Addiction Addictive Behaviors Caffeine Side Effects of Caffeine By Elizabeth Hartney, BSc, MSc, MA, PhD Elizabeth Hartney, BSc, MSc, MA, PhD Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada. Learn about our editorial process Updated on March 04, 2021 Medically reviewed Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by John C. Umhau, MD, MPH, CPE Medically reviewed by John C. Umhau, MD, MPH, CPE John C. Umhau, MD, MPH, CPE is board-certified in addiction medicine and preventative medicine. He is the medical director at Alcohol Recovery Medicine. For over 20 years Dr. Umhau was a senior clinical investigator at the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health (NIH). Learn about our Medical Review Board Print Alicia Llop / Getty Images Caffeine is so common in American society, you can easily forget that it is an addictive drug. People consume caffeine not only in coffee, but also in tea, chocolate, and energy drinks. The latter may have much more caffeine than coffee. While it may have some benefits, it is important to remember that you may experience a number of troublesome caffeine side effects as well. Positive Effects of Caffeine Caffeine is a natural stimulant found in a number of different plant sources, most notably coffee beans, cacao seeds, and tea leaves. Because it stimulates the central nervous system (CNS), people often consume caffeine—often in the form of coffee, tea, or energy drinks—to combat tiredness and improve attention. In addition to helping people feel more awake, research suggests that caffeine may have a number of other health benefits. These include: Better memory: Some research has found that consuming caffeine may enhance memory consolidation and thus boost long-term memory. Improved mood: Research has found that caffeine can have a positive effect on mood. In one study, a dose of caffeine roughly equivalent to the amount found in a single soda was associated with improvements in performance and subjective mood. Increased metabolism: Studies have found that caffeine consumption can lead to increases in metabolism and may be helpful for weight maintenance. Reduced mortality: One study found that consuming two to four cups of coffee per day was associated with a decreased risk of death. Caffeine has also been found to help alleviate migraine pain in the right doses. Caffeine: Everything You’ve Been Afraid to Ask Caffeine Side Effects There are a number of short-term side effects that people may experience when consuming caffeine. These side effects typically occur when larger amounts of caffeine are consumed, often more than 400 milligrams (mg), or more than four to five cups of coffee, per day. This can vary, however, depending on the individual and the amount of caffeine that they typically consume in a day. According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), the tool that doctors and mental health professionals use to diagnose psychological conditions, some of the major short-term side effects of caffeine intoxication are: Anxiety: Caffeine can make you feel more alert, but too much can also lead to feelings of anxiety and nervousness. Because caffeine can trigger your body's fight-or-flight response, you may be left feeling like you are high alert. Caffeine-induced anxiety disorder is a caffeine-related condition described in the DSM-5. Diuresis: Caffeine has a stimulating effect on the bladder so it may increase the frequency and urgency of urination. One study found that consuming large quantities of caffeine (more than 450 mg per day) may increase the risk of urinary incontinence. Flushed face: Because caffeine causes blood vessels to dilate, it can lead to flushing of the face and other areas of the body. Gastrointestinal disturbance: There is a range of gastrointestinal disturbances that can be side effects of too much caffeine, including stomachache, gas, heartburn, constipation, diarrhea, nausea, and vomiting. However, while stomachaches are quite common after a lot of coffee, vomiting is quite rare, and if you have this reaction, you should avoid caffeine completely until you have discussed this with your doctor. Headache: Caffeine is one of the most common causes of headache. It can trigger a headache when taken in excess, and if you drastically cut it out, it can cause a caffeine withdrawal headache. Insomnia: People often consume caffeine to increase wakefulness, but this effect can also sometimes interfere with sleep. In some cases, people may have trouble falling asleep or may have a difficult time getting restful, restorative sleep. Caffeine may stay in your system for around five hours, so it is a good idea to stop consuming caffeine by early afternoon. Muscle twitching: Involuntary muscle twitches can be a side effect of caffeine for some people. However, there are other causes. If this is an ongoing problem for you, try abstaining from caffeine to see if the twitching subsides. If it does not, talk to your doctor about treatment. Periods of inexhaustibility: Although this side effect may seem desirable, we all need rest. If you are unable to tire enough to get adequate rest, you may not give your body adequate time to repair itself. You may not feel exhausted, but your body will become worn out without regular breaks from activity. Psychomotor agitation: This is a kind of physical stimulation that makes it difficult to calm your body. Rambling flow of thought and speech: This is a common side effect of stimulant