Increased Heart Rate (Tachycardia): Causes and When to Worry

What counts as an increased heart rate

A normal resting heart rate for adults is 60 to 100 beats per minute. Tachycardia means a resting rate above 100. Children have faster normal rates: a newborn's heart rate can normally be 100 to 160 or more, and it slows gradually through childhood.

To measure your pulse, sit quietly for 5 minutes, then press two fingers on the inside of your wrist below the thumb. Count the beats for 30 seconds and double it. Note whether the rhythm is regular. Smartwatches are useful for trends, but an irregular reading should be confirmed with an ECG.

Heart rate increased: symptoms you may notice

• Palpitations: a pounding, racing or fluttering feeling in the chest or neck
• Dizziness or lightheadedness
• Shortness of breath
• Chest discomfort
• Tiredness or reduced ability to exercise
• Fainting or near-fainting

Some people feel nothing and find out only when their pulse is checked.

Causes of an increased heart rate

Normal responses (sinus tachycardia)

In most cases the heart's own pacemaker is simply speeding up for a reason. This is called sinus tachycardia. It rises gradually and falls gradually once the trigger goes. Triggers include:

• Exercise and physical exertion
• Stress, fear, excitement and anxiety
• Caffeine, energy drinks, nicotine, alcohol and alcohol withdrawal
• Fever: the heart rate rises by roughly 10 beats per minute for each 1 °C (1.8 °F) of temperature
• Pregnancy, when resting heart rate increases by about 10 to 20 beats per minute
• Pain

Medical causes

• Dehydration and blood loss: less blood volume means the heart pumps faster to maintain blood pressure.
• Anemia: fewer red blood cells carry less oxygen, so the heart compensates. Look for tiredness, pale skin and breathlessness.
• Hemolytic anemia: when red cells are destroyed faster than normal, as in hereditary spherocytosis, the combination of a fast heart rate, slight jaundice and dark urine is typical. Episodes often follow an infection.
• Infection and sepsis.
• Overactive thyroid: a fast pulse with weight loss, heat intolerance, tremor, sweating and anxiety.
• Pulmonary embolism: a blood clot in the lung often causes an unexplained fast heart rate, breathlessness and chest pain.
• Low blood sugar.
• Lung disease: asthma attacks, COPD flare-ups and pneumonia.
• Heart failure.
• Medicines and drugs: asthma inhalers (albuterol), decongestants, thyroid hormone in excess, some ADHD medicines, cocaine and amphetamines.
• POTS: in postural orthostatic tachycardia syndrome, the heart rate rises by 30 or more beats per minute on standing (40 or more in teenagers), with dizziness and fatigue, but without a large blood pressure drop.

Heart rhythm problems (arrhythmias)

When to worry about an increased heart rate

A fast heart rate is a concern when it happens at rest without an obvious reason, starts suddenly, is irregular, or comes with other symptoms. Call 911 or your local emergency number if it comes with chest pain, fainting, severe breathlessness or confusion. See a doctor promptly if your resting pulse is often over 100, or if episodes start and stop suddenly.

How doctors find the cause

• History: when it happens, how it starts and stops, triggers, caffeine, alcohol, medicines, family history of sudden death or arrhythmias.
• Examination: pulse, blood pressure lying and standing, temperature, thyroid, heart and lungs.
• ECG: the key test, ideally captured during an episode.
• Ambulatory monitoring: a Holter monitor for 24 to 48 hours, or an event monitor or patch for up to 2 weeks or longer.
• Blood tests: blood count, thyroid function, electrolytes, glucose, kidney function, and markers of hemolysis such as bilirubin when jaundice is present.
• Echocardiogram to look at heart structure.
• Exercise test and sometimes an electrophysiology study.

Treatment

Treatment targets the cause:

• Normal triggers: reduce caffeine, alcohol and nicotine, manage stress, stay hydrated, and treat fever.
• Medical causes: iron or other treatment for anemia, thyroid treatment, fluids for dehydration, antibiotics for infection, blood thinners for clots.
• SVT: vagal maneuvers, such as bearing down as if straining or a modified Valsalva maneuver taught by your doctor, can stop an episode. Medicines or a catheter ablation procedure can prevent them.
• Atrial fibrillation: medicines to control rate or rhythm, blood thinners to prevent stroke, and sometimes ablation.
• POTS: extra fluids and salt (if your doctor agrees), compression garments, graded exercise, and sometimes medicines.
• Dangerous rhythms: electrical cardioversion, and sometimes an implanted defibrillator.

Frequently asked questions

What are the symptoms of an increased heart rate?

Common symptoms are a pounding or racing feeling in the chest, dizziness, shortness of breath, chest discomfort, tiredness and sometimes fainting. Some people have no symptoms. Get emergency help if a fast heartbeat comes with chest pain, fainting, severe breathlessness or confusion.

What heart rate is too high at rest?

For adults, a resting heart rate above 100 beats per minute is called tachycardia. A resting rate over 120 that does not settle, or any rate over 150 without exercise, needs prompt medical assessment. During exercise, higher rates are normal and expected.

Can anxiety cause an increased heart rate?

Yes. Anxiety and panic release adrenaline, which speeds up the heart, often to 100 to 140 beats per minute. The rate rises and falls gradually with the anxiety. Because heart rhythm problems can feel similar, see a doctor if episodes start and stop suddenly or happen without stress.

Why does spherocytosis cause a fast heart rate, jaundice and dark urine?

In hereditary spherocytosis, red blood cells are fragile and are broken down early. This causes anemia, so the heart beats faster to deliver oxygen. Broken-down red cells release bilirubin, causing yellow skin or eyes, and dark urine. Flare-ups often follow infections and need medical review.

How can I lower my heart rate quickly?

If the cause is stress or exertion, sit down, breathe slowly and deeply, drink water and avoid caffeine. For diagnosed SVT, vagal maneuvers taught by your doctor can stop an episode. If a fast heart rate does not settle or comes with chest pain, fainting or breathlessness, seek urgent care.