An Overview of Caffeine Sensitivity

Symptoms, Causes, Diagnosis, and Treatment

Iced coffee with milk

Verywell / Zorica Lakonic 

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Caffeine sensitivity is when you experience an overreaction to coffee and other caffeinated beverages. With caffeine sensitivity, you will experience adverse symptoms after drinking caffeine, such as jitteriness, headaches, diarrhea, and insomnia.

Symptoms like these can occur to anyone when they drink too much coffee, but caffeine sensitivity is an abnormal response that occurs at typically smaller doses.

Caffeine sensitivity is not the same thing as caffeine allergy, which is caused by a specific immune response to caffeine. Even so, both share similar symptoms.

This article explains what caffeine sensitivity is and how it differs from a caffeine allergy. It also describes how caffeine sensitivity is diagnosed and how to cope if you are suddenly forced to quit caffeine.

Caffeine Sensitivity vs. Caffeine Allergy

It may be hard—both for you and your healthcare provider—to immediately identify caffeine as the source of your symptoms and whether caffeine sensitivity or caffeine allergy is involved. Some important nuances may help you tell the difference.

Caffeine Sensitivity
  • An abnormal immune response not involving IgE antibodies

  • Characterized by an overreaction to the effects of caffeine

  • Symptoms are rarely severe

  • Diagnosed by exclusion of other possible causes

  • Treated by avoiding caffeine

Caffeine Allergy
  • An abnormal immune response involving IgE antibodies

  • Characterized by symptoms common with all food allergies

  • Symptoms can be severe and, on rare occasions, life-threatening

  • Diagnosed with allergy tests

  • Treated by avoidance of caffeine as well as antihistamines

Caffeine Sensitivity

Caffeine sensitivity is a type of food sensitivity. And, although the term "food sensitivity" is sometimes used interchangeably with "food intolerance," they are not the same:

  • Food intolerance is due to the lack of digestive enzymes to process and break down foods (such as lactose in milk). This causes gastrointestinal symptoms such as bloating, gas, diarrhea, and stomach cramps.
  • Food sensitivities are caused by an abnormal immune response that can affect other organ systems beyond the gastrointestinal tract.

Caffeine works by suppressing a chemical called adenosine that helps you sleep, and by increasing the production of adrenaline, which gives you a burst of energy.

In people with caffeine sensitivity, your body's response to these chemicals is amplified, causing symptoms such as:

  • Jitteriness or shakiness
  • Headaches
  • Heart palpitations (skipped beats)
  • Diarrhea
  • Insomnia
  • Anxiety
  • Irritability
  • Urinary urgency (needing to rush to the bathroom to pee)

Does Genetics Play a Role?

Caffeine sensitivity is not well understood but is thought to be caused by an abnormal immune response unrelated to an allergy. Some research suggests that genetics play a part in why some people are overly sensitive to caffeine.

Caffeine Allergy

A caffeine allergy also involves an abnormal immune response but one that is specific. With allergies of any sort, the body will respond to an allergen (allergy-causing substance) by releasing an antibody called immunoglobulin E (IgE).

This, in turn, causes certain white blood cells to degranulate (break open) and release a chemical called histamine into the bloodstream. Histamine triggers an inflammatory response, causing blood vessels and tissues to swell and leak fluid, triggering symptoms of allergy.

Symptoms of caffeine allergy tend to develop quickly and may include:

  • Itching or tingling in the mouth
  • Sneezing or nasal congestion
  • Itchy, red eyes
  • Skin rash or hives with itching
  • Abdominal cramps or pain
  • Diarrhea
  • Swelling of the face, mouth, or throat
  • Difficulty breathing
  • Difficulty swallowing
  • Dizziness or lightheadedness

On rare occasions, a caffeine allergy can lead to a potentially life-threatening, whole-body allergy known as anaphylaxis. If left untreated, anaphylaxis can rapidly progress and lead to shock, coma, cardiac or respiratory failure, and death.

When to Call 911

Call 911 or rush to your nearest emergency room if you experience signs and symptoms of anaphylaxis, including:

  • Sudden, severe hives or rash
  • Fever
  • Difficulty breathing
  • Wheezing
  • Facial swelling
  • Rapid heart rate
  • Vomiting
  • Sudden, severe diarrhea
  • A feeling of impending doom


Caffeine sensitivity is hard to pinpoint because its immune mechanisms are poorly understood. To reach a diagnosis, the healthcare provider would need to exclude all other possible causes, most especially caffeine allergy.

