If you’re like most Americans, your day hasn’t started until you’ve had your first cup of coffee. In fact, according to the National Coffee Association’s National Coffee Drinking Trends annual report, 64 percent of Americans have a coffee habit, and drink the stuff on a daily basis. And their ranks continue to grow—that number is a seven percent jump from just two years earlier.
However, as coffee consumption continues to increase throughout the United States, so does the number of individuals who are feeling the effects of overdoing it. While the risk of an actual caffeine overdose is so low as to be statistically insignificant—just 51 have been reported over a 58-year period—there are frequent side effects that stem from overconsumption that even those attuned to their bodies can easily miss.
“The effects of caffeine are individualized, so it’s best to assess on a case-by-case basis where exactly the tipping point is where caffeine may provide beneficial effects and where it creates diminishing returns,” says Ariane Hundt, MS, a New York-based clinical nutrition coach and fitness expert, who suggests that those who are experiencing more than just alertness from their usual cup of joe might be overdoing it. With that in mind, we’ve rounded up 20 subtle signs you’re drinking too much coffee, from the mildly concerning to the seriously dangerous.
1. You bruise easily.
If you’re feeling weak, suddenly bruising easily, or find yourself more lethargic than normal, your coffee habit could be to blame. “Coffee inhibits the absorption of iron,” says Hundt. Over time, this can lead to iron deficiency, or even anemia, if left untreated.
2. Your heart constantly races.
When your heart races, say, in the presence of your crush, that’s not a bad thing, but when it’s a daily feeling, it could be the result of your coffee habit. Caffeine has been known to trigger heart palpitations, meaning that a second cup of cold brew could be the reason behind a sudden flutter in your chest.
3. Your belly’s getting bigger.
While minor caffeine consumption has been linked to weight loss, overdoing it could put you at risk for a widening waistline. In fact, according to research published in the Journal of Agricultural and Food Chemistry, drinking five or more cups of coffee a day can actually increase your risk of developing excess belly fat.
4. Your blood pressure is soaring.
That increased heart rate after a few cups of coffee isn’t the only change your Starbucks fix could be having on your cardiovascular health. Researchers at Wageningen University in The Netherlands have linked coffee consumption of over five cups a day to increases in blood pressure, potentially putting you at risk for hypertension and stroke.
5. You’re anxious.
Those rapid thoughts and your nervous energy could be more than just run-of-the-mill stress. “This has to do with caffeine increasing your heart rate by triggering the hormones cortisol and adrenaline, thus resulting in a short-term stress response,” says Hundt.
6. You have shaky hands.
If you’ve noticed a sudden tremor in your hands, it might be time to revisit your coffee intake. Multiple studies have linked the consumption of caffeine to increased shakiness, so when you find yourself trembling for no particular reason, consider skipping the second (or third, or fourth) cup of coffee.
7. You’re always tired.
While coffee may initially give you a boost of energy, if you’re overdoing it, don’t be surprised when you feel wiped out afterward. Coffee interferes with the absorption of vitamin B1, otherwise known as thiamine, which can lead to fatigue. Worse yet, this symptom is often compounded by the insomnia coffee tends to provoke, leaving you in a seemingly never-ending cycle of sleepless nights.
8. Your insulin receptors are off-kilter.
A few extra cups of coffee a day could put your body in some serious trouble. “[Coffee] gets you going by increasing your blood sugar by releasing glucose,” explains Hundt. Over time, this can impair your body’s insulin receptors, meaning you no longer respond properly to the effects of insulin and may develop insulin resistance, potentially increasing your risk of type 2 diabetes in the long run.
9. You’re parched.
“Too much caffeine is dehydrating and makes you lose water through frequent urination,” says Hundt. “How much caffeine it takes to create that depends on a few other factors, such as your adrenaline levels and stress, but you can be sure that consuming more than three cups of coffee a day is going overboard.” Over time, the diuretic effects of drinking too much coffee can lead to serious dehydration, which can cause everything from cognitive confusion to heart rhythm issues.
10. Your blood sugar levels are out of whack.
According to doctors at the Mayo Clinic, those who already have diabetes might want to keep their coffee consumption to a minimum. While some research suggests that drinking coffee may reduce your risk of developing diabetes, coffee has also been known to affect blood sugar levels, posing a potential risk to those already struggling with the condition.
11. You’re irritable.
That sudden urge to snap at your co-workers or your significant other? Blame it on those espresso shots you had this afternoon. Along with an increased predisposition to anxiety, too much coffee can make you irritable and prone to being short-tempered.
