What causes heart palpitations?

The common causes are caffeine, alcohol, nicotine, stress and anxiety, strenuous exercise, lack of sleep, some medicines, and pregnancy or menopause. Medical causes include extra beats, rhythm problems such as AFib, an overactive thyroid, anemia, low potassium, low blood sugar and heart valve disease.

Are heart palpitations dangerous?

Usually not. The NHS says they are common and "not usually a sign of anything serious." But in one series of people evaluated for palpitations, 43% had a heart cause, so new or frequent palpitations deserve an ECG. Palpitations with chest pain, fainting or severe shortness of breath need 911.

How do you stop heart palpitations?

For palpitations with no medical cause, the NHS suggests avoiding the triggers: stress, smoking, caffeine and alcohol. If an episode will not stop, or comes with chest pain, fainting or shortness of breath, call 911. Specific treatment depends on the cause found on an ECG or monitor.

Can anxiety cause heart palpitations?

Yes. Stress and anxiety are among the commonest triggers, and in one series of people evaluated for palpitations, psychiatric causes such as panic disorder explained 31%. Anxiety and a rhythm problem can also happen together, so anxiety is a conclusion reached after the ECG, not before.

Does coffee cause palpitations?

It can for some people, and the NHS lists caffeine as a trigger. In a 2023 trial, days with caffeinated coffee brought no significant rise in extra beats from the upper chambers but about 50% more extra beats from the lower chambers, and less sleep. A larger 2016 study found no link between regular caffeine intake and extra beats on a 24-hour recording.

What blood tests check for the cause of palpitations?

A 2017 American Family Physician review lists a complete blood count, kidney tests (BUN and creatinine), electrolytes such as potassium, and thyroid function tests, alongside a 12-lead ECG. A fasting glucose is added when low blood sugar is a concern.

Heart palpitations: what they feel like, what causes them

Q: What do heart palpitations feel like?

The NHS describes a heartbeat that is racing or very fast, irregular with skipped or extra beats, pounding or thumping, or fluttering, felt in the chest, neck or throat. Many people describe a single thump followed by a pause, which is often an extra beat.

Q: Why do I get heart palpitations at night?

Cleveland Clinic notes that night-time palpitations are the same as daytime ones, but you may notice them more at night because you are not busy or distracted. An evening drink or a late coffee can add to it. Palpitations that disrupt sleep were linked with a higher chance of a heart cause in the research behind a 2017 primary care review, so they are worth raising.

Quick answer

Heart palpitations are a sudden awareness of your heartbeat: racing, pounding, fluttering or skipping. ¹ They are common and usually not serious, and the everyday causes are caffeine, alcohol, nicotine, stress and anxiety, hard exercise, poor sleep, some medicines, and pregnancy or menopause. ¹³ Medical causes include harmless extra beats, rhythm problems such as atrial fibrillation (AFib), an overactive thyroid, anemia and low potassium. ¹²³ In one series of 190 people evaluated for palpitations, the cause was in the heart in 43%, which is why every person checked gets an electrocardiogram (ECG, a recording of the heart's electrical signal), with TSH, a blood count and electrolytes as the usual blood tests. ⁴⁵⁶ Palpitations with chest pain, fainting or near-fainting, or severe shortness of breath need 911. ¹²

The distinctions

01
Feeling your heartbeat is not the same as a rhythm problem
A pounding heart after coffee or during a panic attack is a normal rhythm you have noticed. A rhythm problem such as atrial fibrillation is the heart's electrical timing going wrong. They can feel alike, and only an ECG or a heart monitor recording taken during the feeling tells which one it is.
02
Blood tests check what drives palpitations, not the rhythm itself
TSH, a blood count and potassium look for an overactive thyroid, anemia and low potassium, which can push the heart to beat fast or irregularly. A normal blood panel does not rule out a rhythm problem; the ECG and, if needed, a monitor worn for days or weeks do that.

