Heart palpitations are that sudden awareness of your heartbeat, whether it feels like it’s racing, fluttering, pounding, or skipping a beat. They account for roughly 16% of complaints in general practice, making them one of the most common reasons people visit a doctor. Most of the time, palpitations are harmless and triggered by something identifiable. But understanding the full range of causes helps you figure out what’s behind yours.
How a Normal Heartbeat Goes Off-Script
Your heart has a built-in electrical system that fires in a precise sequence, starting in the upper chambers and traveling down to the lower chambers. Palpitations happen when something disrupts that sequence, even briefly. The most common disruption is a premature beat, where a spot in the heart fires an electrical signal before it’s supposed to. This creates the sensation of a “skipped” beat, followed by a harder-than-usual thump as the heart resets.
Premature beats can originate in the upper chambers (premature atrial contractions) or the lower chambers (premature ventricular contractions, often called PVCs). Nearly everyone experiences these occasionally. They’re so common that finding a few on a heart monitor is considered normal. The feeling they produce, that brief flutter or pause, is usually what people mean when they say their heart “skipped a beat.”
Caffeine, Alcohol, and Other Stimulants
Caffeine is one of the most discussed triggers, and for good reason. It increases levels of stress hormones like adrenaline and affects how calcium moves inside heart muscle cells. Calcium flow is what drives each heartbeat’s contraction, so when caffeine amplifies it, the heart becomes more excitable. At moderate doses (two to three cups of coffee), most healthy people tolerate caffeine without issues. But at higher intake levels, or in people who are already sensitive, caffeine can increase the frequency of premature beats. One study found that patients who consumed caffeine before a cardiac procedure showed a marked increase in PVC frequency compared to those who didn’t.
Alcohol is another well-known trigger. Even a single episode of heavy drinking can provoke an irregular rhythm, sometimes called “holiday heart syndrome.” Nicotine stimulates the same stress hormone pathways as caffeine, raising heart rate and making the electrical system more irritable. Recreational stimulants like cocaine and methamphetamine carry a much more serious risk, capable of triggering dangerous heart rhythms even in young, otherwise healthy people.
Stress, Anxiety, and Panic
When you’re anxious or under stress, your sympathetic nervous system floods your body with adrenaline. This directly speeds up the heart’s natural pacemaker, producing a fast but regular heartbeat. During a panic attack, this surge can be intense enough that your heart rate spikes to 120 or 150 beats per minute within seconds. The relationship works both ways: an unexpected rhythm change can trigger a wave of anxiety, which then pumps out more adrenaline, which keeps the heart racing. Researchers have noted that the sympathetic arousal accompanying an arrhythmia is often experienced as panic rather than as a cardiac event, making it genuinely difficult to tell the two apart without a heart monitor.
Chronic stress and sleep deprivation can lower the threshold for premature beats over time. People who are already prone to PVCs often notice they worsen during periods of high emotional strain or poor sleep.
Hormonal Shifts
Your thyroid gland is one of the most powerful regulators of heart rate. An overactive thyroid (hyperthyroidism) increases the heart’s sensitivity to adrenaline, speeds up the natural pacemaker, and shortens the recovery time between beats. The result is a faster resting heart rate, a stronger heartbeat, and a higher likelihood of irregular rhythms. The intrinsic firing rate of the heart’s pacemaker is elevated in people with excess thyroid hormone, a direct effect on the heart rather than simply a byproduct of feeling “wired.” Hyperthyroidism also causes blood vessels to relax and widen, which drops blood pressure slightly and forces the heart to compensate by beating faster.
Pregnancy brings its own set of changes. Blood volume increases by nearly 50%, which means the heart has to work harder with every beat. Many pregnant women notice palpitations in the second or third trimester, and these are almost always benign. Menopause and perimenopause can also trigger palpitations as fluctuating hormone levels affect the cardiovascular system, though the exact mechanism is less well understood than the thyroid connection.