12. You’re nauseous.
That queasy feeling in your stomach just might stem from the extra cup of dark roast you snagged at Starbucks. The combination of increased blood pressure, dehydration, and caffeine’s high acidity level can wreak havoc on your stomach, making you feel queasy all day. “In higher doses, [coffee consumption] can progress to nausea,” says Dr. Christopher Hollingsworth, MD, of NYC Surgical Associates.
13. You have muscle cramps.
Your aching muscles might be more closely related to your drink of choice than your workout routine. Drinking too much coffee can impair your digestive tract’s ability to absorb magnesium, potentially leading to a deficiency. And one of the side effects of a magnesium deficiency? You guessed it: muscle cramps.
14. You have serious eye pressure.
That intraocular pressure you’re experiencing could have started with that extra cup of coffee you downed this morning. Caffeine can increase your blood pressure, thus increasing pressure in the eyes and putting you at risk for glaucoma over time. Worse yet, if left untreated, this can even lead to irrevocable vision damage or even blindness.
15. Your bones break easily.
Nearly 54 million Americans have low bone density or osteoporosis, meaning they’re more susceptible to potentially-debilitating falls and broken bones. Unfortunately, those extra cups of coffee could be putting you at risk: in fact, researchers at Creighton University have discovered that caffeine intake is significantly correlated with bone loss in older women.
16. Your teeth are discolored.
If you’re feeling less than pleased with your smile, you might want to start thinking about limiting your coffee consumption. The acids in coffee can contribute to decreased mineralization in teeth, leading to enamel erosion over time. Coupled with coffee’s staining effect, you’ve got a recipe for some not-so-pearly whites.
17. You can’t sleep.
Anyone who’s ever found themselves tossing and turning after having a cup of coffee too close to bedtime won’t be surprised to discover that insomnia and over-consumption of coffee go hand-in-hand. “If you’re having trouble falling asleep, try laying off coffee by 1:00 p.m. to ensure the caffeine has been metabolized by bedtime. Also, skip the night time cup of green tea and piece of chocolate as these too contain caffeine, while smaller doses, but can still affect sleep,” suggests Hundt.
18. Your stomach hurts.
Those stomach pains you have after too many cups of coffee shouldn’t be ignored. On its own, coffee’s high acid content can cause stomach pain and may increase the risk of stomach lining erosion and ulcers. Unfortunately, continued over-consumption can exacerbate these issues, even leading to bleeding in the digestive tract over time.
19. You’re losing weight.
While losing a few pounds may be on your to-do list, but if you’re losing weight unintentionally, you may want to consider cutting back on the coffee. In addition to making your stomach more sensitive, overconsumption of coffee can trigger a thiamine deficiency, a symptom of which just so happens to be nausea. Combined with coffee’s diuretic effect, you may shed a few pounds, but the process by which you’re doing so is anything but healthy.
20. You’re feeling weak.
All those trips to the bathroom that accompany your cups of coffee could be leading to some serious electrolyte imbalances over time. In addition to its magnesium-absorption-inhibiting effects, coffee’s diuretic effects can throw your electrolytes out of whack, potentially leading to weakness and fainting, as well as heart palpitations, nausea, fatigue, and vomiting.
21. You have difficulty breathing.
If you’re panting but haven’t hit the gym in days, it’s time to reconsider your coffee intake. Coffee over-consumption can lead to both magnesium difficulties and an irregular heartbeat, the combination of which can set you up for breathing problems before you know it.
22. Your skin is dull.
Before you shell out hundreds for a pricey moisturizer, try stepping away from the coffee pot first. Coffee’s diuretic effects can cause dehydration, a condition that can make your skin dull and lifeless.
23. You’re sweating excessively.
Those extra sweaty days aren’t always a sign of a well-done workout. In fact, it could be the result of those extra shots in your Americano at breakfast. Caffeine can interfere with your body’s magnesium absorption, and when left untreated, a magnesium difficulty can leave you sweating bullets.
24. You have frequent headaches.
That intense pressure in your head? Blame it on your cold brew addiction. The combined effects of dehydration and increased blood pressure caused by too much coffee can do a number on your head, so before popping another pain reliever, which can hurt your liver or even cause you to have a heart attack, think about skipping that extra cup of Joe first.
25. Your mouth is dry.
If your mouth is as dry as the Sahara (and you’ve got the less-than-charming breath to go along with it), it’s time to step away from the Keurig. The dehydrating effects of caffeine over-consumption can lead to persistent dry mouth, and when combined with coffee’s enamel-eroding effects, can lead to serious tooth decay over time.