To this end, your healthcare provider may perform allergy skin testing and IgE antibody blood tests to see if you have a caffeine allergy. If you do not and all other causes have been excluded, including food intolerances, then your provider may reasonably assume that food sensitivity is involved, particularly if the symptoms are not severe.


The main treatment for caffeine sensitivity is cutting all caffeine out of your diet. This may include beverages and foods like:

  • Black, green, and white tea
  • Colas and energy drinks
  • Chocolate, cocoa, or cacao
  • Certain headache medications (like Anacin)
  • Over-the-counter stimulants (like NoDoz)

With that said, you may be dose-sensitive, meaning that symptoms only occur at certain higher doses. In some cases, all you may need to do is cut back on caffeine. Some people even find differences in their response to dark-roasted coffee beans and light-roasted coffee beans.

If your symptoms are not serious, you can see how you respond to different forms of caffeine on a trial-and-error basis. Speak with your healthcare provider first just to be safe.


Quitting caffeine is easier said than done. Caffeine withdrawal can cause headaches, fatigue, and irritability. You may even experience nausea and flu-like symptoms. These symptoms typically start within 12 to 24 hours of stopping caffeine and can take between two and nine days to fully subside.

You can do several things to wean yourself off caffeine with the least amount of stress:

  • Rest: If you're used to drinking a lot of caffeine, stopping may cause you to "crash" for a couple of days. You can prepare for this by setting aside time for extra sleep and relaxation.
  • Drink water: Drinking plenty of water throughout the day can reduce your craving for cola or caffeinated energy drinks.
  • Exercise: Taking a long walk or exercising can counteract fatigue. Fresh air may give you a much-needed boost when your energy starts to lag.

Alternative Drinks for Caffeine Sensitivity

If coffee is part of your morning ritual, you can replace it with a hot, non-caffeinated beverage such as:

  • Herbal tea
  • Warm apple cider
  • Hot water with lemon
  • Caffeine-free roasted chicory coffee

Skip the Decaf

If you have caffeine sensitivity, don't drink decaffeinated coffee as it contains between 2 milligrams (mg) and 15 mg of caffeine per 8-ounce cup.


Caffeine sensitivity is when you are overly sensitive to the effects of caffeine, causing jitteriness, headaches, diarrhea, and other symptoms. Caffeine sensitivity is thought to be an immune-related condition that differs from caffeine allergy (which can be far more severe) and food intolerance (which is caused by a lack of digestive enzymes).

Caffeine sensitivity is diagnosed based on the exclusion of all other causes. The main treatment is the avoidance of caffeine.

Giving up caffeine can lead to withdrawal symptoms. You can ease them by replacing coffee with a non-caffeinated beverage, drinking lots of water, and getting ample rest and exercise.

A Word From Verywell

When used in moderation, the effects of caffeine—such as increased alertness—can be beneficial. But, if you're one of the rare people with caffeine sensitivity, you'll need to turn to other forms of stimulation to give yourself a boost.

One tried-and-true method is exercise. Something as simple as a brisk walk can spur the release of "feel-good" hormones called endorphins that not only amp up your energy levels but your mood as well. And, unlike a cup of coffee, the effects are absolutely free.

Food Allergies Healthcare Provider Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

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Frequently Asked Questions

  • What is caffeine sensitivity?

    Caffeine sensitivity is thought to be an immune-related response in which the body overreacts to the effects of caffeine. It is poorly understood but differs from caffeine allergy, which involves a specific antibody known as immunoglobulin E (IgE). For this reason, caffeine sensitivity is sometimes referred to as a form of non-IgE food sensitivity.

  • How much caffeine is too much?

    According to the Food and Drug Administration (FDA), up to 400 milligrams a day of caffeine is a safe amount. That’s equal to about 4 cups of coffee. However, your response to caffeine can vary based on your weight, age, and individual sensitivity to caffeine.

  • Does caffeine sensitivity change with age?

    Possibly. In the same way that some people with caffeine allergies become less reactive to caffeine as they get older, it is possible that you may become less sensitive to caffeine over time. Exposure to caffeine in tiny amounts may also desensitize you to the effects of caffeine (although this should not be done without an allergist if you have a caffeine allergy).

  • Why am I suddenly sensitive to caffeine?

    It may not be caffeine that you are sensitive to but other substances used in the making of the product. Some people find, for instance, that they are sensitive to dark-roasted coffee beans but not light-roasted beans. Others have a reaction to molds that can grow on coffee beans. Speak with your healthcare provider as sudden food sensitivities should never be ignored.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.