TL;DR Caffeine as a stimulant can be chemically addicting. People who love having a regular caffeine fix (like two or more cups a day) may develop “physical, emotional and psychological dependence on it and may experience a caffeine withdrawal syndrome after abrupt cessation of caffeine intake.” Caffeine withdrawal symptoms take place. But don't fret, there are ways to remedy it all.
It’s how most love stories begin.
Infatuated, they can’t get enough of each other, can’t stop thinking about each other. Every morning they wake up, every moment of the day, they long to have each other. A piece of each other is already enough to give them a strong jolt of bliss.
This is a love story that most of us coffee junkies have with our cup of joe.
We can only love our java so much, and there will come a time when we have to have a little less than what we’ve been used to.
Parting ways is an arduous process filled with pain, pining, and pure anguish.
(Okay, that may be too much but you know what I mean.)
Romance calls this passion. Science calls this caffeine withdrawal.
What is Caffeine Withdrawal?
Caffeine as a stimulant can be chemically addicting. People who love having a regular caffeine fix (like two or more cups a day) may develop “physical, emotional and psychological dependence on it and may experience a caffeine withdrawal syndrome after abrupt cessation of caffeine intake.” 
Why is caffeine addicting?
Most people just can’t get enough coffee. What makes it addicting and habit-forming has to do with how caffeine molecules fit perfectly into the human brain’s adenosine receptors.
Adenosine is a sleep-inducing molecule in your body that causes sleepiness. When adenosine binds to adenosine receptors in the brain, it slows down nerve cell activity, making you drowsy.
Here comes caffeine, which looks like adenosine. As an “adenosine receptor antagonist,” caffeine is recognized by the nerve cells and receptors as adenosine. When caffeine binds into the receptors, it blocks adenosine and inhibits the latter’s effects on your body.
So instead of slowing down nerve cell activity, caffeine does the complete opposite – it stimulates you! 
But Caffeine Informer explains why this activity makes caffeine so addicting: 
Over time, the brain adds more adenosine receptors to compensate for the caffeine, which causes a "tolerance" to build up to the caffeine molecule.
When a person misses or decides to quit their usual caffeine dosage, the brain is then flooded with adenosine and dopamine levels drop drastically causing the brain’s chemistry to be out of balance.
The increased adenosine plus a drop in adrenaline and dopamine levels lead to many of the caffeine withdrawal symptoms.
If you’re not sure if you’re having one too many cups of joe, then here are signs that you may be addicted to coffee part 1 and 2.
But how bad is caffeine withdrawal?
In a study from 2004, Johns Hopkins Medicine looked at the research on caffeine withdrawal and concluded about 50 percent of people who quit get symptoms, not just of headaches but other disorders too. 
‘Caffeine is the world’s most commonly used stimulant, and it’s cheap and readily available so people can maintain their use of caffeine quite easily. The latest research demonstrates, however, that when people don’t get their usual dose they can suffer a range of withdrawal symptoms, including headache, fatigue, difficulty concentrating. They may even feel like they have the flu with nausea and muscle pain.’—Roland Griffiths Ph.D., professor of psychiatry and neuroscience
Dr. Griffiths and his colleague, Laura Juliano of American University, surveyed 57 experimental studies and nine surveys on caffeine withdrawal to assess veracity of the studies’ findings. They were convinced years ago that caffeine withdrawal was so serious it should be included in the Diagnostic and Statistical Manual of Mental Disorders (DSM) and The International Statistical Classification of Diseases and Related Health Problems.
Caffeine intoxication and withdrawal are, in fact, considered mental disorders. (They’re currently included in the DSM.)
8 Signs and Symptoms of Caffeine Withdrawal
Sudden removal of caffeine in our diet is a sure-fire way to get withdrawal symptoms, which normally start within 12-24 hours of quitting. 
If you’re not sure whether you’re going through it or not, here are 8 common signs and symptoms of caffeine withdrawal:
Caffeine headache is actually a thing. Loading up on caffeine a little too much can result in tremors, nervousness, and sleep interruptions. When you develop caffeine dependence, trying to get rid of it and even having less than your usual fix can cause a headache – a clear symptom of withdrawals. Ironically though, caffeine can also cure the migraine. Read more in our article “Does caffeine cure or cause migraines?”
