Coffee is one of the most popular drinks in the world.
As a result, it is understandable that people don’t like to hear negative things about their favorite drink.
However, depending on the person, there can be both benefits and drawbacks to coffee.
Let’s be clear; most of the research on coffee is positive.
But it may not be a healthy choice for everyone.
This article takes a look at some of the potential negative side effects of coffee and who they might affect.
1. Coffee Contains Caffeine Which May Raise Blood Pressure
Studies show that coffee is generally healthy when consuming less than 400 mg of caffeine per day, but that negative effects can start to appear when we drink more than this (1).
However, the amount of caffeine in coffee can wildly vary.
For example, a Starbucks ‘Caffe Americano’ ranges from 75 mg to 300 mg of caffeine, depending on the size. If you’re brewing coffee at home, then the caffeine content will vary according to the type of coffee and brewing method (2).
Also, instant coffee typically contains the lowest amount of caffeine.
Since we all metabolize caffeine differently, individual tolerances will vary and it’s easy for some people to get “too much”.
Interestingly, it appears that coffee’s effect on acutely raising blood pressure disappears in regular coffee drinkers.
Studies hypothesize that this is due to frequent drinkers developing a tolerance to the blood pressure-raising effects of caffeine (5).
Can coffee cause hypertension?
If coffee can raise blood pressure, can it potentially lead to hypertension?
It seems the answer to this question is no; a systematic review of dose-response trials showed an inverse relationship between coffee consumption and hypertension (6).
2. Coffee May Cause Insomnia
Another disadvantage of drinking coffee is that it can potentially interfere with our sleep.
Some people can drink coffee right before bed and have a sound sleep, but it can leave others wide awake until the early hours.
Once again, the reason for this is that we all metabolize coffee (and caffeine) differently; some people do it quickly, others slowly.
Caffeine has a long half-life that averages around 5-6 hours for healthy individuals, but it can be even higher depending on liver health and several other factors (7).
Therefore, if you’re drinking coffee in the late afternoon or early evening, it may harm your sleep cycle. Studies support this too, with the highest caffeine intakes being associated with higher risk for insomnia (8).
However, a recent meta-analysis shows that low to moderate coffee consumption has an insignificant association with insomnia (9).
Additionally, when we drink coffee is important. Drinking coffee within 6 hours before bed appears to have disruptive effects on sleep quality (10).
3. Caffeine Withdrawal Leads To Negative Side Effects Such As Headaches
We should remember that caffeine is a drug, and like many drugs, there can actually be a withdrawal period when we give it up.
Some people try to quit coffee totally, and others (who are overdoing it) may try to cut down a little.
During this phase, many people experience painful headaches that subside if they consume caffeine again.
In a double-blind study, researchers examined the blood flow of participants during the initial days of caffeine abstinence.
This finding explains the commonly reported caffeine withdrawal side effects such as headaches, tiredness, and lethargy.
How long do these effects last?
Typically, these effects peak after one to two days of caffeine abstinence, and usually go away soon after (12).
4. Coffee May Worsen Acid Reflux and Heartburn Symptoms
Acid reflux and gastroesophageal reflux disease (GERD) can be extremely uncomfortable and frustrating for sufferers.
While there are various theories on what initially causes this condition, there are some foods/drinks that can trigger and worsen it.
Unfortunately, coffee is one of these, and people often report suffering from heartburn after drinking coffee.
There is no real conclusive evidence on exactly why this happens.
However, studies demonstrate that coffee can weaken the lower esophageal sphincter, a valve which keeps stomach acid out of the esophagus. For instance, in a trial of healthy participants, drinking coffee increased measurements of lower esophageal sphincter pressure (13).
Furthermore, a review of the literature found that coffee drinkers have significantly more GERD and erosive esophagitis than non-drinkers (14).
5. Caffeine Can Cause Anxiety and Panic Attacks
Caffeine may have an adverse impact on individuals predisposed to anxiety, panic attacks, and other such problems.
Several randomized studies show that coffee has anxiogenic (anxiety causing) properties and that consumption increases measures of anxiety (15).
The potential for caffeine to cause panic disorder and social anxiety have been under investigation for decades. One particularly convincing study was a randomized, double-blind experiment analyzing if coffee can make anxiety worse (16, 17).
This study featured 98 participants;
- 72 patients suffering from panic disorder or social anxiety.
- 26 control subjects
After taking a 480 mg dose of caffeine, 31 out of the 72 patients with anxiety problems suffered a panic attack. Out of the 26 control subjects, no-one had a panic attack.
