Sebastian Freidank - 12. February 23

Caffeine side effect – All caffeine side effects on health


In this article, in addition to our extensive general post on caffeine, we want to be more specific about its health side effects.

We hope to give you an in-depth understanding of caffeine, which is such a widespread active ingredient, so that you can ultimately decide for yourself whether, when and how much caffeine you want to consume. Of course, to go with that, we also have an article on the health benefits of caffeine .


  1. How does caffeine work?
  2. caffeine side effects
    1. Health caffeine side effects on the body
      1. blood sugar levels
      2. pregnancy
      3. fertility
      4. gout
      5. Bladder weakness and bladder infection
      6. insomnia and sleep disorders
      7. Headache
      8. tachycardia
    2. mental side effects
      1. depression and anxiety
      2. loss of motivation
  3. Conclusion

1. How does caffeine work?

Caffeine is one of the few active ingredients that can cross the brain-blood barrier. It blocks the adenosine receptors in the brain. Adenosine, in turn, plays a role in the production of the sleep hormone melatonin.

By blocking the receptors, no, or more precisely less, melatonin is produced and we stay awake. Caffeine also has other effects such as decreasing dopanine efflux from the brain, increasing the heart's pumping capacity, being a diuretic and having an effect on general brain function.

2. Caffeine side effects

Caffeine is the most widely used legal drug in our society. Anyone who has ever had a caffeinated beverage like coffee or guayusa will know why. It has numerous benefits that we can take advantage of. You can find out about the positive effects caffeine has on our health and general well-being in our article specifically on the benefits of caffeine . There we also go into more detail about what biohacking with functional foods means. In this post, however, we focus on the possible side effects.

2.1. Health caffeine side effects on the body

In addition to some side effects on our psyche, caffeine can trigger a number of problems in our body if the dose is too high.

Caffeine side effect on physical health

blood sugar levels

Many people with type 2 diabetes and some studies report an increase in blood sugar levels after consuming caffeine.

The studies describe an influence on the insulin level, especially when caffeine is consumed directly with or after a meal. The blood sugar level can then rise up to 8% higher than without caffeine. However, in the study , subjects were also given caffeine pills containing 250 mg of the active ingredient. This makes a difference to a natural caffeine intake from a drink like guayusa .

So caffeine can have an impact on our insulin sensitivity, which can be a very negative side effect, especially as a type 2 diabetic. Pure caffeine should therefore be avoided at all costs and the consumption of natural sources should be preferred.

Guayusa has been shown in a study to stabilize the body's insulin balance instead of disrupting it. The tea from Ecuador with the highest caffeine content in the world can be a great alternative to coffee, mate, green tea and guarana.


The WHO recommends a maximum of 300 mg of caffeine per day to avoid side effects on health. The BfR, on the other hand, already caps the amount at 200 mg.

A higher intake can lead to the following problems:

  1. loss of pregnancy
  2. Slow baby growth
  3. cardiac arrhythmias in babies

Caffeine side effects on pre- pregnancy health were also studied . The recommendation for both partners is to reduce consumption to a maximum of 200 mg per day to increase the likelihood of pregnancy.

If you would like to learn more about the topic of the effect during pregnancy, we have written an extensive individual article here .


Some studies have come to the conclusion that the health of the fallopian tubes or the muscular activity of the fallopian tubes can decrease by up to 27% with increased caffeine consumption. In a US study, more than 300 mg of caffeine were consumed per day and in a European study, around 500 mg.

No negative effects on sperm were found in men.


Small amounts of the caffeine that is consumed pass into breast milk and is thus also absorbed by the baby. The highest level is measured about 1 to 2 hours after consumption. So it's not so easy, especially with newborns, to find a good rhythm for drinking a cup of your favorite pick-me-up.

In general , however, it also applies here that the dose makes the poison. 200mg to 300mg of caffeine per day consumed by the mother is considered safe for the baby's health. Some babies may not react at all to the small amounts in breast milk, others have their eyes open a little longer as a small side effect of caffeine and appear restless.

You can also find a detailed article on the subject of breastfeeding here .


Gout sufferers should avoid caffeine if possible. Up to 4 times more likely to have an attack after drinking caffeinated beverages.

Bladder weakness and bladder infection

Caffeine can cause increased urine output as a side effect. A study of over 1,300 women found that women were 70% more likely to experience bladder weakness if they consumed more than 300 mg per day.

Incidentally, caffeine should be avoided at all costs if you have a bladder infection, as it worsens the symptoms. People who are more prone to bladder infections can reduce their chances of getting another infection by cutting down on caffeine.

