An Overview of Caffeine Allergy

Symptoms, Causes, Diagnosis, and Treatment

Iced coffee with milk

Verywell / Zorica Lakonic 

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Many people depend on caffeine to get them going every day. But that can be a bad idea for people with a caffeine allergy or intolerance.

Most people can drink caffeinated coffee, tea, or soda without issue. Others may experience:

  • Diarrhea
  • Jitteriness
  • Insomnia
  • Other symptoms

Heavy consumption—more than 400 milligrams (mg) of caffeine, or four cups of coffee per day—can do this to anyone.

For some, though, it can happen after just one cup of java. That's about 95 mg of caffeine.

Negative reactions to modest amounts of caffeine may be due to a non-allergic food intolerance or, less often, an allergic reaction.

In this article, you'll learn the difference between a caffeine allergy and an intolerance, how they're diagnosed and treated, and some information to help you live with an allergy or intolerance.

You'll also learn about common coffee molds, which could be the cause of your allergic reaction.

Caffeine Allergy vs. Intolerance

It may be hard—both for you and your healthcare provider—to immediately identify caffeine as the source of your symptoms.

Beyond that, deciding whether it's a food allergy or intolerance can be difficult. Some important nuances may help you tell the difference.

Caffeine Allergy
  • Immune system reaction with IgE antibody

  • Skin rash, itching, hives

  • In extreme cases, anaphylaxis can develop

Caffeine Intolerance
  • Overly sensitive to caffeine's effects of suppressing adenosine and stimulating adrenaline

  • Jitteriness, insomnia, stomach upset

  • Can be distressing but is rarely serious

Caffeine Allergy

A caffeine allergy develops when the immune system incorrectly identifies caffeine as a harmful substance. It then releases an antibody called immunoglobulin E (IgE) into the bloodstream.

The body then responds with:

Skin rashes are perhaps the main differentiating feature between a caffeine intolerance and a caffeine allergy. Other symptoms include:

  • Anxiety
  • Chest pain
  • Cold sweats
  • Dizziness
  • Fatigue
  • Headaches
  • Heart palpitations
  • Joint pain
  • Muscles aches

Unlike with some allergies, respiratory symptoms are uncommon.

Food intolerance and caffeine allergies can manifest with symptoms in anywhere from a few minutes to two hours.

However, with a caffeine allergy, the severity of symptoms is typically linked to how fast they develop.

Those that develop quickly may, in rare cases, progress to a potentially life-threatening allergic reaction known as anaphylaxis.

Symptoms of Anaphylaxis

Call 911 or get emergency medical help if symptoms develop rapidly and you have:

  • Hives
  • Fever
  • Difficulty breathing
  • Facial swelling
  • Rapid heart rate
  • Vomiting

If left untreated, anaphylaxis can progress rapidly and lead to shock, coma, cardiac or respiratory failure, and death.

Mold on Coffee Beans

It is also possible that certain fungi on processed coffee or tea leaves may trigger an allergic response unrelated to caffeine.

Many of these fungi produce spores that the body recognizes as biological threats, particularly if you have an existing mold allergy.

Some molds also produce toxins called "mycotoxins," such as ochratoxin A, a common food contaminant.

In large amounts, OTA may be harmful to your health. Thus far, though, most of the evidence of harm has been in animal studies. Experts don't yet know what effect it has on human health.

Mold and Brand Battles

Some coffee companies have touted "mold-free" coffee beans and denigrated other brands. Other coffee makers have countered that they perform thorough checks of their product to keep mold levels well below the danger zone.

In animals, OTA is believed to harm the liver, kidneys, immune system, brain, and nervous system. It's also been tied to cancer and birth defects.

However, even if OTA can have these effects in humans, several studies show that the amount most Americans consume isn't a cause for concern.

In a 2017 study, researchers tested products from grocery stores in the U.S. over a two-year period. They found that most foods and beverages had no detectable OTA. The highest levels were in:

  • Dried fruits
  • Breakfast cereals
  • Infant cereals
  • Cocoa

Even from these foods, though, they concluded that the risk is negligible.

Mitchell, et al.

Current OTA concentrations are not high enough to elicit toxic effects, even at the mean consumption levels of the consumers who eat high amounts of the foods that may contain OTA.

— Mitchell, et al.

That's well and good for most people, but if you have a mold allergy, you may still react to small amounts of OTA and other mycotoxins.

If you react to coffee or tea (which also may contain these molds) but not to other sources of caffeine, ask your healthcare provider about testing for a mold allergy.

Because mycotoxins can also grow on nuts, grains, and other crops, you may need to limit the amount of these foods you consume.

If you're concerned about mycotoxins in coffee, buy high-quality, USDA-certified organic coffees, as they may have lower levels.


Caffeine may cause an allergy or intolerance. Allergies cause an immune response involving IgE antibodies and rashes as a primary symptom. Respiratory symptoms are rare. You may also be allergic to a common mold that's sometimes found in coffee and other crops.

Caffeine Intolerance

Food intolerance—also known as non-allergic food sensitivity—involves problems digesting certain foods rather than an allergy to them. While potentially distressing, a food intolerance is rarely serious.

