Fast heart rate (more than 100 beats per minute) without obvious cause

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Fast heart rate (more than 100 beats per minute) without obvious cause

A normal heart rate for a healthy adult is between 60 and 100 beats per minute. Heart rates of more than 100 beats per minute (tachycardia) can be caused by:

• Exercise or stress. This fast heart rate usually returns to normal range (60 to 100 beats per minute) with rest and relaxation.
• Illnesses that cause fever. When the cause of the fever goes away, the heart rate usually returns to normal.
• Dehydration. When the dehydration is treated, the heart rate usually returns to normal.
• Medication side effects, especially asthma medications.
• Heavy smoking, alcohol, or too much caffeine or other stimulants, such as diet pills. Stopping the use of tobacco, alcohol, caffeine, or other stimulants may help your heart rate return to normal.
• Cocaine, amphetamines, and methamphetamines.

Babies and children younger than 2 years old have higher heart rates because their body metabolism is faster. Heart rates decrease as children grow, and usually by the teen years the heart rate is in the same range as an adult's.

A new fast heart rate may be caused by a more serious health problem. Heart disease or other medical conditions may sometimes cause a fast heart rate. A fast heart rate may cause palpitations, dizziness, lightheadedness, or fainting. Atrial fibrillation is the most common type of fast heartbeat. It causes the heart's upper chambers to beat irregularly, reducing blood flow to the heart muscle and to the rest of the body. Atrial fibrillation increases your chance of having a stroke or a blood clot in the lungs (pulmonary embolism).

If you have heart disease, heart failure, or have had a heart attack, it is especially important to understand how serious a fast heart rate can be. This is especially true if it occurs with shortness of breath when you are resting or after mild exertion. Call your health professional if you have a sudden change in your usual heart rate or rhythm.

Credits

Last updated:	April 27, 2007
Author:	Jan Nissl, RN, BS
Reviewed By:	William M. Green, MD - Emergency Medicine, H. Michael O'Connor, MD - Emergency Medicine
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer