Caffeine Sensitivity | Allergy Test US

According to research, caffeine is a stimulant in the central nervous system boosting alertness and energy hence why you commonly see people flooding coffee shops in the morning. Caffeine sensitivity occurs when you experience an overreaction after consuming caffeinated beverages. These symptoms that you may suffer when you have caffeine sensitivity are the same for people who drink too much coffee. However, since caffeine sensitivity is quite different, it only requires you to drink a little coffee or caffeinated beverages for these symptoms to occur. A small quantity of caffeine will trigger caffeine sensitivity symptoms. Caffeine is a naturally occurring substance in plants like tea leaves, coffee beans, cocoa beans, kola nuts, and other substances.

Caffeine sensitivity, even though abnormal, isn’t the same as caffeine allergy. Caffeine allergy involves the immune system. There are varying degrees of caffeine sensitivity. Some people can have two shots of espresso without any caffeine sensitivity symptoms. Others may experience insomnia for hours after a small glass of a caffeinated energy drink. Caffeine sensitivity fluctuates daily based on multiple factors. There are three groups of caffeine sensitivity:

Hypersensitivity: People with an extreme sensitivity to caffeine can’t tolerate even the most minuscule amounts without experiencing negative symptoms.

Hyposensitivity: According to a study, around 10% of the population has a gene linked to higher caffeine intake. These people can have considerable amounts of caffeine in the evening and not experience side effects like insomnia.

Normal sensitivity: Most people have normal caffeine sensitivity, where they can take upto 400 milligrams of coffee daily without getting any side effects.

Caffeine energizes the body by mimicking a substance called adenosine, increasing your wakefulness. Through this process, dopamine is triggered, releasing adrenaline which gives you an energy jolt. Caffeine has small molecules which can easily pass through the membranes of the digestive tract. So, from your first sip, the caffeine in your drink makes its way to your bloodstream, energizing you instantly. That’s why it boosts energy when you need a “pick me up” in the afternoon. Upon consuming caffeine, it will remain in your body for 5.7 hours, and that’s how long you should expect caffeine to stay active in your body feeling its effects.

Symptoms of caffeine sensitivity

Caffeine sensitivity means that you’ll feel its effects more strongly than those with normal sensitivity. The most common caffeine sensitivity symptoms include:

  • Headache
  • Jitters
  • Anxiousness
  • Racing heartbeat
  • Insomnia
  • Restlessness

Causes of caffeine sensitivity

While some people are sensitive to the anxiety-promoting effects of caffeine, others are sensitive to caffeine-induced insomnia {1}. People suffering from panic or anxiety disorder may experience worse symptoms upon consuming caffeine. Some researchers believe that caffeine sensitivity occurs at receptor or metabolism levels. This means that while some people experience caffeine sensitivity because their bodies take longer to metabolize it, others are more sensitive to the long-term effects of caffeine. Usually, upon caffeine consumption, there is a temporary rise in blood pressure, which disappears upon regular consumption. However, people with caffeine sensitivity can experience elevated blood pressure every time they consume caffeine.

Several factors differentiate caffeine sensitivity from one person to the next. Certain factors affect one’s consumption, which can result in increased caffeine sensitivity. Factors like older age, genetics, and the medications you’re on can alter your sensitivity to caffeine, increasing it and worsening your symptoms. Some instances, like pregnancy, also require one to avoid caffeine, and so should adolescents and children, as it causes issues in their development. The risk factors that cause more caffeine sensitivity include:

  • Older age
  • Genetics
  • Pregnant women
  • Children and adolescents
  • Medications

Older age

Older adults can suffer caffeine sensitivity more than others, as it will affect their sleep. Older adults are always more sensitive to the insomnia effects of caffeine. Even though there is no difference in metabolism between different ages, there are alterations to adenosine receptors which cause worse sleep indicators. By targeting your adenosine receptors, caffeine affects sleep regulation, arousal, effects of caffeine on sleep, and your sleep-wake cycle.