Heart palpitations are a sudden awareness of your own heartbeat: racing, pounding, fluttering, or a beat that seems to skip. ¹ Most come from something everyday, such as caffeine, alcohol, nicotine, stress, a hard workout, a short night, a cold medicine or pregnancy. ¹²³ Some are a heart rhythm problem, such as atrial fibrillation (AFib, an irregular rhythm from the heart's upper chambers), and some come from an overactive thyroid, anemia (too few red blood cells) or low potassium. ¹³ The test that tells the difference is an electrocardiogram (ECG), a short recording of the heart's electrical signal, ideally taken while the palpitations are happening. ⁵⁶

When to get help now

Most palpitations pass on their own. These signs mean the heart may not be pumping well, and that needs help now. If the signs have already stopped, the NHS still advises an urgent same-day appointment. ¹ Do not drive yourself to the emergency room.

Call 911 or your local emergency number

Palpitations with chest or arm pain or pressure ²³
Fainting or passing out, or feeling about to faint ¹²
Severe shortness of breath or trouble breathing ¹³
A racing or pounding heart that will not stop ¹³
Palpitations with heavy, unusual sweating or dizziness ²

See a doctor soon, the same day if you can

Palpitations that are new, or feel different from before ²
Extra beats more than 6 a minute, or coming in groups of 3 or more ²
A resting pulse over 100 when you are not exercising, anxious or feverish ²
Palpitations that come on during exercise ⁵
Palpitations that keep coming back, are more frequent, or last more than a few minutes ¹
A heart condition, or a family history of heart problems or sudden death at a young age ¹⁵

LifeFrom can't examine you or assess a symptom. If something feels seriously wrong, trust that and get care rather than waiting on a test.

What are heart palpitations, and what counts as normal?

Most of the time you feel none of your heartbeats. A palpitation is any moment you do notice it, and it is unpleasant or unusual. The NHS lists four common descriptions: racing or beating very fast, irregular with skipped or extra beats, pounding or thumping, and fluttering, felt in the chest, neck or throat. ¹ MedlinePlus adds that the rhythm underneath can be normal or abnormal. ²

Some awareness is normal. A heart that pounds after stairs, a fright or a strong coffee is doing its job. MedlinePlus advises contacting a provider right away for a resting pulse over 100 without exercise, anxiety or fever, or for extra beats "more than 6 per minute or coming in groups of 3 or more." ² An occasional skipped beat, felt as a thump and a pause, is very common and is usually an extra beat (an ectopic beat). ¹

Noticing a normal beat, or a rhythm problem: only a recording tells

A normal rhythm you have noticedCommon, often from caffeine, stress, exercise or a short night

Sinus rhythm, the heart's usual pacemaker

How it often feelsFast and regular, or a single thump and pause

How it often startsBuilds with a trigger and eases with rest

What the ECG showsA normal rhythm, sometimes with extra beats

Next stepLook at triggers; see a clinician if it keeps coming back

A rhythm problemNeeds a recording during the symptom to find

For example AFib or another arrhythmia

How it often feelsFluttering, irregular, or very fast; sometimes nothing at all

How it often startsCan come on at rest or wake you

What the ECG showsThe abnormal rhythm, if recorded while it happens

Next stepECG, then a monitor worn for days or weeks if needed

Feelings overlap, which is why clinicians rely on the recording. Some people with AFib feel nothing and don't know they have it. Sources: MedlinePlus, American Family Physician 2024. ⁶⁷

43%of 190 people evaluated for palpitations had a heart cause31% had a psychiatric cause such as panic disorder, 10% another cause, and 16% no cause found. Source: American Family Physician, 2011. ⁴

What can cause it, most likely first

Ranked from most to least likely in adults in general, as triggers people notice. The order shifts with age, sex and history: rhythm problems such as AFib become more common after 65, and a heart condition, a new medicine or pregnancy moves that cause up the list. ⁷