Medications That Can Trigger Palpitations
Several common medications list palpitations as a side effect. Decongestants found in cold and sinus medicines (the ones that clear your nose by constricting blood vessels) can speed up your heart. Asthma inhalers that open the airways also stimulate the heart through similar pathways. Blood pressure medications called vasodilators, which relax blood vessels, can cause a reflex increase in heart rate as the body tries to maintain blood pressure.
Stopping certain heart medications abruptly can also be a cause. Beta-blockers, which slow the heart, can produce a rebound effect if discontinued suddenly, leaving the heart temporarily more excitable than it was before you started taking them. If you’ve recently changed a medication and notice new palpitations, that timing is worth mentioning to your doctor.
Arrhythmias That Need Attention
While most palpitations come from benign premature beats or temporary triggers, some are caused by sustained arrhythmias that require treatment.
Atrial fibrillation (AFib) is the most common sustained arrhythmia. The upper chambers fire chaotically instead of in a coordinated rhythm, producing an irregular and often fast heartbeat. AFib can come and go on its own or persist until treated. It’s significant because it increases the risk of stroke, since blood can pool and clot in the quivering upper chambers.
Supraventricular tachycardia (SVT) causes a sudden, rapid heartbeat that starts and stops abruptly. People with SVT often describe it as a switch being flipped: one moment the heart is normal, the next it’s pounding at 150 to 250 beats per minute, and then it stops just as suddenly. SVT is rarely dangerous but can be frightening and disruptive.
Ventricular tachycardia (VT) originates in the lower chambers and produces a fast rhythm that can prevent the heart from filling properly. In people with otherwise healthy hearts, short bursts of VT may not cause serious problems. In people with existing heart disease, VT can be a medical emergency.
Other Common Triggers
Dehydration and electrolyte imbalances affect the heart’s electrical system directly. Potassium, magnesium, and calcium are essential for each heartbeat’s electrical cycle, and being low in any of them can increase premature beats. This is why palpitations sometimes show up after intense exercise, a stomach illness, or a period of not eating well.
Low blood sugar can trigger a burst of adrenaline as your body tries to mobilize energy, producing both palpitations and that shaky, anxious feeling. Fever and anemia both force the heart to beat faster to deliver oxygen, which some people perceive as palpitations even when the rhythm itself is normal.
How Palpitations Are Diagnosed
The challenge with palpitations is that they’re often gone by the time you’re sitting in a doctor’s office. A standard electrocardiogram (ECG) captures only a few seconds of your heart’s activity, so it may miss an occasional arrhythmia. That’s where wearable monitors come in.
A Holter monitor records your heart rhythm continuously for 24 to 48 hours. It’s useful when palpitations happen daily, but many people’s symptoms are less predictable. An event recorder, worn for up to seven days or longer, lets you press a button when you feel symptoms, capturing the rhythm at that exact moment. In a study of 310 patients, event recorders identified more symptomatic episodes than 24-hour Holter monitors, at lower cost per diagnosis. For people whose palpitations happen weekly or less often, event recorders are generally the better tool.
For very infrequent episodes, doctors can implant a tiny loop recorder under the skin that monitors continuously for up to three years. Blood tests for thyroid function, electrolytes, and blood count are standard parts of the workup, since they can reveal treatable causes that have nothing to do with the heart’s wiring.
When Palpitations Signal an Emergency
Most palpitations are brief, isolated, and harmless. But certain combinations of symptoms suggest the heart isn’t pumping effectively. Seek emergency care if palpitations occur alongside chest pain or pressure, fainting or near-fainting, severe shortness of breath, or severe dizziness. Palpitations that last several minutes at a very fast rate (above 150 beats per minute), occur during exertion, or happen in someone with known heart disease also warrant prompt evaluation. A single skipped beat while you’re sitting on the couch watching television is a very different situation from a racing heart that makes you lightheaded during a run.