6 Reasons Why Caffeine Doesn’t Affect You | Caffeine Tolerance

Caffeine is a highly active stimulant in coffee, tea, energy drinks, etc. People take caffeine for an energy burst or to improve mental alertness while studying or working. However, some people complain that caffeine doesn’t affect them.

Yes, it could happen that after two to three cups of coffee or two cans of cola, you still feel the same…unenergetic and feeling sleepy. It is a sign that caffeine doesn’t affect you anymore.

Low or no response to caffeine could be due to several reasons, which I will discuss in this article.

Why does caffeine not affect me?

Caffeine does not affect you for several reasons. They include:

1. Your caffeine consumption

You may be consuming too little caffeine, and that is why it does not affect you. If you are sure you are within the recommended daily maximum consumption (400 mg), you can take one more cup of coffee or a can of cola.

2. Fatigue

If caffeine does not seem to affect you anymore, you should check your stress level. It could be that your body is fatigued and needs the sleep you are trying to push away. You can’t cheat nature, you know?

So, if you have not been getting enough sleep, take a pause and a nap. When you are sure you have rested well, you can get to work or those books again without caffeine, for a start.

3. Genetics

Another reason caffeine does not affect you is genetics. Your genetic makeup determines how effectively your body’s adenosine receptors bind to the caffeine molecules (the process that determines caffeine action).

Your genetics also determine the rate of caffeine metabolism in your coffee. CYP1A2 is an enzyme in the liver that is responsible for caffeine metabolism.

There are two types of this enzyme; one metabolizes faster than the other. The type you carry in your liver depends on your genetics.

4. The diuretic effect of caffeine

Caffeine has diuretic properties, which is why you use the bathroom more often after drinking coffee.

When you use the bathroom too frequently, you lose fluid and become dehydrated. When you feel dehydrated, you become more tired, dizzy, and unable to stay awake.

5. Caffeine tolerance

The caffeine in your cup of Joe may not stimulate you if you have built a tolerance. Regular consumption of high amounts of caffeine can make you less sensitive or non-responsive.

A common solution is to take more caffeine, but, this is unhealthy and can have adverse effects.

6. Your medications are interacting with caffeine

Antidepressants, heartburn, stroke, thyroid, diabetes, stroke, and anti-anxiety medications can interact with caffeine in your coffee, cola, or energy drink.

These interactions could slow down caffeine metabolism and absorption, which is why you feel unresponsive afterward.

How long does it take caffeine to kick in?

It takes 15 minutes for the effect of caffeine to kick in. Within 30 minutes you should feel an energy burst or an alertness in my mind.

If you don’t experience this after drinking a cup of coffee, you may have another cup. As mentioned earlier, it could be because your body has built a tolerance to a certain amount of caffeine.

Does caffeine affect people with ADHD?

Caffeine shows varying effects on people with ADHD (attention deficit hyperactivity disorder). It worsens the symptoms in some people and eases the symptoms in others.

A report shows that 50% of people with ADHD also deal with anxiety. Caffeine-based tea like green tea contains L-theanine, an amino acid that increases dopamine levels and helps with anxiety.

Drinking green tea can help reduce hyperactivity and increase organization and prioritization skills in children with ADHD. A study showed that these children became happier after taking caffeine than children without ADHD.

Adults with ADHD who consumed caffeine showed improved reaction time, logical reasoning, better focus on repetitive tasks, lower impulsive or risky behaviors, and vigilance.

Caffeine is a vasoconstrictor and can reduce blood flow in areas of the brain that are overactive in ADHD.

On the flip side, taking caffeine can have a negative toll on people with ADHD. Some of these reactions include sleep deprivation, difficulty in concentration and remembering, and worsened insomnia.

Sleep difficulties are worse in people who consume higher amounts of caffeine.

Other potential side effects of overconsumption of caffeine in patients with ADHD are irritability, increased anxiety, rapid heartbeat, nausea, and stomach pains.

Caffeine also interacts with ADHD medications and aggravates symptoms.

Ultimately, caffeine reactions with ADHD vary with patients, medication, and amounts of caffeine consumed. Most importantly, healthcare professionals advise that caffeine should not partially or fully replace ADHD medications.

How long does caffeine last in the body?

Caffeine has a half-life of five hours. That is, it takes up to ten hours to get it completely out of your system. If you consume 300 mg of caffeine, after five hours, there will be 150 mg left in your body.

How long does it take to build caffeine tolerance?

Caffeine tolerance builds over time due to regular consumption of drinks and beverages that contain caffeine.

Caffeine works by blocking adenosine from binding to its receptors, increasing alertness. Over time, the body produces more adenosine receptors as caffeine level increases in the blood and more adenosine binds to these receptors.

As a result, the body builds caffeine tolerance. Regular caffeine consumption can raise blood pressure, decrease muscle strength, and increase fatigue during exercise, and a dependence on caffeine for mental alertness.

You can overcome caffeine tolerance if you reduce your caffeine intake or the frequency of consumption. Another solution is to increase your caffeine consumption but this is not advisable.

Side effects of caffeine

Excess caffeine consumption can cause headaches, insomnia, dizziness, dehydration, fast heart rate, dependency on caffeine, restlessness, and nausea.

Subsequently, these problems can progress into anxiety disorders and death.


How much caffeine is too much?

The recommended daily caffeine consumption is 400 milligrams (mg) per day. Anything above this figure is too much caffeine and could cause adverse effects.

You can get this from four cups of coffee, two shots of energy drink, or ten cans of cola.

Is high caffeine tolerance good?

A high caffeine tolerance is not 100% good or bad. As long as you are not taking too much caffeine, you should be safe.

A high caffeine tolerance simply means that your body is not experiencing the stimulating effects of certain amounts of caffeine.

How can you get caffeine out of your system?

To get caffeine out of your system, drink a lot of water, go outside for fresh air, take deep breaths, and eat a lot of fiber.

After doing any or all of these, sit patiently and wait it out. However, if you think you have gone beyond the recommended limit, you can see a healthcare provider.


Caffeine is a powerful stimulant but no two bodies are the same. While a small amount of caffeine may be enough to stimulate one person, double that amount may be needed to stimulate another person.

You may show low responsiveness to caffeine because of an energy dip, inadequate sleep, medications, or tolerance to your regular dosage.

Increasing the dosage is not always advisable, especially if you have hit the recommended daily consumption (400 mg).

If your caffeine sensitivity is becoming a concern for you, you should talk to a healthcare professional.

Check out the health benefits of taking caffeinated tea and the tea with the highest caffeine content.

Thanks for reading.