Genetics (brain chemistry and liver metabolism)

The human brain consists of over 100 billion neurons that transmit instructions within the brain and nervous system. To do their job, neurons need the help of neurotransmitters. Neurotransmitters act as messengers between neurons and fire billions of times within a day following your biological response, thoughts, and movement. The more active your brain is, the more adenosine it produces. As your adenosine levels build up, you become more and more tired. Consuming caffeine blocks your adenosine receptors in the brain, preventing you from realizing it when you’re tired. Caffeine also affects the neurotransmitters burning about a “feel good” effect. According to studies, some people with caffeine sensitivity have an exaggerated reaction to this process because of a variation in their ADORA2A gene. People with this gene variation feel caffeine effects more intensely and for longer than those with normal sensitivity to caffeine.

Genetics highly affects how the liver metabolizes caffeine. Those with caffeine sensitivity produce fewer CYP1A2 enzymes {2}. This enzyme plays a massive role in how quickly liver your liver metabolizes caffeine. People suffering from caffeine sensitivity take longer to process and expel caffeine from their systems. Due to this, the impact of caffeine on their bodies tends to be more intense and lasts longer.

Pregnant women

Most experts agree that it’s okay for pregnant women to consume less than 200mg of caffeine daily. During pregnancy, caffeine travels through the placenta to the developing fetus, which can’t eliminate caffeine and depends on the mother’s kidneys. However, pregnancy can make it hard for a woman’s kidneys to clear caffeine. Because of this, pregnant women need to be aware of consuming caffeine. High amounts of caffeine can affect the developing fetus by causing the constriction of blood vessels supplying the placenta and, in turn, increasing fetal heartbeat. This can hinder the oxygen supply to the fetus.

Children and adolescents

Even though there are companies that create caffeinated drinks for children, it’s not a good idea. Caffeine can impact the neurological and cardiovascular systems of children and adolescents. These groups can also develop a dependence on caffeine. It is also possible for these groups to consume higher doses of caffeine as they need help understanding the difference between sports and energy drinks. While energy drinks contain electrolytes, sports drinks may result in the consumption of large quantities of caffeine.


Some supplements and medications can interact with caffeine in specific ways, making you more sensitive to it and causing severe symptoms. Examples of these medications are theophylline (used by asthma patients) and echinacea (a herbal supplement relieving cold symptoms). You should consult a doctor if your medications somehow mess up your caffeine sensitivity.

Other factors that can increase caffeine sensitivity risk include:

  • Female sex
  • Certain chronic health conditions
  • Smoking
  • Oral contraceptive (birth control) use

Caffeine sensitivity testing

Our Intolerance Test

If you’ve been having some of the caffeine sensitivity symptoms mentioned above every time you consume coffee, talk to your doctor so they can take tests to check for any underlying illnesses that could be causing you to be more sensitive to caffeine. If you find none to be the issue, you can order a caffeine Intolerance Test. This test will check for all common food and drink intolerances, including caffeine. You will then get your results within seven days after sending your sample back to the lab. An intolerance or sensitivity test helps you determine what’s in your food causing specific unbreakable symptoms so you can cut the food item out of your diet. If the results show that you have a caffeine intolerance, avoiding any foods or drinks with caffeine is best to avoid caffeine sensitivity symptoms.

While caffeine helps boost energy and mood, it can be problematic if it causes caffeine sensitivity symptoms. You can manage these symptoms by reducing caffeine consumption or altogether avoiding it if you’re hypersensitive. No matter your sensitivity to caffeine, if it somehow affects your life, you should avoid it. You can slowly decrease caffeine consumption until you’re comfortable or can function without it.


  1. Yang, A., Palmer, A. A., & de Wit, H. (2010). Genetics of caffeine consumption and responses to caffeine. Psychopharmacology, 211(3), 245–257.
  2. Tian, D. D., Natesan, S., White, J. R., & Paine, M. F. (2019). Effects of common CYP 1A2 genotypes and other key factors on intraindividual variation in the caffeine metabolic ratio: An exploratory analysis. Clinical and translational science, 12(1), 39-46. (