Caffeine sensitivity: all you need to know

by Tina Sendin October 18, 2018 5 min read

Caffeine sensitivity: all you need to know

Have you been drinking coffee for years and are starting to feel weird sensations after a cuppa?

You’ve got to know something.

If you suddenly find yourself going through unusual post-caffeine effects such as anxiety, headache, faster heartbeat and tremors, you may be experiencing a shift in how your body metabolizes caffeine.

Two words: caffeine sensitivity.

According to Caffeine Informer: [1]

Caffeine sensitivity is determined by the efficiency of the human body to process and metabolize caffeine.

This shouldn’t be confused with caffeine tolerance, which describes how the body responds to caffeine over time.

Caffeine sensitivity is not necessarily a bad thing. Sometimes, it’s all a matter of our body adapting to caffeine in our system.

However, if all of a sudden you start to feel things that didn’t used to happen after having your java fix, then it’s time to watch that caffeine intake!




Levels of caffeine sensitivity

There are three kinds of caffeine consumers - those who experience intense reactions to it at minimal amount, those who can go overboard because having way too much doesn’t really affect them, and those who are somewhere in the middle.

In scientific terms, people are divided according to three levels of caffeine sensitivity:

Normal sensitivity

This is where the majority of the people fall under. With normal sensitivity, they can consume up to 400 milligrams of caffeine in a day and not experience anything unpleasant. [2]

(Related article: Here’s how much caffeine you should have in a day)

If you normally consume caffeine in the morning and can go on the day without feeling any of caffeine’s bad rap, i.e. jitters, palpitations, anxiety, then you’re part of this group!


A 2011 study identifies 10 percent of the entire population to be hyposensitive. They have the ability to consume caffeine at a higher-than-normal dosage and not experience any adverse effects. [3]

If you find yourself drinking coffee until late afternoon - or even at night - and still hit the hay without any difficulty, then consider yourself hyposensitive to caffeine. 


Those who fall under this category experience amplified effects of caffeine even at a small dosage, say 100 mg.

If you notice that you go through negative effects like a headache, insomnia, tremors, and palpitations with a few sips of tea or coffee, then your body must be taking longer to metabolize caffeine.




What causes caffeine sensitivity?

Caffeine sensitivity is not a random phenomenon that can just happen to any coffee-lover like you. There are a number of factors why you respond to caffeine the way you do:


Certain medications react to caffeine differently. The medicine you take may either amplify or diminish its effects on your body. If you want to find out which medicines have reactions to caffeine, you may check out this article, “Caffeine and medication: can you combine them?

Genetic link and brain chemistry

The body’s ability to metabolize caffeine depends on your genetic makeup:

  • The liver breaks down caffeine through an enzyme called CYP1A2. The body produces this enzyme with the help of the CYP1A2 gene, the DNA sequence of which tells how well your body can metabolize caffeine and gets rid of it from the body. [4] Caffeine sensitivity depends on how much of this enzyme is found in your body.
  • What regulates the function of CYP1A2 gene has something to do with the AHR gene. 10% of the population has enough AHR gene that causes them to be hyposensitive to the effects of caffeine. [5]
  • Caffeine’s effects also depend on the number of adenosine receptors in your brain.“How does caffeine keep you awake” explains exactly what happens when caffeine interacts with your body:
Your body breaks down a high-energy molecule called ATP, which is needed for its constant supply of energy. As it performs this function, it liberates adenosine, 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.


Because caffeine binds to adenosine receptors, its effects depend on the type of receptors found in your brain (correct ones should exist to get the most of your caffeine fix). [6]

  • A 2012 study reports that people experience heightened effects of caffeine because of the ADORA2A gene. Those with this gene tend to be hypersensitive to caffeine. [7]

Pregnancy and taking oral contraception

Caffeine sensitivity becomes more likely when a woman takes oral contraception or becomes pregnant. This is because of higher estrogen levels, which hampers CYP1A2 from fully functioning.

According to "Is caffeine safe during pregnancy?"

Having a bun in the oven slows down the body’s ability to break down caffeine, so higher levels of caffeine stay longer in the bloodstream. The farther along you are, the longer caffeine stays in your system, and the more intense its effects are in your body. [8]


What does caffeine sensitivity look like: signs and symptoms

While not necessarily detrimental, caffeine sensitivity may bring about inconvenience and discomfort.

According to Medical News Today and Healthline, here are some signs and symptoms of coffee sensitivity: [9, 10]

feelings of jitteriness and unease


 anxiety or nervousness

trouble sleeping or insomnia

 upset stomach

abdominal cramps

elevated heartbeat or blood pressure

involuntary muscle spasms



How can you overcome caffeine sensitivity?

If you're hypersensitive...

The most logical - albeit not the easiest - way to get rid of caffeine sensitivity is to take it easy on your caffeine fix. It makes total sense to try easing off on your go-to caffeine (or rid it altogether if you can). 

Be extra cautious on your caffeine intake. It doesn't hurt if you'd start reading the label more and monitor your caffeine mg's. Find out up to what amount of caffeine your body can take and stick to it.

Veer away from highly caffeinated products. Try switching to decaf or have some black or green tea instead.

You may find more tips on laying low on caffeine in the article, "Caffeine withdrawal symptoms and how to reduce them.


If you're hyposensitive...

Ask yourself this existential question - why do I still drink coffee?


But humor aside, since you don't necessarily get the positive effects of caffeine (you seem to be immune in it anyway), assess whether you still get any advantage from getting caffeinated. Otherwise, you may as well switch to decaf so you can steer clear of the adverse effects of consuming caffeine over a long period. [11]


If you have normal sensitivity...

Just always remember the acceptable amount of caffeine and don't go overboard. Here's how much caffeine you should have in a day.

You can also check how much caffeine is in your favorite brand of coffee here.


What kind of caffeine sensitivity do you think you have? Got any tips on how to overcome it? Leave them in the comments section below! 

Tina Sendin
Tina Sendin

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