Tachycardia is a resting heart rate above 100 beats per minute, and what you should do about it depends on how you feel in the moment. If you’re experiencing chest pain, fainting, severe dizziness, or shortness of breath alongside a racing heart, that’s a medical emergency. If you’re conscious, stable, and just dealing with an uncomfortably fast heartbeat, there are techniques you can try right now to slow it down, along with longer-term strategies to reduce how often episodes happen.
When a Racing Heart Is an Emergency
Not every episode of tachycardia is dangerous, but certain symptoms alongside a fast heart rate mean you need emergency help immediately:
- Chest pain or tightness
- Fainting or nearly fainting
- Severe shortness of breath
- Sudden weakness
- Persistent dizziness or lightheadedness
One form of tachycardia, called ventricular fibrillation, is life-threatening and requires immediate intervention. In this condition the heart’s lower chambers quiver chaotically instead of pumping blood. If someone collapses with no pulse, call emergency services and begin CPR. For episodes where you feel your heart racing but you’re alert, breathing normally, and not in pain, the techniques below are your first line of response.
Vagal Maneuvers You Can Try Right Now
Vagal maneuvers work by stimulating the vagus nerve, which runs from your brain to your abdomen and acts as a brake on your heart rate. These techniques are most effective for a type of fast rhythm called supraventricular tachycardia (SVT), where the rapid signals originate above the heart’s lower chambers. They won’t help every kind of tachycardia, but they’re safe to attempt while you assess the situation.
The Valsalva Maneuver
Lie on your back, take a deep breath, then try to push the air out hard while keeping your mouth and nose closed. It should feel like blowing into a blocked straw. Hold that straining effort for 10 to 30 seconds. A modified version of this technique works significantly better: after straining for 15 seconds while sitting up, immediately lie flat and raise your legs in the air (or pull your knees to your chest) for another 30 to 45 seconds. A clinical trial published in The Lancet found the modified version restored normal heart rhythm in 43% of patients, compared to just 17% with the standard approach. That’s a meaningful difference for something you can do at home.
The Diving Reflex
This triggers the same response your body has when submerged in cold water. While sitting, take several deep breaths, hold the last one, then plunge your entire face into a bowl of ice water. Keep it submerged as long as you can tolerate. If you don’t have a bowl handy, pressing a bag of ice or a soaking-cold wet towel firmly against your face works as an alternative. The cold activates a reflex that rapidly slows the heart.
Other Simple Techniques
Bearing down as if you’re having a bowel movement stimulates the vagus nerve through similar pressure changes in your chest. Coughing forcefully can also help. For children, a commonly used approach is having them blow on their thumb without letting any air escape. One technique called carotid sinus massage, where pressure is applied to the side of the neck, should only be performed by a healthcare provider because of the risk of dislodging plaque in the artery.
Lifestyle Changes That Reduce Episodes
If you’re dealing with recurring tachycardia, daily habits play a real role in how often episodes strike. Caffeine is one of the most common triggers. It directly increases heart rate and raises the risk of abnormal rhythms. You don’t necessarily need to eliminate it entirely, but cutting back or switching to lower-caffeine options is worth trying to see if your episodes become less frequent.
Alcohol is another well-established trigger. It raises blood pressure, which can set off fast rhythms, particularly in the heart’s lower chambers. General guidance is to limit intake to one drink per day for women and two for men, though some people with tachycardia find that even moderate drinking provokes episodes. Nicotine, stimulant medications, and recreational drugs can all push heart rate up as well.
Dehydration and poor sleep are easy to overlook but genuinely matter. When your blood volume drops from not drinking enough water, your heart compensates by beating faster. Sleep deprivation raises baseline stress hormones that keep your heart rate elevated. Regular aerobic exercise, somewhat counterintuitively, lowers your resting heart rate over time by making your heart more efficient at pumping blood.
Electrolytes and Heart Rhythm
Your heart’s electrical system depends on a precise balance of minerals, and two stand out: potassium and magnesium. A significant drop in blood potassium can cause abnormal heart rhythms, and in severe cases, can even cause the heart to stop. Low magnesium often drags potassium levels down with it, creating a compounding problem.
Common causes of low potassium include diuretics (water pills), prolonged vomiting or diarrhea, heavy sweating, and not eating enough potassium-rich foods like bananas, potatoes, and leafy greens. If you take a diuretic for blood pressure, your prescriber may add a potassium supplement to compensate. Getting these levels checked through a simple blood test is worthwhile if you’re experiencing recurring episodes, since correcting the deficiency with supplements often resolves the rhythm disturbance entirely.
How Tachycardia Gets Diagnosed
A standard electrocardiogram (ECG) is the first test, recording your heart’s electrical activity through sticky patches placed on your chest. It takes only a few minutes and shows whether your heart rhythm is abnormal at that moment. The challenge is that many people with tachycardia have episodes that come and go, so a normal ECG in the office doesn’t rule anything out.
For intermittent episodes, you may be asked to wear a Holter monitor, a portable ECG device that records continuously for one to several days while you go about your normal life. If your episodes are even less frequent, an event monitor that you wear for weeks and activate when symptoms occur captures what’s happening during the actual episode. A tilt table test, where you’re strapped to a table that shifts from lying flat to standing upright, helps evaluate whether position changes trigger your symptoms by watching how your heart and nervous system respond in real time.
Smartwatches have become a surprisingly useful screening tool. A study involving patients with known fast heart rhythms found that the Apple Watch and Samsung Galaxy Gear detected heart rates during tachycardia episodes (ranging from 108 to 228 bpm) with 100% accuracy within 10 beats per minute. The Fitbit Charge 2 was accurate 88% of the time. These devices aren’t replacements for medical ECGs, but they can capture heart rate data during an episode that you can show your doctor, which is genuinely helpful for diagnosis.
Medications for Ongoing Management
When lifestyle changes and vagal maneuvers aren’t enough, medications can keep heart rate under control. The two most common classes are beta-blockers, which reduce the effect of adrenaline on the heart, and calcium channel blockers, which slow electrical signals through the heart and lower heart rate. Both are taken daily for prevention or, in some cases, used as needed when an episode starts.
If you’re prescribed a calcium channel blocker, one practical detail worth knowing: grapefruit and grapefruit juice interfere with how certain versions of these medications are processed in your body, potentially causing dangerous changes in heart rate and blood pressure. Your pharmacist will flag this, but it catches people off guard. Anti-arrhythmic medications that directly stabilize the heart’s electrical activity are another option for specific types of tachycardia, though they tend to have more side effects than beta-blockers or calcium channel blockers.
Catheter Ablation for Lasting Results
For people whose tachycardia keeps recurring despite medication, or who prefer not to take daily pills, catheter ablation offers a more permanent fix. A thin, flexible tube is threaded through a blood vessel (usually in the groin) up to the heart, where it delivers targeted energy to destroy the tiny cluster of cells causing the abnormal electrical signals. The procedure typically takes a few hours, and most people go home the same day or the next morning.
Success rates depend on the type of tachycardia. For SVT, ablation works 90% to 95% of the time, making it one of the most reliable procedures in cardiology. For atrial fibrillation, atrial tachycardia, and ventricular tachycardia, success rates range from 60% to 80%, and some people need a second procedure. Ablation is generally recommended when medications haven’t controlled the rhythm, when side effects from medication are a problem, or when there’s a risk of sudden cardiac arrest.