20+ Harmful Effects of Caffeine
The harmful effects of caffeine are sometimes harder to find information on than all of the reported positives.
Here are a few of the studies that concluded that caffeine could be potentially dangerous to one’s health.
Research Showing Harmful Effects of Caffeine
- More than 4 cups of coffee linked to an early death. A Mayo Clinic partnered study found that men who drank more than four 8 fl.oz. cups of coffee had a 21% increase in all-cause mortality. However, those that reported that they consumed excessive amounts of caffeine were also likely to smoke and have poor fitness. Dr. Nancy Snyderman from NBC said there were a few discrepancies with the study, but stresses that moderation is still key. See Her Interview Here. Another study showed that those who consume 6+ coffees per day have a greater risk of developing heart disease. Another study concluded that those that consume more than 6 cups of coffee daily are prone to poor health and possibly an earlier death and poor quality of life due to those diseases. Here’s the study’s summary.
- Caffeine consumption may raise blood pressure. Especially in those already suffering from hypertension and those who don’t normally consume caffeine. People with hypertension were given 250 mg of caffeine (about 2 coffees) and the data revealed that their blood pressure was elevated for about 2-3 hours after the caffeine. Src. A second study performed by The Mayo Clinic found similar results from a 160 mg dose. All participants experienced a marked rise in blood pressure and it was the most pronounced in those that didn’t normally consume caffeine. Src.
- Increased risk of heart attacks among young adults. A study conducted by Dr. Lucio Mos found that young adults who were diagnosed with mild hypertension had 4 times the risk of having a heart attack if they consumed the amount of caffeine equivalent to 4 cups of coffee. More moderate consumption showed 3 times the risk. Src.
- Caffeine linked to gout attacks. This study showed that people who binge on caffeinated beverages increase their risk for a gout flare-up. Src.
- Breast tissue cysts in women. One study showed that “Women who consumed 31–250 mg of caffeine/day had a 1.5-fold increase in the odds of developing fibrocystic breast disease and women who drank over 500 mg/day had a 2.3-fold increase in the odds of developing cysts. Src.
- Caffeine could cause incontinence. A study out of the University of Alabama showed that women who consume a lot of caffeine are 70% more likely to develop incontinence. Src.
- Caffeine may cause insomnia. Caffeine in a person’s system at bedtime can mimic the symptoms of insomnia. Src.
- Caffeine can cause indigestion. People who consume caffeinated beverages often report an upset stomach or indigestion. This mainly occurs when the beverages are consumed on an empty stomach. Src.
- Caffeine can cause headaches. While occasional doses of caffeine can relieve headache symptoms, the overuse of caffeine can cause headaches and lead to migraines. Src.
- Caffeine could reduce fertility in women. A study from The University of Nevada School of Medicine showed that caffeine can reduce a woman’s chances of becoming pregnant by about 27%. Src.
- Caffeine and miscarriage risk: In a recent study, both men and women who consumed at least two caffeinated beverages a day during the weeks prior to conception slightly increased the risks of a miscarriage. Src.
- Caffeine may not be healthy for type 2 diabetics. A study conducted by the American Diabetes Association showed that caffeine impaired glucose metabolism in those with type 2 diabetes. Src.
- Caffeine overdose. While overdose is rare, it can lead to many adverse symptoms including death, especially in those with underlying medical conditions. Some have a lower tolerance for caffeine than others. Src.
- Caffeine allergies. Some people have over-sensitivity to the caffeine molecule, which causes allergic-like reactions in the body such as hives and pain. Although not a true allergy, many report very negative symptoms after consuming even the smallest amounts. Src.
- Caffeine causes more forceful heart contractions. A recent study showed that immediately after energy drink consumption the heart produced more forceful contractions. It is unclear if this has any long-term health implications except for those with known health conditions. Src.
- Worse menopause symptoms. A recent study published in The Journal of The North American Menopause Society showed that menopausal women who consumed caffeine had a greater degree of vasomotor symptoms. Src.
- Caffeine consumption can lead to increased anxiety, depression and the need for anxiety medication. Src and Src. See also our article as to why caffeine causes anxiety and panic attacks.
- Caffeine increases the number of sugary beverages consumed by people, which contributes to obesity and diabetes. Src.
- Caffeine inhibits collagen production in the skin. This effect is dose-dependent but really heavy caffeine consumers should be aware. The study.
- Caffeine interferes with ossification and could also lead to a greater risk of bone fractures. This is dose-dependent, but heavy caffeine consumers should take note. Study 1 (pdf) Study 2.
- Caffeine does not help with prolonged sleep deprivation: This can lead to a false sense of security for those that have been sleep deprived for multiple days in a row and choose to get behind the wheel or do some other focus required task, thinking that as long as they have caffeine, they’ll be able to perform. Researchers from the American Academy of Sleep Medicine came to this conclusion after studying caffeine’s effects on their sleep-deprived test subjects. Here’s the study in detail.
- Caffeine may impair hearing loss recovery: For guinea pigs exposed to excessive levels of noise, caffeine was shown to delay the rate at which the guinea pigs recovered from noise-induced hearing loss. Here are the results of a recent study that investigated the problem. A correlation to humans is believed to exist but more research will be needed.
- Caffeine increases intraocular pressure when coupled with exercise: In this study, one group was given caffeine and the other a placebo. Both groups then engaged in low-intensity exercise. Those that consumed caffeine had higher intraocular pressure than those who did not consume caffeine. While for most people this isn’t a problem, those with eye disorders like glaucoma and other pressure-related eye disorders should be mindful of consuming caffeine and then working out. The full study is here.
When not managed caffeine can quickly become an out of control problem.
If you are experiencing any tell-tale signs of the risks above, then it’s time to start cutting back. Otherwise, it’s just a matter of time.
1. Download our book Awake (it's free).
2. Do the Overcoming Caffeine Withdrawal course at Udemy.
3. Use the Wean Caffeine supplement (something we helped get to market). It helps you avoid the painful withdrawal symptoms that often come when quitting caffeine abruptly.
Other Claims Against Caffeine
You may have heard or read about other negative health effects from caffeine consumption, but as of now, there just isn’t enough evidence to fully endorse those as legitimate health concerns.
Some of those negatives include:
- Adrenal fatigue
- Irregular heartbeat
- Accelerates bone loss. Src.
Caffeine is a drug and can affect people differently just like any other substance. It’s important that consumers understand how caffeine interacts with their bodies in regards to their personal health histories. For some consumers, swapping morning coffee for a shot of ginger or another naturally energizing beverage could be a better alternative. Sprint Kitchen has some good recommendations.
The food and beverage industry spends millions, if not billions, of dollars worldwide to fund studies and promote caffeinated products as safe or even healthy.
Fortunately, caffeine is one of the most researched substances on the planet and there does exist some unbiased data in which to glean some reliable information from.
While much of the research published does allude to the safety and even potential benefits of caffeine (in moderation), there are a handful of research studies that highlight the potentially harmful effects of caffeine.
The risks of suffering from any of the harmful effects of caffeine are diminished by being aware of how much is personally being consumed daily.
It is also important to be aware of any pre-existing medical conditions that may contribute to caffeine’s negative effects.