This is because caffeine has a diuretic side effect on health and is therefore slightly dehydrating.

insomnia and sleep disorders

Another caffeine side effect that can affect health as a secondary effect is insomnia. Too little or disturbed sleep impairs brain functions and can lead to depression.

Studies on caffeine intake and its side effect on sleep health indicate that the last consumption should be at least 6 hours before bedtime. Everything else leads to a reduction in sleep quality.


A population-wide study found a link between chronic headaches and long-term high caffeine consumption. A high consumption is to be rated at more than 300 mg daily.

However, caffeine can also reduce headaches as a positive side effect and thus provide a health benefit .


Normal consumption of caffeinated beverages leads to a slightly increased heartbeat, but usually no negative side effects such as strong and uncomfortable tachycardia, especially not when it comes to Guayusa. Caffeine also widens the blood vessels, which creates a balance.

On the other hand, caffeine consumption that is clearly overdosed usually leads to very unpleasant tachycardia, tremors and a feeling of pressure in the chest area. Coffee, on the other hand, quickly triggers heart palpitations in many consumers. This is due to the nearly exposed (unbound) caffeine, which can work directly like pure caffeine powder .

2.2. Mental caffeine side effects

In addition to the physical side effects mentioned , caffeine can also have negative effects on our psyche. As with the aforementioned physical side effects, the mental ones usually only occur over a long period of time if the dose is too high.

Caffeine side effects on mental health

depression and anxiety

The opinion and study situation on this is not clear for us. Some people report caffeine side effects such as mild anxiety and depression-like feelings on days with particularly high caffeine consumption, while others do not notice this.

Studies also differ on this. So describes z. For example, a study with Korean students found a significantly higher proportion of depression, while other studies describe a decrease.

loss of motivation

This side effect is more akin to caffeine withdrawal than a direct side effect. Because caffeine slows the release of dopamine from our brain into the body, causing it to build up in the brain, withdrawal creates what feels like a lack of dopamine.

Dopamine, in turn, ensures that we can feel joy, motivation, and fulfillment.

3. Conclusion

The dose makes the poison and so it is with caffeine. You should be particularly careful with pure, i.e. extracted caffeine powder. This pure caffeine is mostly found in pills, capsules and drinks and has a much more aggressive side effect on our health. We have described the difference to natural caffeine in our comparison here .

You should not consume more than 300 mg of natural caffeine per day and make sure not to consume any more about 6 hours before going to bed.

Contrary to the side effects, which actually mainly occur in people who are already overexposed or who consume too much, caffeine naturally also has many health benefits, which we explain in our article on positive caffeine properties .

We hope this post was helpful and you can now make better decisions about whether, how much and what type of caffeine you consume.

Guayusa tea

Organic Guayusa from GUYA is original Guayusa from Ecuador. You can order our Guayusa directly from our shop and have it delivered to your home.

GUYA is Europe's first and largest Guayusa brand that offers you a large selection of Guayusa products. Our versatile Guayusa blends bring variety to your everyday life, keep you awake, focused and relaxed at the same time.

Since 2016 we have been working directly with farmers from Ecuador without intermediaries and have learned a lot about the processing of guayusa.

We look forward to your Guayusa order. 

Powder Guayusa

Buy pure guayusa tea powder. Our Guayusa powder offers you a variety of preparations without losing the organic quality.

Our PURE Guayusa Powder is original Guayusa, but particularly finely sieved to extract the powder particles . You can use the Guayusa powder in preparation of  a latte, cappuccino, espresso or for smoothies and pastries.

With the use of our Dripper , Guayusa powder can easily be used to prepare tea. The dripper's has a double-walled sieve that prevents the powder particles from getting into your tea. This way you can enjoy a delicious Guayusa tea without tea leaves in the water.


The Guayusa sets contain all our Guayusa tea flavours  as well as our tea accessories.Purchasing Guayusa in Sets is a best way to save money because  the Guayusa is in cheaper price in Sets than when sold as an individual product.

Our Guayusa comes from Ecuador and is organically grown there and traded fairly by us.

Each Guayusa set is put together differently and offers you a cheap alternative to expensive individual orders. Choose from sets with a teapot, tea glass, thermos flask, tea strainer and our 7 Guayusa varieties.


Our high-quality tea accessories made from stainless steel and special borosilicate glass have a long service life and can withstand all temperatures unconditionally! Find the right tea accessory for you in our online shop!

The glass products, as well as our stainless steel tea strainers, are suitable for any loose tea. All products can easily be cleaned in the dishwasher or under running water.

You can buy our products individually or in a combined package at a lower price.

Our tea accessories online shop also offers you a large selection of Guayusa tea which all together, as a set, make   an excellent gift.

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