01
Caffeine, alcohol, nicotine and stimulantsEverydaycommon
Caffeine, alcohol and nicotine are on every major list of triggers, and so are recreational stimulants such as cocaine and amphetamines. ¹²³ Energy drinks and pre-workout powders carry caffeine too. Caffeine affects people differently: in a 2023 trial, coffee days brought more extra beats from the heart's lower chambers but not from the upper chambers. ⁸ Heavy drinking also raises the risk of AFib. ⁷
02
Hard exercise, poor sleep, dehydration and feverEverydaycommon
Strenuous exercise and lack of sleep are on the NHS list, and Cleveland Clinic adds dehydration. ¹³ Fever speeds the heart up too. ² A pounding heart during a workout that settles with rest is expected; palpitations that come on during exercise with dizziness or chest pain are not, and need 911. ²⁵
03
Stress, anxiety and panic attacksMedicalcommon
Stress, anxiety, panic and fear are among the commonest triggers. ¹² In one series, psychiatric causes such as panic disorder explained 31% of palpitations that were evaluated. ⁴ No blood test checks for anxiety. A 2024 review advises looking for it once an ECG has not found a rhythm problem, because the two can sit together. ⁶
04
Medicines and decongestantsEverydaycommon
Decongestants such as phenylephrine and pseudoephedrine, diet pills, asthma inhalers, thyroid hormone and some heart and blood pressure medicines can cause palpitations. ²³ A start date that lines up with the palpitations is a strong clue. Do not stop a prescribed medicine on your own; the prescriber can weigh the options.
05
Pregnancy and menopauseEverydaycommon
The NHS says pregnancy and menopause can sometimes cause palpitations, and Cleveland Clinic lists pregnancy among the causes. ¹³ For women in their 40s and 50s, palpitations can arrive alongside hot flashes and night sweats. Palpitations in pregnancy with breathlessness, chest pain or fainting still need urgent care, the same as at any other time. ¹
06
Extra beats (ectopic beats)Medicalcommon
An extra beat comes a little early, and the pause after it makes the next beat feel like a thump; that is the skipped beat many people feel. ¹ Extra beats are common and usually harmless in a healthy heart. Very frequent ones, more than 6 a minute or in groups of 3 or more, are a reason to contact a provider. ²
Electrocardiogram (ECG)
A normal ECG with occasional extra beats is common; frequent extra beats, or runs of them, are a reason for a longer monitor. ²⁵
07
Heart rhythm problems such as AFibMedicalless common
Atrial fibrillation is one of the most common rhythm problems; it can feel like fluttering, pounding or a heart beating too fast, and some people feel nothing. ⁷ It can raise the risk of stroke, and the risk climbs after 65, with heavy drinking, an overactive thyroid and sleep apnea. ⁷ In a 2017 review, AFib explained 16% of palpitations evaluated and supraventricular tachycardia (SVT, a fast regular rhythm from above the lower chambers) 10%. ⁵ Heart valve disease and structural heart problems are less common causes. ¹⁵
Electrocardiogram (ECG)
An abnormal rhythm on the ECG points to an arrhythmia; a normal ECG between episodes does not rule one out, which is why a monitor worn for days or weeks may follow. ⁵⁶
Heart rhythm
An irregular rhythm flagged by a smartwatch or phone ECG can point toward AFib, but these devices have high false-positive rates, so a clinician confirms it on a medical ECG. ⁶
08
Overactive thyroidMedicalless common
An overactive thyroid (hyperthyroidism) speeds the body up, with a rapid or irregular heartbeat among its symptoms, along with weight loss, heat intolerance and nervousness. ¹¹ Left untreated, it can cause an irregular heartbeat that leads to blood clots, stroke or heart failure. ¹¹ Thyroid tests are part of the standard first round for palpitations. ⁵
Can be linked with Hyperthyroidism
TSH
A low TSH (thyroid stimulating hormone) points to an overactive thyroid, because the pituitary makes little or no TSH when thyroid hormone is high. ¹³ High-dose biotin can make TSH look falsely low. ¹⁴
Free T4
A high free T4 (the main thyroid hormone) alongside a low TSH fits an overactive thyroid. ¹³ See how to read your thyroid panel.
09
Anemia and low ironMedicalless common
Anemia means too few red blood cells or too little hemoglobin to carry oxygen, and the NHS and Cleveland Clinic both list it as a cause of palpitations, with iron deficiency named by the NHS. ¹³ Tiredness, breathlessness on stairs and pale skin often come with it; see fatigue for more. A clinician decides on iron after a test, because low iron needs a reason found.
Can be linked with Anemia
Hemoglobin
A low hemoglobin on the complete blood count points to anemia, one of the drivers a 2017 review lists the blood count to exclude. ⁵ See the CBC explainer.
Ferritin
A low ferritin points to low iron stores, the cause behind iron deficiency anemia, which the NHS lists as a cause of palpitations; the reason for the low iron is then looked for. ¹
10
Low potassium, magnesium or blood sugarMedicalless common
Low potassium can cause a feeling of skipped beats or palpitations, and a large drop can cause abnormal rhythms; water pills (diuretics), vomiting, diarrhea and low magnesium are common reasons. ¹⁰ Low blood sugar can cause a fast or irregular heartbeat, shakiness and dizziness, mostly in people on insulin or some diabetes pills. ¹² Both are checked with a blood test, and both are corrected by a clinician who knows the level, kidney function and medicines.
Potassium
A potassium below the lab's range (MedlinePlus gives 3.5 to 5.1 mEq/L) points to low potassium, which can cause skipped beats; a very low level is dangerous for the heart. ¹⁰
Magnesium
A low magnesium is one of the causes of low potassium, so the two are read together when potassium is low. ¹⁰ See electrolytes explained.
Fasting glucose
A fasting glucose is a snapshot; a low reading, or a home meter reading below 70 mg/dL during symptoms in someone on diabetes medicines, fits low blood sugar. ¹²

