Rapid Pulse (Fast Heart Rate)

Normal pulse vs rapid pulse

Well-trained athletes often have resting rates in the 40s or 50s. A resting rate over 100 in an adult is tachycardia. A maximum heart rate during exercise is roughly 220 minus your age.

How to check your pulse

Place two fingers (not your thumb) on the inside of your wrist below the thumb, or on the side of your neck. Count beats for 30 seconds and multiply by 2. If the rhythm seems irregular, count for a full 60 seconds. Check after resting for at least 5 minutes. Smartwatches are generally accurate at rest, and many can record an ECG strip that is useful to show your doctor.

Causes of a rapid pulse

Normal or harmless causes

• exercise and physical exertion
• anxiety, stress, fear, excitement and pain
• caffeine, energy drinks, nicotine and alcohol
• pregnancy, when resting heart rate rises by 10 to 20 beats
• heat and high altitude

Medical causes (sinus tachycardia)

In these cases the heart's rhythm is normal but faster. This is sinus tachycardia, the body's response to a demand:

• Fever: the pulse rises about 10 beats per minute for each 1 °C (1.8 °F) of fever
• Dehydration and blood loss
• Anemia: the heart pumps faster to deliver oxygen
• Hyperthyroidism
• Low blood sugar
• Infection and sepsis
• Lung problems: pulmonary embolism, pneumonia, asthma attack, COPD
• Heart failure
• Medicines and drugs: decongestants, asthma inhalers (albuterol), thyroid hormone, some antidepressants, ADHD stimulants, cocaine and amphetamines
• Withdrawal from alcohol, benzodiazepines or beta-blockers

Heart rhythm problems

Postural tachycardia (POTS)

In postural orthostatic tachycardia syndrome, the heart rate rises by 30 or more beats per minute within 10 minutes of standing (40 or more in teenagers), with lightheadedness, fatigue and brain fog, without a drop in blood pressure. It is most common in young women and sometimes follows a viral illness.

Symptoms that may come with a rapid pulse

• pounding or fluttering in the chest (heart palpitations)
• lightheadedness or dizziness
• shortness of breath
• chest discomfort
• tiredness and reduced exercise tolerance
• fainting

How doctors find the cause

A doctor will ask when the fast heartbeat happens, whether it starts suddenly, whether it is regular, what triggers it, and about caffeine, alcohol, medicines and drugs, weight change, and family history of heart rhythm problems or sudden death.

Tests may include:

• ECG: a 12-lead tracing of the heart rhythm
• Heart monitor: a 24-hour to 2-week patch, or an event recorder for occasional episodes
• Blood tests: blood count, thyroid function, electrolytes, glucose, kidney function
• Echocardiogram: ultrasound of heart structure and function
• Stand test or tilt-table test for POTS
• Exercise test for symptoms with exertion

Treatment

Treatment depends on the cause:

• Sinus tachycardia: treat the trigger, such as fever, dehydration, anemia, thyroid or pain.
• SVT: vagal maneuvers (such as bearing down as if straining, or the modified Valsalva maneuver taught by a doctor) can stop an episode. Medicines or a catheter ablation procedure prevent recurrences.
• Atrial fibrillation: rate-control or rhythm-control medicines, anticoagulants to prevent stroke, cardioversion or ablation.
• POTS: more fluids and salt (if advised), compression garments, graded exercise, and sometimes medicines.
• Ventricular arrhythmias: specialist treatment, sometimes an implanted defibrillator.

Self-care for a fast heartbeat

• Cut back on caffeine, energy drinks, alcohol and nicotine.
• Stay well hydrated.
• Avoid decongestants if they trigger palpitations.
• Practice slow breathing: breathe in for 4 seconds and out for 6 seconds for a few minutes.
• Get regular sleep and exercise.

Frequently asked questions

What is a dangerously high heart rate?

There is no single cutoff, but a resting heart rate above about 150, or any fast rate with chest pain, fainting, severe breathlessness or confusion, needs emergency care. A resting rate repeatedly above 100 without an obvious reason should be checked by a doctor.

Why is my heart rate high when resting?

Common reasons are anxiety, caffeine, dehydration, fever, poor sleep, alcohol, anemia, an overactive thyroid and medicines such as decongestants or inhalers. Heart rhythm problems are less common but important. An ECG and basic blood tests usually find the cause.

Can anxiety cause a rapid pulse?

Yes. Anxiety releases adrenaline, which speeds the heart, often to 100 to 130 beats per minute. It usually slows within minutes as anxiety settles. A pulse that starts and stops suddenly, is irregular or very fast should be checked to rule out a rhythm problem.

Does dehydration cause a fast heart rate?

Yes. Losing fluid lowers blood volume, so the heart beats faster to maintain blood pressure. It is often worse when standing. Drinking fluids usually helps. Severe dehydration from vomiting or diarrhea with dizziness or fainting needs medical care.

How can I lower my heart rate quickly?

Sit or lie down, breathe slowly, and drink water. Avoid caffeine and nicotine. For known SVT, a vagal maneuver your doctor has taught you may stop it. If the rate stays high, or you have chest pain, fainting or breathlessness, seek emergency care.