Why is my heart rate high?

Common causes of a fast heart rate include anxiety, strenuous exercise, fever, pain and some medicines.^[1] At rest, a rate over 100 beats per minute is called tachycardia.^[1] Call 911 if your heart rate is suddenly very high or very low for you, especially with chest pain, shortness of breath, dizziness or fainting.^[14]

What counts as a high heart rate?

A normal resting heart rate for adults is 60 to 100 bpm.^[1] A resting rate over 100 bpm is tachycardia.^[1] During exercise, a faster rate is expected. The concern is a fast rate when you are at rest.^[1] For what is typical, read what a good resting heart rate is.

The AHA describes several types of fast heart rate.^[1] Atrial fibrillation, an irregular rhythm, can also bring rapid palpitations.^[16]

Everyday causes

When you are scared, very emotional, anxious or exercising, your heart may speed up for a short time. That is sinus tachycardia, and it goes away when you calm down or rest.^[5] Many of the lists below are about palpitations, when your heartbeat becomes more noticeable. Palpitations are not always a fast rate, and they are common and not usually a sign of anything serious.^[3]

• Exercise. Strenuous exercise is a common cause.^[3]
• Stress, anxiety, panic or fear.^[4]
• Lack of sleep.^[3]
• Caffeine and nicotine.^[4]
• Alcohol, especially heavy drinking.^[4]
• Fever.^[4] A fast pulse may also signal an infection or dehydration.^[2]
• Medicines. Decongestants such as phenylephrine or pseudoephedrine, and diet pills.^[4] Over-the-counter medicines for asthma, colds and allergies can trigger SVT.^[1] Some medicines for asthma, high blood pressure or heart problems can cause an abnormal rhythm.^[4]
• Pregnancy and menopause.^[3]
• Stimulant drugs such as cocaine or methamphetamine.^[4]

What the research says about alcohol, caffeine, fever and pregnancy

Alcohol. At the 2015 Munich Octoberfest, researchers ran a phone-based ECG on 3,028 people and measured their breath alcohol.^[10] Sinus tachycardia showed up in 25.9% of them, and higher breath alcohol went with higher odds of it.^[10] This was a snapshot, so it shows a link, not proof that alcohol caused each case.

Caffeine. Health pages list caffeine as a trigger for palpitations.^[4] The evidence on extra beats is mixed. In a trial of 100 adults, days with coffee did not bring significantly more extra beats from the upper chambers.^[11] They did bring more extra beats from the lower chambers: 154 a day, compared with 102 on days without caffeine.^[11]

Fever. In children seen in UK emergency departments, heart rate rose by about 10 bpm for each degree Celsius of body temperature.^[13] That figure comes from children, so it may not hold for adults.

Pregnancy. A review of pregnancy changes puts the rise in the mother's heart rate at 10 to 20 bpm.^[12]

Medical causes worth knowing

Less common causes include anemia, infection and an overactive thyroid.^[1]

• Overactive thyroid (hyperthyroidism). Symptoms can include a rapid or irregular heartbeat, weight loss despite a bigger appetite, nervousness and trouble sleeping.^[7]
• Low blood sugar. In people with diabetes, low blood glucose can make you shaky, hungry or dizzy, and your heart may beat too fast or not steadily.^[8]
• Postural orthostatic tachycardia syndrome (POTS). Heart rate may rise by more than 30 bpm, or go above 120 bpm, within 10 minutes of standing.^[9] In teens, the threshold is a rise of at least 40 bpm.^[9]
• Infections and blood chemistry. Viral infections such as flu or COVID-19 make heart rhythm problems more likely.^[6] NHLBI also lists dehydration and low electrolyte levels as triggers.^[6]
• Heart rhythm problems. Arrhythmias and other heart problems such as heart valve disease can cause palpitations.^[3]

For sinus tachycardia, the AHA says treatment aims at the cause. Slowing the heart rate on its own could do more harm if the fast rate is a symptom of a bigger problem.^[1]

Reading a standing heart rate

Heart rate may go up a little when you first stand, then settle within a few minutes.^[14] The worked example shows how a normal rise compares with the size of rise described in POTS. It explains the numbers; it is not a test you can diagnose yourself with.

What to do when you see a high number

1. 1Check that the number is real. A wrist tracker may not always match an ECG, mostly during activity and when your heart is beating fast, though other studies found the difference small.^[17] Count your pulse at the wrist for 30 seconds and double it.^[2]
2. 2Rest, then check again. To find a resting rate, you need to have been resting for at least 10 minutes.^[2]
3. 3Think about the last few hours: exercise, stress, coffee, alcohol, a short night, a new medicine, or feeling unwell.^{[3, 4]}
4. 4If palpitations are not caused by a health condition, avoiding triggers such as stress, smoking, caffeine and alcohol can help.^[3]

When to talk to a clinician