These are things a symptom like this can be linked with, not a diagnosis. Several can sit together, and a clinician who knows your history puts them in order for you.

What do heart palpitations feel like, and what can each feeling point to?

How a palpitation feels gives a clinician clues, though feelings overlap and the recording decides. Bring your own description in plain words; it is one of the most useful things you can offer. Tapping the rhythm out on a table during an episode helps too: steady and fast, or irregular and chaotic.

What you notice	What it can be linked with	What helps sort it out
A thump, then a pause, as if the heart skipped	Extra (ectopic) beats, usually harmless ¹	ECG; a monitor if very frequent ²⁵
Fast and regular, after coffee, stress or exercise	A normal rhythm, sped up by a trigger ¹³	Looking at triggers; ECG if it keeps happening
Fluttering or irregular, sometimes at rest	AFib or another arrhythmia ⁷	ECG during the episode, or a monitor ⁶
Pounding with shakiness, sweating or hunger	Low blood sugar, in people on diabetes medicines ¹²	A glucose reading at the time ¹²
A fast heartbeat with weight loss and feeling hot	An overactive thyroid ¹¹	TSH and free T4 ¹³
Pounding with breathlessness on stairs and tiredness	Anemia ¹³	A blood count and ferritin ⁵

Why do I get heart palpitations at night?

Many people notice palpitations most when lying in bed. Cleveland Clinic explains that night-time palpitations "are just like daytime palpitations," but you may notice them more at night "because you're not busy or distracted." ³ An evening drink, a late coffee or a racing mind at bedtime can add to it. ¹

Two night-time patterns are worth raising with a clinician. Palpitations that wake you from sleep were one of the features linked with a higher chance of a heart cause in the research reviewed by American Family Physician in 2017. ⁵ And loud snoring, gasping or pauses in breathing at night point to sleep apnea, which raises the risk of AFib and is checked with a sleep study, not a blood test. ⁷ If poor sleep is part of the picture, see can't sleep, and for soaking sweats at night see night sweats.

Can anxiety cause palpitations, or is it my heart?

Both are possible, and they can happen together. Panic attacks bring a pounding heart, breathlessness and fear that can feel like a heart attack, and anxiety explains a large share of palpitations that get evaluated. ¹⁴ The risk is in assuming. The 2024 American Family Physician review says screening for psychological causes such as anxiety should be considered once no arrhythmia or heart cause is found, which means after the ECG, not instead of it. ⁶ If anxiety is part of it and you are having thoughts of harming yourself, call or text 988, the Suicide & Crisis Lifeline.

How are palpitations checked?

The first step is a 12-lead ECG: small sticky pads on the chest and limbs record the heart's electrical signal for about ten seconds. The 2024 review says "All patients with palpitations should have a 12-lead ECG as part of the initial evaluation." ⁶ Palpitations rarely happen on cue, so if the ECG is normal and the history still suggests a rhythm problem, a clinician may add a Holter monitor (worn for a day or more), an event monitor (worn for about 30 days for symptoms that come and go), or an implanted loop recorder for rare episodes with fainting. ⁵ Ambulatory ECG monitoring for 2 weeks gives the best yield for the cost when the cause is unclear. ⁶ An echocardiogram (an ultrasound of the heart) is added when structural heart disease is a concern, and a stress test when palpitations come with exercise. ⁵

What about my smartwatch?

