Allergies Food Allergies Symptoms An Overview of Caffeine Sensitivity Symptoms, Causes, Diagnosis, and Treatment By Daniel More, MD Updated on April 11, 2024 Medically reviewed by Jurairat J. Molina, MD Print Verywell / Zorica Lakonic Table of Contents View All Table of Contents Sensitivity vs. Allergy Causes of Caffeine Sensitivity Diagnosis Treatment Coping Caffeine intolerance symptoms can occur when you experience an overreaction to coffee and other caffeinated beverages or foods. With caffeine sensitivity, the adverse symptoms after consuming caffeine include headaches, jittery feelings, diarrhea, and insomnia. These symptoms can occur when anyone drinks too much coffee, but caffeine sensitivity is a heightened 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 determine 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, the body's response to these chemicals is amplified, causing symptoms such as: Jitteriness or shakiness Headaches Heart palpitations (skipped beats) Diarrhea and other digestive disorders Insomnia and/or fatigue Anxiety Irritability and restlessness Urinary urgency (needing to rush to the bathroom to pee) Does Genetics Play a Role? Caffeine sensitivity may be linked to the CYP1A2 enzyme, which accounts for about 95% of all caffeine metabolism in the human body. Genetic research suggests at least 13 variations that could influence the CYP1A2 gene and its role (how fast you metabolize caffeine, for example). More study is needed to fully understand the role of genes. Genetic Predisposition: What It Is, What It Means for You 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, nasal congestion, swelling at the mouth or face, and a skin rash or hives. Rarely, a caffeine allergy requires immediate care for a potentially life-threatening, whole-body allergy known as anaphylaxis. 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 rashFeverDifficulty breathingWheezingFacial swellingRapid heart rateVomitingSudden, severe diarrheaA feeling of impending doom Causes of Caffeine Sensitivity People's level of sensitivity to caffeine are to caffeine may be due to genetics, at least in part. One study of the CYP1A2 enzyme responsible for caffeine metabolism found a genetic link to explain why 54% of people studied were slower at processing caffeine in their bodies, while about 46% were fast metabolizers. But many other factors can affect your caffeine sensitivity, too. They include: Your age and sex Hormone activity Liver disease Obesity Smoking Diet Caffeine also interacts with many medications. Methotrexate, a drug used to treat rheumatoid arthritis, may be affected by caffeine intake, though some studies suggest a benefit when using both. Caffeine also may be included in a drug, as is the case with the pain reliever Excedrin. Diagnosis Caffeine sensitivity is hard to pinpoint because its immune mechanisms are poorly understood. To reach a diagnosis, a healthcare provider would need to exclude all other possible causes, most especially caffeine allergy. If you are suddenly sensitive to caffeine, your symptoms may be due to 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. To this end, your 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. Treatment 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 teaColas and energy drinksChocolate, cocoa, or cacaoCertain headache medications (like Anacin)Over-the-counter stimulants (like NoDoz) According to the Food and Drug Administration (FDA), up to 400 milligrams (mg) 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. 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 rather than cutting out all caffeine. Often, older people become more sensitive to certain effects of caffeine; one reason may be the slower metabolic clearance time for caffeine. The liver takes longer to break down caffeine, leaving more of it to build up in the body for longer periods. Medications also can affect this process. 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. Caffeine in Other Products An 8-ounce cup of coffee contains about 80 mg to 100 mg of caffeine. By comparison, a 12-ounce can of a caffeinated soft drink typically contains 30 mg to 40 mg and an 8-ounce cup of green or black tea has 30 mg to 50 mg. Energy drinks can deliver up to 250 mg of caffeine per 8 fluid ounces. Switching From Coffee to Caffeine Pills: Is It Worth It? Coping 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. Herbal Tea. graphicmeditation@gmail.com/GettyImages 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 teaWarm apple ciderHot water with lemonCaffeine-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. How to Deal With Caffeine Withdrawal Summary Caffeine sensitivity occurs 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. Download PDF Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Email Address Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. 12 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. dePaula J, Farah A. Caffeine consumption through coffee: content in the beverage, metabolism, health benefits and risks. Beverages. 2019;5(2):37. doi:10.3390/beverages5020037 Turnbull JL, Adams HN, Gorard DA. Review article: the diagnosis and management of food allergy and food intolerances. Aliment Pharmacol Ther. 2015;41(1):3-25. doi:10.1111/apt.12984 Mullins VA, Bresette W, Johnstone L, Hallmark B, Chilton FH. Genomics in Personalized Nutrition: Can You "Eat for Your Genes"? Nutrients. 2020 Oct 13;12(10):3118. doi:10.3390/nu12103118. Abrams EM, Sicherer SH. Diagnosis and management of food allergy. CMAJ. 2016;188(15):1087-93. doi.10.1503/cmaj.160124 Sugiyama K, Cho T, Tatewaki M, et al. Anaphylaxis due to caffeine. Asia Pac Allergy. 2015;5(1):55-6. doi:10.5415/apallergy.2015.5.1.55 Nehlig A. Interindividual Differences in Caffeine Metabolism and Factors Driving Caffeine Consumption. Pharmacol Rev. 2018 Apr;70(2):384-411. doi:10.1124/pr.117.014407. EL Nouby F, Fathi N, Fehr A, Assi A, Lotfy R, Goma S. Does caffeine reduce methotrexate intolerance in patients with rheumatoid arthritis: a randomized controlled study. Egypt Rheumatol Rehabil. 2020 Oct;47(36). doi:10.1186/s43166-020-00028-z Willson C. The clinical toxicology of caffeine: a review and case study. Toxicol Rep. 2018;5:1140-1152. doi:10.1016/j.toxrep.2018.11.002 Kajita N, Miyama S, Kinoshita K, Yoshida K, Narita M. Green tea-induced anaphylaxis: The first pediatric case report. Allergol Int. 2021 Oct;70(4):507-508. doi:10.1016/j.alit.2021.05.007. Food and Drug Administration. Spilling the beans: how much caffeine is too much? UCLA Health. Caffeine sensitivity grows as people age. Cappelletti S, Piacentino D, Sani G, Aromatario M. Caffeine: cognitive and physical performance enhancer or psychoactive drug? Current Neuropharmacology. 13(1):71-88. doi:10.2174%2F1570159X13666141210215655 Additional Reading Landholt, H. No thanks, coffee keeps me awake: Individual caffeine sensitivity depends on ADORA2A Genotype. Sleep. 2012;35(7):899-900. doi:10.5665/sleep.1942 Tognetti L, Murdaca F, Fimiani M. Caffeine as a cause of urticaria-angioedema. Indian Dermatol Online J. 2014;5(6):113. doi:10.4103/2229-5178.146181 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 formerly practiced at Central Coast Allergy and Asthma in Salinas, California. 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