Having one too many cups of coffee can be like adding fuel to the fire.
If you’re anything like me (or the estimated 62% of Americans who drink coffee daily), you not only love the taste—you love the way your cup of joe makes you feel. From the increased focus to the mood boost, coffee’s simply the best.
But like all good things, there’s a flip side. Caffeine (the world’s most widely-used psychoactive drug) is a stimulant found in coffee, tea, soda, and chocolate. It can also be hiding in some medications and supplements, particularly weight control products. And, of course, in energy drinks, which can contain excessive amounts of caffeine.
According to the U.S. Food and Drug Administration, caffeine is generally safe in moderate amounts (under 400 milligrams daily) for healthy adults. Coffee, which is how the majority of us get our daily dose, typically contains 80 to 100 milligrams of caffeine per cup. A stronger brew will naturally contain more. Meanwhile, there’s anywhere from 40 to 250 milligrams of caffeine per 8 ounces in energy drinks.
Energy drinks also contain plant-based chemicals that have a stimulatory effect or build upon the available caffeine in the beverage, says James Giordano, Ph.D., a professor in the department of neurology and biochemistry at Georgetown University Medical Center, who warns against mixing coffee with other stimulants.
How does too much caffeine increase stress?
Just like family history, stress, financial concerns, world events, and interpersonal conflicts can impact stress, so can the things we put into our body, like caffeine, explains Natasha Bhuyan, M.D., West Coast Regional Medical Director at One Medical. In fact, caffeine can even trigger anxious events, like a panic attack, in certain people, she says.
Caffeine blocks the brain chemical that’s involved in helping you feel sleepy, called adenosine, explains Melissa Prest, D.C.N., M.S., R.D.N., C.S.R., L.D.N, foundation dietitian at the National Kidney Foundation of Illinois. When this is blocked, the central nervous system is ignited and releases the fight or flight hormones, like adrenaline and dopamine.
Additionally, caffeine is considered a stimulant that impacts the central nervous system. Every time you consume caffeine, your body increases your dopamine levels to help you feel alert and focused, Dr. Bhuyan explains. These are great side effects when we want to feel awake and alert.
“Imagine muscles that are being prepped for sudden exertion but there’s nowhere to go. This translates into what we know as the jitters,” she explains. The increased blood flow and heart contractions can even lead to palpitations, which can feel like a panic attack.
It’s like adding fuel to the fire, according to Lina Begdache, Ph.D., a nutrition scientist and assistant professor of health and wellness studies at Binghamton University. “In small amounts caffeine can actually boost your mood,” she says. But if you exceed certain levels, it will increase (and prolong) the stress response past the point of being helpful.
Can caffeine make anxiety worse?
According to Wolkin, research indicates that caffeine can aggravate and maintain an anxiety disorder. The impact of coffee can be so pervasive and play such a clear role in exacerbating someone’s anxiety that she asks all new patients about their caffeine consumption.
If she later notices that coffee is intensifying, or helping to maintain, some of the anxiety a person is experiencing, she recommends weaning off slowly in conjunction with their therapeutic work.
But what are the symptoms of anxiety? “Anxiety is a feeling of intense, persistent, and/or difficult-to-manage worry, dread, or fear regarding everyday circumstances and situations,” says Amie DiTomasso, L.G.S.W., a therapist at The Dorm. Anxiety not only impacts your mental state, but it has physical symptoms too, including dizziness, nausea, shortness of breath, muscle tension, and difficulty breathing, she explains.
But the symptoms of anxiety and too much caffeine can overlap, Prest warns. You may feel a rapid heartbeat, gastrointestinal distress, restlessness, and other symptoms that feel very similar, so it can be difficult to distinguish the two if you’re already someone who experiences anxiety, she says.
Dr. Bhuyan notes that everyday anxiety can evolve into a generalized anxiety disorder, and she encourages people to discuss their mental health status with their primary care provider. Prest adds that there is a diagnosis of caffeine-induced anxiety disorder that is classified by caffeine impacting everyday functioning. In any case that you’re concerned about your anxiety, it’s important to seek help from your health provider.