Smartwatches and phone ECG devices can detect arrhythmias, mainly AFib, and a recording made during an episode can help a clinician. ⁶ They also miss short or symptom-free rhythm changes and have high false-positive rates, so a watch alert is a reason to see a clinician, not a diagnosis, and a quiet watch is not an all-clear. ⁶

The panel that checks these

Alongside the ECG, the blood tests that come first are a complete blood count (hemoglobin) for anemia, TSH for the thyroid, and potassium with kidney tests, because a 2017 primary care review lists those as the baseline. ⁵ Magnesium is added when potassium is low, ferritin when anemia is found, and glucose when low blood sugar is possible. Only the fasting glucose needs fasting, usually overnight. The ECG and heart rhythm entries are recordings, not blood tests.

Electrocardiogram (ECG)Extra beats (ectopic beats) · Heart rhythm problems such as AFib
Heart rhythmHeart rhythm problems such as AFib
TSHOveractive thyroid
Free T4Overactive thyroid
HemoglobinAnemia and low iron
FerritinAnemia and low iron
PotassiumLow potassium, magnesium or blood sugar
MagnesiumLow potassium, magnesium or blood sugar
Fasting glucoseLow potassium, magnesium or blood sugar

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Getting a useful test

Keep a log for two weeks: date, time, how long it lasted, what you were doing, and what you had drunk or taken. Tap the rhythm and note whether it was steady or irregular.
If palpitations come and go, ask whether you can get to a clinic or use a monitor during an episode; a recording during symptoms is worth more than any number of normal ones between them. ⁵
List every medicine and over-the-counter product with start dates, including cold and flu remedies with decongestants, diet pills and inhalers. ²³
Mention high-dose biotin (in many hair and nail supplements), which can make TSH look falsely low; the American Thyroid Association advises stopping it for at least 2 days before thyroid testing, a step to agree with your clinician. ¹⁴
Tell the clinician about any family history of sudden death at a young age or inherited heart conditions. ⁵
One result is a snapshot; see why trends beat single readings.

What may help

When palpitations have no medical cause, cutting the triggers is what helps most. None of these replaces checking the red flags above or an ECG for palpitations that are new or frequent.

Start with the everyday things

Cut back on caffeine, including energy drinks and pre-workout products, and see whether the palpitations ease. ¹
Drink less alcohol and stop smoking or vaping; both are listed triggers. ¹³
Protect your sleep: lack of sleep is a listed trigger, and coffee shortened sleep in the 2023 trial. ¹⁸
Stay hydrated, especially in heat, after exercise and with vomiting or diarrhea. ³¹⁰
Work on stress: in people with arrhythmias, a structured yoga practice of 45 to 60 minutes at least 3 days a week cut palpitation episodes in a systematic review. ⁶
Read labels on cold remedies for decongestants, and ask a pharmacist about alternatives. ²

No supplement is listed here. None has good evidence for palpitations, and potassium and magnesium, the two people most often reach for, are corrected by a clinician after a blood test, because the right amount depends on the level, kidney function and other medicines. Supplements support general wellness. They don't treat the causes above, and if a test finds one, treating that comes first. If you take medicines, are pregnant or have a health condition, check with your clinician before starting anything.

Questions to ask your clinician

Does my ECG show a normal rhythm, extra beats or something else?
Should I wear a monitor, and for how long, given how often the palpitations happen?
Do I need TSH, a blood count, potassium or magnesium checked?
Could any of my medicines or supplements be causing this?
Do I need an echocardiogram or a stress test?
Which signs would mean I should call 911 or come back sooner?

This page is general education, not medical advice or a diagnosis. Palpitations have many causes that can overlap, and the clinician who knows your history, examines you and reads your ECG is the one to put them in order.

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Citations

Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.

Heart palpitations: what they feel like, what causes them, and the tests that check them