A study involving 213 regular caffeine consumers showed that abstaining from caffeine for 16 hours resulted in more amplified feelings of fatigue. And those who consumed caffeine daily developed more intense symptoms compared to those who had it less frequently. 
Here’s the double whammy – pulling the plug on caffeine won’t prevent anxiety and depression altogether.
According to Healthline, “anxiety is a commonly reported symptom in people who withdraw from regular caffeine consumption. The body can become mentally and physiologically dependent on it, causing feelings of anxiety.” 
We’ve all been there. Once quitting something so abruptly, we tend to get so moody that everything seems to be getting on our nerves.
And easing off on caffeine is a one-way ticket to cranky town.
Ever had a morning where you seem to have woken up on the wrong side of the bed? Yep – that’s because coffee only lasts 4-6 hours in our body and withdrawal-like symptoms kick in after your beauty sleep. 
If you think you’re suffering from brain fog during caffeine withdrawal, here’s why. Caffeine leads to a rise in adrenaline levels and an increase in brain activity. This is done through higher levels of dopamine and norepinephrine, hormones that help us concentrate.  
Cutting back on caffeine also gets rid of these benefits as the system will grapple for caffeine levels that used to fuel the former brain activity.
Abstaining from caffeine can cause lethargy. As a stimulant, caffeine delivers the much-needed energy boost to either get through the day or get a second wind.  But going overboard my lead to dependence, and suddenly withdrawing from caffeine might shock the system and leave it all sluggish.
A known side effect of going overboard with caffeine is jitters, and the adverse effect of going from hero to zero in no time is the same thing. Tremors normally happen with the hands and should only last for 2-9 days. If it persists, please consult a medical professional.
The next time you feel like you’re going down with the flu, check whether you just miss your usual dose of caffeine. Apparently, caffeine withdrawal may cause you to feel like you’re having a flu, with stuffy nose, blocked sinuses, hot and cold spells, and heavy limbs to boot.
These are the common symptoms that you’re going through caffeine withdrawal. They usually last from 2-9 days, the height of which is felt within 24-51 hours of deciding to quit.
Reduce Caffeine Withdrawal Symptoms
If you’re so set on cutting back on your caffeine, there’s a few steps you can take to veer away from the said symptoms.
Slowly but surely. Don’t be too hard on yourself. Going cold turkey might turn out to be counter-productive. Instead, wean off on your caffeine intake, one source at a time in a pace that’s comfortable for you.
Mix it up. Reduce your caffeine intake by mixing up caffeinated drinks with decaf. Gradually lower the amount of caffeine by going from full-strength coffee to half-decaf, half-regular coffee or tea, for instance.
Hydrate! Always bring with you a bottle of water, especially when cutting back on caffeine, as dehydration can worsen withdrawal symptoms. 
Go natural. Boost your energy by eating nutritious and healthy foods and exercising.
Get plenty of sleep. Fatigue is one of the most common symptoms of withdrawal so make sure you’re well-rested.
Caffeine withdrawal: how long does it last?
A regular coffee drinker and caffeine fix, when quitting it all too abruptly, will likely suffer from withdrawal effects from 12 to 24 hours upon easing off it. And the peak of withdrawal effects will normally take place 24 to 51 hours into it. 
While caffeine withdrawal symptoms may depend for each person, in general it commonly takes at least two to nine days before one gets in the clear. 
How much is too much caffeine?
Studies have shown that caffeine remains in the safe zone when consumed in low-to-moderate amounts . But what exactly does “low-to-moderate” mean?
The most important figure to remember on this topic is...
400 milligrams (mg).
That’s the amount of caffeine that’s considered safe to consume in a day… at least for adults. 
And if you’re wondering how much the “killer” amount is (literally), then USA Today reports it would “likely take anywhere from 50-100 cups of coffee,” or a teaspoon of pure powdered caffeine ingested at once. 
Now you must really love your caffeine to death if you take in that much!
Erectile dysfunction. In combination, those are two of the ugliest words known to man. But can caffeine help you get it up?
Science hasn't found the definitive answer to this question, but one study concluded that fewer men who consume caffeine have problems performing. The study said:
Caffeine intake reduced the odds of prevalent ED, especially an intake equivalent to approximately 2-3 daily cups of coffee (170-375 mg/day). This reduction was also observed among overweight/obese and hypertensive, but not among diabetic men. Yet, these associations are warranted to be investigated in prospective studies