A rapid heart rate, medically called tachycardia, is any resting heart rate above 100 beats per minute in adults. A normal resting heart rate falls between 60 and 100 bpm, so anything consistently above that upper threshold counts as fast. A rapid heart rate can be completely harmless, like after a cup of coffee or a stressful meeting, or it can signal an underlying problem that needs attention.
Normal Heart Rate by Age
What counts as “rapid” depends heavily on age. Children naturally have faster hearts than adults, so a rate that would be concerning in a 30-year-old is perfectly normal in a toddler.
- Newborns (birth to 4 weeks): 100 to 205 bpm
- Infants (4 weeks to 1 year): 100 to 180 bpm
- Toddlers (1 to 3 years): 98 to 140 bpm
- Preschoolers (3 to 5 years): 80 to 120 bpm
- School-age children (5 to 12 years): 75 to 118 bpm
- Adolescents and adults (13+): 60 to 100 bpm
These ranges apply when you’re awake and at rest. Sleep typically lowers your rate, while activity raises it. A heart rate of 130 bpm during a brisk walk is expected. A heart rate of 130 bpm while sitting on the couch watching TV is not.
Common Causes and Triggers
Many cases of rapid heart rate are temporary and tied to something obvious. Caffeine, nicotine, alcohol, dehydration, and stress all push the heart to beat faster. So does fever: for every degree your body temperature rises, your heart rate climbs along with it. Intense emotions, lack of sleep, and certain medications (including some cold and asthma drugs) can have the same effect.
Stimulant drugs like cocaine and methamphetamine are powerful triggers for dangerously fast heart rates. Even legal stimulants in high doses, like the caffeine in multiple energy drinks, can push your heart well past 100 bpm at rest.
When a rapid heart rate keeps coming back or doesn’t have an obvious trigger, it often points to an underlying condition. Some of the most common include:
- Overactive thyroid (hyperthyroidism): The thyroid floods the body with hormones that speed up metabolism, including heart rate.
- Anemia: When your blood carries fewer red blood cells, the heart compensates by pumping faster to deliver enough oxygen.
- Electrolyte imbalances: Abnormal levels of potassium, sodium, calcium, or magnesium can disrupt the heart’s electrical signals.
- Heart disease or prior heart attack: Damaged heart tissue can create faulty electrical pathways that trigger fast rhythms.
Types of Rapid Heart Rhythm
Not all fast heart rates are the same. The type depends on where the abnormal electrical signal originates in the heart, and that distinction matters because it affects both severity and treatment.
Supraventricular tachycardia (SVT) starts in the upper chambers of the heart. It tends to be less dangerous and is more common in younger, otherwise healthy people. Episodes often come on suddenly, last minutes to hours, and then stop just as abruptly. You might feel a fluttering in your chest or a pounding sensation in your neck.
Atrial fibrillation (AFib) is the most common sustained irregular heart rhythm. Instead of a steady fast beat, the upper chambers quiver chaotically, which can make the pulse feel irregular and unpredictable. AFib becomes more common with age and raises the risk of blood clots and stroke over time.
Ventricular tachycardia (VT) starts in the lower chambers and is the most serious type. It’s more likely to occur in older adults with existing heart disease. VT can deteriorate into ventricular fibrillation, a chaotic rhythm that causes the heart to stop pumping blood effectively. This is a cardiac arrest situation and a medical emergency.
What It Feels Like
Some people with a rapid heart rate feel nothing at all and only discover it during a routine check. Others experience noticeable symptoms that range from mildly annoying to frightening. The most common sensation is palpitations: an awareness of your heart beating hard, fast, or irregularly. You might describe it as a fluttering, pounding, or racing feeling in your chest.
When the heart beats fast enough that it can’t fill with blood properly between beats, other symptoms appear. These include dizziness or lightheadedness, shortness of breath, chest tightness or pain, and fatigue that seems out of proportion to what you’re doing. In more serious episodes, some people faint. Fainting during a rapid heart rate episode is a red flag, because it means the brain isn’t getting enough blood flow, and it warrants urgent evaluation.
How It’s Diagnosed
The core challenge with diagnosing a rapid heart rate is that it may not be happening when you’re sitting in a doctor’s office. That’s why the diagnostic process often involves several steps.
An electrocardiogram (EKG) is usually the first test. It takes about 10 seconds, involves sticking small electrode patches on your chest, and records the electrical pattern of your heartbeat. If your heart is racing during the test, an EKG can identify the type of tachycardia. But if your heart rate is normal at that moment, the results may look fine.
For episodes that come and go, portable monitors fill the gap. A Holter monitor is a small device you wear for 24 hours or more that continuously records your heart rhythm during normal daily life. An event monitor works differently: you wear it for days or weeks, but it only records when you activate it during symptoms or when it detects an abnormality automatically. Some smartwatches now offer basic EKG readings and can catch irregular rhythms at home, which gives your doctor useful data to work with.
Beyond rhythm monitoring, other tests help identify the cause. An echocardiogram uses ultrasound to create a moving image of your heart, showing how well it pumps and whether the valves work properly. A stress test monitors your heart while you walk on a treadmill or ride a stationary bike, revealing problems that only show up during exertion. If heart disease is suspected, a coronary angiogram threads a thin tube through a blood vessel to look for narrowed or blocked arteries. A tilt table test, where you’re strapped to a table that shifts from lying flat to upright, can determine whether your fast heart rate is causing fainting spells.
Treatment and Management
Treatment depends entirely on the type and cause. A rapid heart rate triggered by too much caffeine or a stressful week doesn’t need medical treatment. It needs less caffeine and better stress management. The same applies to dehydration, poor sleep, and nicotine: fix the trigger, and the heart rate usually normalizes.
For SVT episodes, many people learn a set of physical techniques called vagal maneuvers that can slow the heart in real time. These include bearing down as if having a bowel movement, splashing cold water on the face, or coughing forcefully. These techniques stimulate a nerve that helps regulate heart rate, and they work well enough that some people manage occasional episodes entirely on their own.
When a rapid heart rate is persistent or tied to a structural heart problem, treatment becomes more involved. Medications that slow the heart’s electrical signals are a first-line option for many types of tachycardia. For AFib specifically, blood-thinning medication is often prescribed to reduce stroke risk, because the irregular rhythm allows blood to pool and potentially clot in the heart.
A procedure called catheter ablation is an option for people whose rapid heart rate keeps recurring despite medication. A thin, flexible tube is guided into the heart through a blood vessel, and the small area of tissue responsible for the faulty electrical signal is destroyed with heat or cold. Success rates are high for many types of SVT, and the procedure often eliminates episodes entirely.
Symptoms That Need Immediate Attention
A brief episode of racing heart after a scare or a hard workout is normal. But certain combinations of symptoms suggest something more serious is happening. Chest pain alongside a rapid heart rate can indicate that the heart muscle isn’t getting enough oxygen. Fainting or near-fainting means blood flow to the brain has dropped significantly. Severe shortness of breath at rest, especially with a heart rate you can’t slow down, is another warning sign. If a rapid heart rate comes on suddenly and is accompanied by any of these, it warrants emergency care.