drugs and can make conversation and communication more difficult. Restlessness: After consuming caffeine, you may also find that it is difficult to relax or calm yourself down. Tachycardia or cardiac arrhythmia: These side effects are changes to the speed and regularity of your heartbeat and are certainly a cause for concern. Stop using caffeine and see your doctor if you think your heartbeat is abnormal, particularly if you feel it is excessively rapid or irregular. Research has shown that many people are unaware of these side effects, and a good deal of the research into caffeine has lauded the positive short-term effects, such as increased attention and energy, without taking these health effects into account. Caffeine During Pregnancy Excessive caffeine consumption during pregnancy may lead to adverse side effects. Research suggests that daily amounts over 200 mg may increase the risk of miscarriage. Some research suggests that caffeine use during pregnancy may contribute to low birth weight. Effects of Caffeine on the Body Long-Term Side Effects of Caffeine Caffeine use or overuse may also have some long-term side effects. These can include: Caffeine Dependence Because this substance can be habit-forming, you may also become both physically and psychologically dependent on it. This means that if you go for a long period without any caffeine, you may begin to experience symptoms of withdrawal. Caffeine Withdrawal Another common long-term side effect is the experience of withdrawal symptoms. People who consume large amounts of caffeine more frequently may be more likely to feel withdrawal symptoms when they go several hours without a dose of caffeine. Symptoms of caffeine withdrawal can include: Low moodHeadacheNauseaMental fogginessLightheadedness Research has found that people who consume caffeine daily have a higher risk of experiencing withdrawal symptoms such as fatigue and headaches. A Word From Verywell When consumed in moderation, caffeine is not harmful and can even have some benefits. However, individual responses may vary. If you are sensitive to the effects of caffeine, you may find that you want to gradually reduce your caffeine intake. You will eventually find that the unpleasant caffeine side effects you were experiencing lessen or disappear altogether. Remember that coffee isn't the only source of caffeine. If you are trying to watch your intake, you should also be aware that many foods, beverages, and supplements may also contain caffeine. Milk chocolate, dark chocolate, hot chocolate, tea, iced tea, soft drinks, energy drinks, and even decaffeinated coffee also contain varying amounts of caffeine. Can You Overdose on Caffeine? Was this page helpful? Thanks for your feedback! Learn the best ways to manage stress and negativity in your life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 12 Sources Verywell Mind 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. Borota D, Murray E, Keceli G, et al. Post-study caffeine administration enhances memory consolidation in humans. Nat Neurosci. 2014;17(2):201-203. doi:10.1038/nn.3623 Lieberman HR, Wurtman RJ, Emde GG, Roberts C, Coviella IL. The effects of low doses of caffeine on human performance and mood. Psychopharmacology (Berl). 1987;92(3):308-12. doi: 10.1007/BF00210835. PMID: 3114783. Harpaz E, Tamir S, Weinstein A, Weinstein Y. The effect of caffeine on energy balance. J Basic Clin Physiol Pharmacol. 2017;28(1):1-10. doi: 10.1515/jbcpp-2016-0090 Kim Y, Je Y, Giovannucci E. Coffee consumption and all-cause and cause-specific mortality: a meta-analysis by potential modifiers. Eur J Epidemiol. 2019;34(8):731-752. doi: 10.1007/s10654-019-00524-3 Lee MJ, Choi HA, Choi H, Chung C-S. Caffeine discontinuation improves acute migraine treatment: a prospective clinic-based study. J Headache Pain. 2016;17(1):71. doi:10.1186/s10194-016-0662-5 Meredith SE, Juliano LM, Hughes JR, Griffiths RR. Caffeine use disorder: a comprehensive review and research agenda. J Caffeine Res. 2013;3(3):114-130. doi: 10.1089/jcr.2013.0016 Jura YH, Townsend MK, Curhan GC, Resnick NM, Grodstein F. Caffeine intake, and the risk of stress, urgency and mixed urinary incontinence. J Urol. 2011;185(5):1775-1780. doi:10.1016/j.juro.2011.01.003 Juliano LM, Evatt DP, Richards BD, Griffiths RR. Characterization of individuals seeking treatment for caffeine dependence. Psychology of Addictive Behaviors. 2012;26(4):948-954. doi:10.1037/a0027246 Cornelis MC. The impact of caffeine and coffee on human health. Nutrients. 2019;11(2) doi:10.3390/nu11020416 Weng X, Odouli R, Li DK. Maternal caffeine consumption during pregnancy and the risk of miscarriage: a prospective cohort study. Am J Obstet Gynecol. 2008;198(3):279.e1-8. doi: 10.1016/j.ajog.2007.10.803 Rhee J, Kim R, Kim Y, et al. Maternal caffeine consumption during pregnancy and risk of low birth weight: a dose-response meta-analysis of observational studies. PLoS One. 2015;10(7):e0132334. doi:10.1371/journal.pone.0132334 Juliano LM, Huntley ED, Harrell PT, Westerman AT. Development of the caffeine withdrawal symptom questionnaire: caffeine withdrawal symptoms cluster into 7 factors. Drug Alcohol Depend. 2012 Aug 1;124(3):229-34. doi: 10.1016/j.drugalcdep.2012.01.009 Additional Reading American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, (DSM 5); 2013. Get Treatment for Addiction Advertiser Disclosure × The offers that appear in this table are from partnerships from which Verywell Mind receives compensation.