Caffeine has a metabolic half life of 6-12 hours. This means that after a 24 hour period, there could be 1/4 of the original caffeine amount you drank in your system. If you drink the same amount of caffeine again at that point, now after a 24 hour period you ‘ll have up to 1/4 of that 1.25 amount in your system. If you consume caffeine daily, this can lead to an accumulation of caffeine that your body adjusts to always being there, becoming the new baseline normal. This would feel fine until you stop, at which point the caffeine your body expects to be there is gone, and it needs to take time readjusting to that absence. That leads to withdrawal symptoms.

People conflate "Addicted" and "Dependant". I'm not addicted to caffeine, but I will feel off by late morning if I haven't had some.

By drinking high doses over a long period of time. When I'm in withdrawal I get depressed and foggy with terrible headaches.

The good news is that it only takes a week or so to be completely free of withdrawal symptoms.

If you drink it regularly it's already got you

You say you drink it regularly, have you ever tried to stop? If you suddenly experience headaches and shakes after, I've bad news for you.

The thing is, caffeine addiction is so heavily normalized and encouraged by our capitalist society that most people do not realize they're addicted. They consume caffeinated products with enough regularity that they never crave it, and you're only ever encouraged to stop if you develop a health issue.

Takes a few months. Most notable symptom of withdrawal is usually headaches, lasts a day or two. It's not a severe addiction, it's a fairly mild one as they go.

Friend of mine used to drink quadruple espressos at Starbucks every day, then go back to work. I was talking to him last week and told him about remembering the time he called me from the Starbucks and his name was called with the quadruple order. He laughed and said he actually bumped it up to quintuple at one point.

Then he sold his house and moved to another state, living out in the woods. Asked him how he managed without a Starbucks nearby. He said he now does Keurig espresso shots every morning. But it was getting expensive, since he had to press 10 pods in one sitting!

Moral of the story: he's perfectly functional and productive. Go nuts!

with a hypodermic needle into the vein of your penis

I have relatives who would get headaches if they didn't get it. People's bodies respond differently.

How old are you? The side-effects or withdrawal symptoms didn't really become noticeable for me until my mid-30s...I went from feeling fine whether I had caffeine or not, to getting a headache in the afternoon if I missed my morning coffee, to waking up with a headache already that wouldn't go away until I upped my dose.

No clue. While I don't drink coffee, I did drink caffeinated sodas for a large part of my life. One day I just decided to stop drinking soda. I felt no sort of addiction or withdrawal symptom.

Get out while you still can. It's too late for me.

I don't like the taste of coffee, so I drink energy drinks. Energy drinks often have much more caffeine than a cup of coffee. for example, I drink Alani brand, they have a whopping 200(!) mg of caffeine per can.

When I drank one every day of the week at work, I then wouldn't drink any on the weekend because it didn't matter if I had energy. By Sunday I would have a day long caffeine headache and it was awful, but I refused to drink an energy drink JUST to stave off the headache because it made me feel like a junkie lol.

Instead, I now drink one every other day of the week, and I don't have headaches. That is how I chemically (not psychologically) became addicted to caffeine.

For some people, there is no addiction. I would swap between coffee and tea for my morning drink, but it was never an energy boost, just a warm drink for the winter months. Aside from that caffeine has no effect. I stopped drinking both cold turkey in an attempt to cut back on my sugar consumption and had no withdrawals.

You don't get 'addicted' to caffeine. If you consume it daily your body will adjust to the new baselines and discontinuing will have symptoms (headache for a day, tired, etc...), but it is not a clinical addiction.

Edit: caffeine does not have a "Substance Use Disorder", merely a "Withdrawal Syndrome" (DSM-V pg. 482)