An intolerance is often caused by the lack of a specific enzyme needed to metabolize a specific nutrient (like lactose). When your body can't break down the food properly, you end up with symptoms such as:

  • Bloating
  • Diarrhea
  • Gas
  • Spasms
  • Stomach aches

A caffeine intolerance is often caused by its effect on the endocrine (hormone) system.

Caffeine suppresses a chemical called adenosine, which helps you sleep, and increases the production of adrenaline, which gives you a burst of energy.

When your body doesn't process caffeine properly, it can have a magnified effect. That leads to too much adrenaline and symptoms including:

  • Jitteriness
  • Insomnia
  • Lightheadedness
  • Facial flushing
  • Rapid heartbeat
  • Rapid breathing
  • Profuse sweating
  • Stomach upset


A caffeine intolerance doesn't involve the immune system. Instead, it's a problem with digestion that magnifies the effect of caffeine on your endocrine system. That leads to too much adrenaline and symptoms like jitteriness and insomnia.


Caffeine allergies and intolerances are difficult to diagnose by symptoms alone. Even if you have a rash or hives, you may allergy testing to see if the allergen is caffeine or some other ingredient.

With coffee, it's even possible that certain types of beans or roasting techniques may be more problematic than others.

Allergy skin testing and IgE antibody blood tests are the fastest and most effective means to diagnose a caffeine allergy.

Less commonly, genetic testing may be used to identify mutations in the ADORA2A gene. Positive tests point to a caffeine allergy, while negative tests suggest an intolerance.


The main treatment for a caffeine allergy or intolerance is cutting it out of your diet.

If you suspect caffeine is the problem, it's reasonable to stop consuming it and see if the symptoms go away. You can find caffeine in:

  • Black, green, and white tea (but not herbal or rooibos/red tea)
  • Colas
  • Chocolate (cocoa or cacao)
  • Energy drinks
  • Certain headache medications (like Anacin)
  • Over-the-counter stimulants (like NoDoz)

Even a product labeled "decaffeinated" may contain trace amounts of caffeine that can stimulate the central nervous system in people who are especially sensitive.

Other Treatment Options

If allergy symptoms develop, an over-the-counter oral antihistamine can often help. Chronic or recurrent allergies may benefit from allergy shots used to desensitize you to the allergen.


Your healthcare provider can do allergy tests to see if you're allergic to caffeine. If not, an intolerance may be responsible for your symptoms. The primary treatment is avoiding caffeine. You may also benefit from allergy medications or shots.


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. They 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.

Another Hot Drink

If coffee is part of your morning ritual, replace it with a hot, non-caffeinated beverage. Don't drink decaf coffee—it contains between 2 milligrams (mg) and 15 mg in an 8-ounce cup.

Better options include:

  • Herbal tea
  • Warm apple cider
  • Hot water with lemon

You might also want to try a caffeine-free product called Teeccino. It's made of roasted chicory and designed to taste like coffee.

Drink More Water

Drinking plenty of water throughout the day can reduce your craving for cola or caffeinated energy drinks.

If you're used to cola, switch to sparkling water, which can keep you well hydrated without excess sugar.

Get Some Exercise

Take a long walk or exercise to counteract fatigue. Fresh air may give you a much-needed boost when your energy starts to lag, as well.

Even a 20-minute workout can get your heart pumping and stimulate the production of endorphins to help elevate your mood and alertness.

Take Time to "Crash"

If you're used to drinking a lot of caffeine, taking away the stimulant may cause you to "crash" for a couple of days.

You can prepare for this by setting aside time for extra sleep and relaxation.


While neither is common, it's possible to have a caffeine allergy or intolerance. Allergies involve an immune-system response while intolerances are caused by digestive problems.

Allergy symptoms can include an itchy rash, hives, anxiety, dizziness, and headaches. Intolerance symptoms may be bloating, diarrhea, jitteriness, and rapid heartbeat.

Your healthcare provider can test you for a caffeine allergy. If it's negative, an intolerance may be to blame.

The main treatment for either condition is avoiding caffeine. You may also benefit from allergy medications or shots.

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

A Word From Verywell

When used in moderation, the effects of caffeine—such as increased alertness—are often beneficial. But if you're one of the rare people with a caffeine allergy or intolerance, it can have really unpleasant effects.

Having to give up your favorite beverage is tough. But avoiding the offending substance can make you feel a lot better.

Food Allergies Healthcare Provider Discussion Guide

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

Doctor Discussion Guide Man

Frequently Asked Questions

  • Can you become desensitized to caffeine?

    Yes. People who drink caffeine regularly build up at least a partial tolerance to the effects of caffeine. According to researchers, blood pressure may not increase when regular caffeine users consume it, but their nervous system may still be affected.

  • How much caffeine is too much?

    According to the FDA, 400 milligrams a day of caffeine is a safe amount. That’s equal to about four cups of coffee. However, how much is too much depends on weight, tolerance, age, and whether or not you're sensitive to it. 

  • Can caffeine help with allergies?

    Caffeine may help you manage side effects of allergy medication, which can make you sleepy. Caffeine also has anti-inflammatory properties. Research has also shown it to have antiallergic effects.

19 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.