Additionally, caffeine use can also become a vicious cycle for those with underlying anxiety, according to Jenicka Engler, Psy.D., a psychologist and clinical scientist in Massachusetts. For example, someone with anxiety may be dealing with fatigue due to trouble sleeping, so they’ll turn to coffee to perk up throughout the day. But, in turn, glugging down too much caffeine makes them feel even more anxious and prevents them from falling (and staying) asleep at night. And then the cycle repeats.
How many cups of coffee are too many?
It depends. Caffeine affects all of us differently for various reasons, including bodyweight, gender, tolerance, and so on. But in general, around two cups of coffee (200 milligrams of caffeine) won’t cause a great deal of symptoms for the average person, according to Rashmi Goyal, M.D., an internal medicine specialist at The University of Toledo Medical Center.
“Over 400 milligrams of caffeine (about 4 cups of coffee) may bring out symptoms of anxiety,” Dr. Goyal says. Drinking more than 1,200 milligrams can even cause seizures in some individuals.
“Imagine muscles that are being prepped for sudden exertion but there’s nowhere to go.”
However, that all depends on personal sensitivities and rates of metabolism. People who metabolize caffeine at slower rates end up compiling more caffeine in their system, and are thus impacted by fewer cups of coffee. Rapid metabolizers absorb, break down, and eliminate caffeine more quickly, so they can generally drink more cups before feeling anxious.
There are certain people who have a genetic defect in the liver enzyme that metabolizes caffeine, explains Begdache, which makes them slow metabolizers. Caffeine also affects young people, who have more sex hormones competing with caffeine for metabolism, and women in general, who have higher levels of estrogen and are more susceptible to mood disorders.
Some people may also be more sensitive to caffeine, says Dr. Giordano, perhaps due to certain medications or an underlying condition that makes them more predisposed to caffeine’s stimulating effects.
How to find your caffeine threshold
Since there’s not a one-size-fits-all dose of caffeine for everyone, it’s important to determine your own threshold. The main way to do that is to pay attention to how you feel as you drink coffee or other caffeinated drinks throughout the day.
If you’re trying to decide if you’re having too much caffeine, Prest suggests focusing on those not-so-fun side effects like insomnia, nervousness, irritability, rapid heart rate, and anxiety, and seeing if they’re regular experiences for you and impacting your daily life. “If you’re having these symptoms, feeling a bit wired, maybe that’s someone who should cut back,” she says.
Start by spending a few days taking extra notice of your anxiety symptoms and when and how much caffeine you consumed, suggests Sheli Msall, R.D.N., L.D., a registered dietitian at The Dorm. “Look for any correlations of possible anxiety symptoms to caffeine intake, taking into account other events of the day that might have impacted stress and anxiety levels as well,” she says.
And if you’re finding these symptoms only happen sometimes, like when you have a cup of coffee later in the evening, consider adjusting your caffeine consumption schedule. Prest says it can take four to six hours to metabolize half of what you’ve consumed, so late-day caffeine can sometimes impact your sleep pattern and side effects.
“It definitely takes some level of interoceptive awareness, which is awareness of our own inner body sensations,” explains Wolkin. When you start to feel tense, jittery, and like everything’s sped up—that’s a clue you’ve reached your limit. Take note of how much caffeine you’ve had once those feelings surface and aim to cap your intake before you hit that amount.
But experts warn against quitting cold turkey. The symptoms of caffeine withdrawal are very real and unpleasant, leading to headaches, fatigue, difficulty concentrating, irritability, and even muscle pain.
Giordano recommends gradually tapering off the amount of caffeine you drink in a day, allowing your system to return to normal in a more metered way. If you’re a coffee drinker, the Cleveland Clinic recommends alternating between regular and decaf at first, particularly if the taste of coffee is what you’re really after. (Coffee has a very strong conditioning effect that can act as a placebo due to its smell and taste, says Giordano.)
Prest suggests mixing half caffeinated with decaf or trying a caffeine-free product in place of some of your caffeinated drinks, like ginseng tea or maca root power that offer energy without the caffeine.
Try this for at least two to three weeks—gradually bringing down the amount of caffeine you drink in a day—and see what it does for you. This way, you can wean off slowly and return to an amount that feels healthy for you.