Why Doesn’t Caffeine Affect Me? (Reasons And How To Fix It)

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why doesn't caffeine affect me

You finished your fourth cup of coffee, but you’re still yawning?

You’re probably asking yourself why doesn’t caffeine affect me.

Well, I’ve been there, and I understand that it’s a bummer. That’s why I did thorough research and found out there are a couple of reasons for this.

Keep on reading because I will explain what can cause your caffeine tolerance and what to do about it.

Let’s start!

Why Doesn’t Caffeine Affect Some People 

Caffeine is probably the most commonly used psychoactive substance in the world.

As you read this, millions of people all over the world are sipping coffee or some other caffeine-infused drink.

For me, caffeine is regular support when I have a busy and demanding day ahead of me.

But what if you drink coffee and don’t feel any effect of caffeine?

Is that even possible?

In order to understand why you don’t feel any caffeine alertness, we need to figure out what caffeine consumption actually does to you.

When you drink a caffeinated drink, it takes about 30 to 60 minutes to feel the stimulating effects.

Your liver is the one in charge of metabolizing caffeine. A 200 mg of caffeine takes about 40 hours to be completely metabolized.

Yet, you will feel effects only for the first 4 to 6 hours.

Caffeine molecules that aren’t broken by the liver end up in your brain. And this is where the magic is happening.

Here’s how:

Caffeine acts as a stimulant for your central nervous system.

Adenosine is a neurotransmitter that is an important part of your sleep-wake cycle. When adenosine binds to its receptors, it will make you feel it’s time for rest or sleep.

Caffeine and adenosine have the same “shape”, so caffeine binds to adenosine receptors.

That way, caffeine blocks adenosine from binding to the adenosine receptor and making you feel tired.

It also messes up your dopamine. Dopamine is also a neurotransmitter. One of its roles is to make you feel pleasure and happiness. Caffeine allows more dopamine to bind to its receptors.

A few chemical reactions later, you feel awake and energized.

It’s important for you to get this:

Caffeine won’t give endless energy and cover your need for rest.

It will just trick you into not feeling the tiredness.

Now, let’s see which factors can cause that caffeinated beverage doesn’t affect you.


Your genetics plays a big role in how you will react to caffeine.

Scientists find out that almost 10% of people genetically feel less or no caffeine effects.

First, how fast your body will metabolize caffeine is very important.

One particular enzyme in your liver, called CYP1A2, is responsible for 95% metabolization of caffeine. But, scientists found two forms of this enzyme.

One of these metabolizes caffeine faster than normal. That means caffeine will go faster through your body, and you will be left with less or no caffeine buzz.

Second, how much you will feel caffeine depends on how well adenosine receptors can bind caffeine molecules.

Unfortunately, if your genetics is what makes you resistant to caffeine, the is not much you can do about it.

You will just need to find other ways to keep yourself energized.


woman drinking coffee

Usually, I’m good with just one or two cups per day. If I’m drinking my third coffee in a day, I know I will build up my caffeine tolerance.

It’s simple as that: if you use stimulants like caffeine too much, your body will get used to it.

And, you will need a higher dosage to feel regular effects.

The recommended amount of caffeine for an adult person is about 400mg of brewed coffee per day. That’s about 4 cups of coffee.

If this much isn’t enough for you, you’ve probably built up your tolerance to caffeine.

Be careful. Too much caffeine can cause some serious problems like high blood pressure and even a heart attack eventually.

Luckily, you can fix this situation. Just take a break from coffee, energy drinks, soda, tea, or other caffeine-infused stuff.

My advice is don’t cut out caffeine cold turkey. Caffeine withdrawal can make you anxious, less focused, grumpy, give you a headache, and mess up your sleeping cycle.

Reduce caffeine intake gradually, and you should be just fine.

Not enough sleep  

This maybe didn’t occur to you, but maybe you don’t feel caffeine effects because you are TOO TIRED!

I’m not joking. If you’re not getting enough sleep and rest, caffeine won’t help you anymore at some point.

Adenosine is what tells your brain you need sleep.

When caffeine blocks adenosine receptors for too long, your body will start to produce more adenosine to fight caffeine.

The solution is simple: get some well-deserved sleep. Give your body time to rest and reset.

What Exactly Is the Effect of Caffeine? 

a woman drinking coffee

Scientists studied the effect of caffeine on the human body for a long time.

At first, caffeine was labeled as a “bad guy”.

But more recent studies show that caffeine, besides making you a functional human being in the morning, also has other benefits for your body.

They say that moderate coffee intake (2-5 cups a day) is linked to a lower likelihood of:

  • type 2 diabetes
  • heart disease
  • liver and endometrial cancers
  • Parkinson’s disease
  • depression

Common positive effects of caffeine on your body are:

  • alertness
  • energy
  • ability to concentrate and memorize 
  • anti-inflammatory properties
  • affect weight loss
  • reduces fatigue

But, if you overdose on caffeine, you may experience some negative effects:

  • jitters
  • insomnia
  • headaches
  • increased blood pressure and heart rate
  • anxiety, irritability
  • frequent need to go to the toilet (No.1 and No.2! )
  • increased risk of osteoporosis
  • muscle tremors

If you’re feeling the negative effects of caffeine, but still love the taste of coffee, you can try decaf coffee. Decaffeinated coffee is a great alternative for coffee drinkers who need to quit caffeine consumption for one reason or another.

Caffeine Alternatives To Boost Your Energy Level

woman drinking water

Hey, if caffeine doesn’t affect you, it’s not the end of the world.

There are still plenty of ways to boost your energy levels besides drinking coffee or energy drink.

Here are just a few examples of what you can do to recharge your batteries:

  • ensure a good sleeping cycle every night
  • exercise
  • stay hydrated
  • eat healthily
  • try caffeine alternatives like Ginko Biloba
  • go outside and take a walk

And who knows?

Once you have a break from the coffee consumption, maybe even a moderate amount of caffeine will work for you afterward.


And there you have it:

You can feel less or none of the caffeine effects due to your genetics. It can also happen as a consequence of having too much caffeine.

Keep in mind that caffeine isn’t a magic potion that will keep you awake forever. It is just a stimulant. And if you’re too tired, it won’t help you anymore.

Although you can’t change your genetics, two other causes can be prevented. Don’t drink too much coffee and have a regular sleep.

Want to take a break from caffeine, but don’t want to quit coffee? Check out the best decaf coffee beans that are equally delicious as regular coffee.

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Tijana Veljovic
Tijana spent a few years working as a barista. Now she’s enjoying writing about everything she learned about coffee and sharing it with you. Her weapon of choice for making it through the day is a hot latte. Besides writing and coffee, she loves traveling, camping, cooking, and good music.