Heart palpitations feel like your heart is pounding, fluttering, or skipping a beat. They’re one of the most common reasons people visit a cardiologist, and most of the time they’re harmless. But the list of things that can set them off is surprisingly long, ranging from your morning coffee to a thyroid problem you didn’t know you had.
Caffeine, Alcohol, and Nicotine
Stimulants are among the most common palpitation triggers. Caffeine blocks receptors in the brain that normally have a calming, sedative effect, while also boosting dopamine activity. The result is a more alert, more stimulated nervous system, and for some people that translates directly into a racing or fluttering heart. The threshold varies widely from person to person. One cup of coffee may be fine; three may not.
Nicotine is a potent activator of the sympathetic nervous system, the branch responsible for your fight-or-flight response. Every cigarette, vape hit, or nicotine pouch gives that system a push, which can raise your heart rate and trigger irregular beats.
Alcohol is more complex. In small amounts it stimulates several brain signaling systems, but at higher doses it acts as a depressant. Either way, it can irritate the heart’s electrical system. Binge drinking is especially risky. Sometimes called “holiday heart,” a bout of heavy drinking can trigger episodes of atrial fibrillation even in people with no underlying heart disease.
Stress, Anxiety, and the Fight-or-Flight Response
When you feel anxious or threatened, your autonomic nervous system fires up. Adrenaline floods your bloodstream, your heart rate climbs, and your heart may start beating harder or less regularly. These palpitations can feel identical to a heart problem, which often makes the anxiety worse and creates a feedback loop.
Palpitations from anxiety sometimes come as single early or delayed heartbeats that break the normal rhythm. You might feel a “skip” followed by a hard thump as the heart resets. This is usually a premature beat, not a dangerous arrhythmia, but it can be alarming if you don’t know what’s happening. Chronic stress, sleep deprivation, and panic attacks are all common triggers.
Hormonal Changes in Women
Palpitations are strikingly common during hormonal transitions. Up to 42% of perimenopausal women and 54% of postmenopausal women report them. The exact mechanism linking fluctuating estrogen levels to heart rhythm changes isn’t fully understood, but the pattern is consistent and well documented. These palpitations often arrive alongside hot flashes, sleep disruption, and mood changes, and the whole cluster of symptoms can persist for a decade or longer during the transition from perimenopause to postmenopause.
Pregnancy is another hormonal window where palpitations are common. Blood volume increases dramatically, the heart works harder to supply the placenta, and hormonal shifts alter how the cardiovascular system responds. Most pregnancy-related palpitations are benign, but they’re worth mentioning to your provider, especially if they come with dizziness or shortness of breath.
Thyroid Problems
An overactive thyroid (hyperthyroidism) is one of the most important medical causes to rule out. Excess thyroid hormone decreases resistance in your blood vessels while simultaneously increasing heart rate, the force of each contraction, and overall blood volume. The combined effect can push cardiac output 50% to 300% higher than normal.
Sinus tachycardia, a sustained fast heart rate, appears in nearly all patients with hyperthyroidism. Atrial fibrillation, a more chaotic rhythm, develops in 2% to 20% of cases. Thyroid hormone directly alters the electrical properties of heart cells and can enlarge the upper chambers of the heart, both of which make irregular rhythms more likely. A simple blood test can check your thyroid levels, and treating the underlying thyroid condition typically resolves the palpitations.
Anemia and Low Iron
When your blood doesn’t carry enough oxygen, either from low iron, blood loss, or another cause of anemia, your heart compensates by beating faster and harder. That increased workload is often what people feel as palpitations. Anemia-related palpitations tend to get worse with exertion and improve with rest. They’re commonly accompanied by fatigue, lightheadedness, and pale skin. Correcting the anemia, whether through dietary changes, supplements, or treating the underlying cause, usually brings the heart rate back to normal.
Over-the-Counter Medications
Decongestants are a surprisingly common and often overlooked trigger. Medications containing pseudoephedrine or similar ingredients (typically marked with a “D” after the brand name) work by constricting blood vessels in the nasal passages to dry up mucus. But that same vessel-constricting effect happens throughout the body, raising blood pressure, increasing heart rate, and sometimes causing skipped beats. If you already have a heart condition, palpitations from a decongestant can last several hours.
Asthma inhalers that contain bronchodilators can have a similar stimulating effect. Diet pills, energy supplements, and anything with high doses of caffeine or synephrine also belong on the list. If your palpitations started around the same time you began a new medication or supplement, that timing is worth paying attention to.
POTS and Positional Triggers
Postural orthostatic tachycardia syndrome (POTS) causes a dramatic heart rate spike when you stand up. The diagnostic threshold for adults is a heart rate increase of more than 30 beats per minute, or a rate that exceeds 120 beats per minute, within 10 minutes of standing. For adolescents, the threshold is an increase of at least 40 beats per minute.
POTS became more widely recognized after COVID-19, as many people developed the condition following infection. But it can also follow other viral illnesses, surgery, or trauma. Beyond palpitations, POTS typically causes lightheadedness, brain fog, and fatigue that worsen with standing and improve when lying down. If your palpitations are clearly tied to changes in position, POTS is worth investigating.
Other Common Triggers
Dehydration reduces blood volume, forcing the heart to beat faster to maintain circulation. Eating a large, carbohydrate-heavy meal can temporarily shift blood flow to the digestive system and trigger palpitations, especially if the meal is followed by a sugar crash. Electrolyte imbalances, particularly low potassium or magnesium, affect the heart’s electrical signaling and can cause both premature beats and sustained arrhythmias. Fever from any cause raises the heart rate roughly 10 beats per minute for each degree above normal.
How Palpitations Are Diagnosed
The challenge with palpitations is that they’re often intermittent. A standard electrocardiogram (ECG) only captures your heart’s rhythm for about 10 seconds, so it may look completely normal if your palpitations aren’t happening at that exact moment.
A Holter monitor solves this by recording your heart’s rhythm continuously for one to two days. You wear a small device with electrodes on your chest and go about your daily routine. If your palpitations happen less frequently than every couple of days, an event monitor is a better option. These devices record over several weeks and are activated either automatically when they detect an abnormal rhythm or manually when you press a button during symptoms. Blood tests for thyroid function, hemoglobin, and electrolytes round out the basic workup.
When Palpitations Are a Warning Sign
Most palpitations are not dangerous, but certain accompanying symptoms raise the stakes. Seek immediate care if your palpitations come with:
- Fainting or near-fainting, especially if you injure yourself during an episode
- Chest pain or shortness of breath
- A resting heart rate above 120 or below 45 beats per minute
- A new irregular rhythm that feels different from occasional skipped beats
A family history of sudden cardiac death also changes the picture significantly. In that case, even isolated palpitations deserve a thorough cardiac evaluation rather than watchful waiting.