Side Effects of Caffeine and Caffeinated Drinks

Coffee for three
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Caffeine is so common in American society, you can easily forget that it is an addictive drug. Office workers are particularly prone to habitual coffee drinking, as it helps to keep you alert and ward off fatigue. Some people even think caffeine improves their memory, although the research evidence for this is mixed.

Short-Term Side Effects of Caffeine

There certainly are recognized side effects of caffeine. Side effects of caffeine intoxication are included in the Diagnostic and Statistical Manual of Mental Disorders (DSM 5), the gold standard for diagnosing mental health problems.

  • Diuresis – another embarrassing side effect of too much caffeine, you can end up running to the bathroom and urinating more fluid than you consumed.
  • Excitement – although excitement is often a positive experience, after too much caffeine, you can get overly excited about trivial events, which can be awkward in social situations.
  • Flushed face – a red face at work might make you look embarrassed, and can be embarrassing.
  • 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. Caffeine has also been found to help alleviate migraine pain in the right doses. 
  • Insomnia – this can manifest in many different ways, but overall, it adds up to having difficulty getting enough sleep.
  • Muscle twitching – involuntary muscle twitches are an annoying side effect of caffeine for some people, but there are other causes, so try abstaining from caffeine if this is an ongoing problem for you, and see if the twitching subsides. If it does not, talk to your doctor about treatment for this common problem.
  • Nervousness – this is a sense of mental uneasiness, a kind of restlessness of the mind, that often goes hand in hand with anxiety.
  • 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 can run yourself down, and 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 fretfulness that makes it difficult to calm your body.
  • Rambling flow of thought and speech – this is a common side effect of stimulant drugs and is often more annoying to the listener than to the speaker. But be aware that getting over-stimulated on coffee and dominating conversations might undermine your popularity at work.
  • Restlessness – this is basically difficulty relaxing and calming 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.

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Article Sources
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  1. 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

  2. Juliano LM, Evatt DP, Richards BD, Griffiths RR. Characterization of individuals seeking treatment for caffeine dependencePsychology of Addictive Behaviors. 2012;26(4):948-954. doi:10.1037/a0027246

  3. Lee MJ, Choi HA, Choi H, Chung C-S. Caffeine discontinuation improves acute migraine treatment: a prospective clinic-based studyJ Headache Pain. 2016;17(1):71. doi:10.1186/s10194-016-0662-5

  4. Cornelis MC. The impact of caffeine and coffee on human health. Nutrients. 2019;11(2) doi:10.3390/nu11020416

Additional Reading
  • Farag, N., Whitsett, T., McKey, B., Wilson, M., Vincent, A., Everson-Rose, S., and Lovallo, W. "Caffeine and Blood Pressure Response: Sex, Age, and Hormonal Status,"​ Journal of Women's Health 19:1171-1176. 2010.

  • American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, (DSM 5), American Psychiatric Association. 2013.
  • Derbyshire, E. & Abdula, S. "Habitual Caffeine Intake in Women of Childbearing Age," J Hum Nutr Diet 21:159–164. 2008.