite adverse consequences


Studies have demonstrated that people who take in a minimum of 100 mg of caffeine per day (about the amount in one cup of coffee) can acquire a physical dependence.


Physical dependence triggers withdrawal symptoms that include:

  • Headaches, muscle pain, and stiffness.
  • Lethargy, nausea, vomiting
  • Depressed mood, and marked irritability

The term addiction is misused frequently to refer to other compulsive behaviors or disorders, particularly dependence

An important distinction between drug addiction and dependence is that drug dependence is a disorder in which cessation of drug use results in an unpleasant state of withdrawal


Addiction is the compulsive use of a substance or performance of a behavior that is independent of withdrawal.

It is not all drugs that produce physical dependence that are addictive drugs, e.g., caffeine


Substance dependence, also known as drug dependence, is an adaptive state that develops from repeated drug administration, which results in withdrawal upon cessation of drug use.

Drug withdrawal is the group of symptoms that occur upon the abrupt discontinuation or decrease in the intake of medications or recreational drugs.

In order for the symptoms of withdrawal to occur, one must have first developed a form of drug dependence.


 Drug Dependence

It develops from consuming one or more substances over a period of time.

Caffeine addiction or a pathological and compulsive form of use has not been documented in humans.

Unlike most stimulants, caffeine has no addictive potential.

Addiction is when you continue to seek out and take the drug even though you know it is damaging your health and life


The two properties that characterize all addictive stimuli are that they are:

  • Reinforcing (i.e., they increase the likelihood that a person will seek repeated exposure to them) 
  • Rewarding (i.e., they are perceived as being inherently positive, desirable, and pleasurable




What Are The  Caffeine Effects On The Following:

Blood Pressure

Blood pressure (BP) is the pressure of circulating blood on the walls of blood vessels.

Most of this pressure is due to work done by the heart by pumping blood through the circulatory system.

Used without further specification, “blood pressure” usually refers to the pressure in large arteries of the systemic circulation.

Blood pressure is usually expressed in terms of the systolic pressure(maximum during one heartbeat) over diastolic pressure (minimum in between two heartbeats) and is measured in millimeters of mercury (mmHg), above the surrounding atmospheric pressure.

The effect of caffeine on blood pressure in habitual consumers and abstainers has been investigated in more than 50 acute and 19 repeated-dose clinical trials with healthy or hypertensive subjects (reviewed by Myers 1988, 1998, James 1991c, Green, et al. 1996).


The results of the acute studies indicate that it induces an increase in systolic (5–15 mmHg) and/or diastolic (5–10mmHg) blood pressure, most consistently at doses >250mg/person, in adults of both sexes, irrespective of age, race, blood pressure status, or habitual caffeine intake



Heart rate

Heart rate is the speed of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm).

The heart rate can vary according to the body’s physical needs, including the need to absorb oxygen and excrete carbon dioxide.

It is usually equal or close to the pulse measured at any peripheral point. Activities that can provoke change include physical exercise, sleep, anxiety, stress, illness, and ingestion of drugs.

The American Heart Association states the normal resting adult human heart rate is 60–100 bpm

Tachycardia is a fast heart rate, defined as above 100 bpm at rest

It works by increasing the rates of depolarization at the SA node



Sleep is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings.

It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than coma or disorders of consciousness, sleep displaying very different and active brain patterns.

During sleep, most of the body’s systems are in an anabolic state, helping to:

Restore the immune, nervous, skeletal, and muscular systems


These are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems


It typically prolonged sleep latency, reduced total sleep time and sleep efficiency, and worsened perceived sleep quality.


Dose- and timing-response relationships were established.

The sleep of older adults may be more sensitive compared to younger adults

It may disturb sleep, but only in sensitive individuals.




Alertness is the state of active attention by high sensory awareness such as being watchful and prompt to meet danger or emergency or being quick to perceive and act.

It has many positive actions in the brain and can increase alertness and well-being, help concentration, improve mood and limit depression




In older adults, memory is typically best in the morning and gradually declines over the day.


Those who consumed caffeine in the morning showed much better memory, both short-term and long-term than those who consumed a placebo, especially in the late afternoon, where memory and attention may be most crucial to daily functioning for the elderly.


This is further supported by a study which showed that adults over the age of 65 who regularly consume caffeine in the morning are much more alert and function at a higher cognitive level throughout the day.


The authors conclude that it is beneficial for older adults to regularly consume average doses of caffeine in the morning to boost cognitive performance and alertness in the afternoon.

Again, one should not exceed the recommended dose of about 300 mg per day, otherwise, memory performance declines due to over-consumption.




Food Regulation Authorities have concluded that coffee/caffeine consumption is not harmful if consumed at levels of 200 mg in one sitting (around 2½ cups of coffee) or 400 mg daily (around 5 cups of coffee).

In addition, it has many positive actions in the brain. It can increase alertness and well-being, help concentration, improve mood and limit depression.

It may disturb your sleep, but only in sensitive individuals. It may raise anxiety in a small subset of, particularly sensitive people.

Coffee intake can be part of a healthy balanced diet if

its consumption does not exceed the recommended dosage per day



If You Have Enjoyed This Article Please Subscribe Below






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. [updated 2012 Feb 16; cited 2012 Sep 19]. Health Canada2012

FDA to investigate added caffeine [Internet]

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Washington (DC US Food and Drug Administration

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“Effects of caffeine on blood pressure, heart rate, and forearm blood flow during dynamic leg exercise”Journal of Applied Physiology. 85 (1): 154–9. doi:10.1152/jappl.1998.85.1.154PMID 9655769.

Lovett, Richard (24 September 2005). “Coffee: The demon drink?” (fee required). New Scientist (2518). Archived from the original on 24 October 2007. Retrieved 2007-11-19.

.Malenka RC, Nestler EJ, Hyman SE (2009). “Chapter 15: Reinforcement and Addictive Disorders”. In Sydor A, Brown RY. Molecular Neuropharmacology: A Foundation for Clinical Neuroscience (2nd ed.). New York: McGraw-Hill Medical. p. 375. ISBN 9780071481274. Long-term caffeine use can lead to mild physical dependence. A withdrawal syndrome characterized by drowsiness, irritability, and headache typically lasts no longer than a day. True compulsive use of it has not been documented.


Juliano, L. M.; Griffiths, R. R. (2004). “A critical review of caffeine withdrawal: Empirical validation of symptoms and signs, incidence, severity, and associated features”. Psychopharmacology. 176 (1): 1–29. doi:10.1007/s00213-004-2000-xPMID 15448977.

Ryan, L; Hatfield, C.; Hofstetter, M. (2002). “Caffeine reduces the time of day effects on memory performance on older adults”. Physiological Science. 13(1): 68–71. doi:10.1111/1467-9280.00412PMID 11892781.

Iancu, I; Strous, RD (February 2006). “Caffeine intoxication: history, clinical features, diagnosis, and treatment”. Harefuah. 145 (2): 147–51, 163–4.


(C) Safecaff 2019


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