One week later, participants had a second test and, unknowingly, they received a placebo (caffeine-free solution). No single participant had a panic attack from either group.
It’s therefore fairly clear that caffeine, and by definition, coffee, can induce panic attacks and stronger feelings of anxiety in those at risk.
However, in moderate amounts, there shouldn’t be any concern for individuals not prone to anxiety.
6. Coffee May Increase the Risk of Miscarriage in Pregnancy
Many expectant mothers avoid coffee due to fears over negative effects on their unborn baby.
However, research suggests that pregnant women don’t need to restrict coffee totally. That said, the potential for harm does seem to rise in a dose-dependent manner.
Over the past few years, four large-scale systematic reviews have looked into pregnancy risks associated with coffee and found;
- Results support an association between coffee/caffeine and spontaneous abortion. The advised limit of 2-3 cups of coffee (200 – 300 mg caffeine) could be too high (18).
- In a dose-response systematic review of 60 studies, greater caffeine intake correlated with a greater risk of spontaneous abortion and stillbirth (19).
- The risk of low birth weight increases in a linear manner alongside greater caffeine intake (20).
- Caffeine consumption at less than 200 mg per day “remains acceptable,” but higher amounts are associated with spontaneous abortion, and significantly so when people are consuming more than 500 mg of daily caffeine (21).
Overall, evidence suggests that a small amount of coffee (1 or 2 cups) is an “acceptable” risk.
However, as complications seem to rise in a dose-dependent manner, it may be better to avoid coffee entirely.
7. Coffee May Contribute to IBS and Other Digestive Problems
Irritable bowel syndrome (IBS) is a condition that is on the rise, and it has an estimated prevalence rate of 10-20% in Western countries (22).
Patients with IBS often suffer adverse side effects after consuming certain foods or drinks. Unfortunately, coffee is one of these, and it can often make IBS worse.
Sufferers often complain about IBS flare-up symptoms such as bloating and a burning feeling in the stomach after drinking coffee. This is particularly the case on an empty stomach.
This effect coffee has on IBS is possibly due to the way in which it acts as a stimulant on the colon.
The National Institute for Health and Care Excellence recommend that IBS patients limit coffee and tea consumption to 3 cups per day (25).
8. Some Coffee Drinks Contain Large Amounts of Sugar and Fat
While a daily cup of coffee may provide a range of health benefits, these will quickly disappear if that drink is a sugar-laden option.
Amazingly, some drinks at chain cafe stores contain upward of 60 grams (15 teaspoons) of sugar.
- Venti White Chocolate Mocha by Starbucks: 67 grams of sugar (approximately 17 teaspoons) (26).
- Large Vanilla Chai Latte from Dunkin Donuts: 66 grams of sugar (27).
While it’s always a good idea to limit sugar intake, these amounts are well over the upper limit set by the US dietary guidelines (28).
There’s no disguising that these are unhealthy drinks.
Additionally, homemade drinks such as bulletproof coffee can contain excessive amounts of fat and calories.
While there is nothing wrong with putting a little cream (or butter if preferred) in a coffee, drinking a meal’s worth of liquid fat isn’t the healthiest choice.
9. Some People Are Seriously Allergic/Intolerant To Coffee
Lastly, there are some people out there who are highly intolerant (or even allergic) to coffee.
Those who are genuinely allergic to coffee will have an adverse reaction and severe symptoms shortly after consuming it. Thankfully, such coffee allergies are incredibly rare, but they do occur and can even cause anaphylaxis (29).
With coffee intolerance, the effect it has on us mostly comes down to our genes.
Again, this is mainly down to the caffeine content since our genes determine if we are a “fast” or “slow” caffeine metabolizer.
Since some people cannot metabolize caffeine well, it has a much stronger impact on their body, especially when consuming large amounts in a short period. There is also a much higher risk of an accidental “overdose” in such people.
Some of these symptoms may include jitters, an increased heart rate, dizziness, and even extreme side effects such as shortness of breath or a tight feeling in the chest (30).
Anyone experiencing serious negative side effects from coffee should see their doctor. If it turns out that symptoms are solely related to the caffeine, then drinking decaf coffee is an easy switch to make.
Solving these potential problems with coffee is largely about following the sensible route.
No matter how much someone may love coffee, if it causes them to feel sick and suffer from side effects, then it just isn’t worth it.
On the other hand, some heavy coffee drinkers experiencing issues may benefit from reducing their intake, or possibly switching to decaffeinated drinks.
All in all, coffee is a healthy and enjoyable drink that contains several beneficial compounds.
Unfortunately, a small subset of the population may find it has negatives.