A taser can deliver a serious shock to a person’s nervous system. In some cases, it can lead to potentially life-threatening heart complications.

Known as a conducted energy weapon (CEW), the taser shoots two small darts connected to the device with thin wires that can deliver up to 50,000 volts of electric shock to a person’s nervous system.

The shock temporarily incapacitates the person, so law enforcement agencies often use them to apprehend suspects and civilians seeking greater self-defense. The effects of a taser usually wear off in minutes without harmful, long-term consequences, but the weapons have been known to trigger severe heart complications — even in otherwise healthy people.

This article will explain the possible impacts a taser can have on the heart, how serious that may be for someone with pre-existing heart health issues or even for someone who’s experienced a heart attack.

When a taser strike causes a heart complication, it’s usually cardiac arrest, not a heart attack. Though some people often treat “heart attack” and “cardiac arrest” as synonymous, they are two different cardiac events. Cardiologists consider a heart attack primarily a “plumbing” complication, while cardiac arrest is an electrical complication.

Most heart attacks occur when one or more coronary arteries experience a blockage, preventing the heart muscle from getting adequate blood flow. As a result, heart muscle tissue begins to die. Cardiac arrest means the heart suddenly stops pumping, usually due to a disturbance within the heart’s electrical system that regulates the beating of your heart.

Because tasers act directly on the nervous system, they are most likely to trigger a heart rhythm disturbance (arrhythmia) or cardiac arrest rather than a heart attack.

A 2014 research review suggested that tasers can cause a life threatening arrhythmia called ventricular fibrillation (VF), even in physically healthy people with no prior heart conditions. VF means the heart’s lower chambers (ventricles) beat in an atypical rhythm, reducing the heart’s ability to pump enough blood to the body consistently and raising the risk of cardiac arrest.

Aside from the risk of a taser encounter leading to serious arrhythmia and cardiac arrest, one other effect can be an injury from falling. A person who experiences the taser strike may fall to the ground and hit their head or injure another body part.

While they both use electrical energy to incapacitate a person, a stun gun differs from a taser in some important ways. A stun gun, for example, requires people to be in close physical contact with each other, while a person can use a taser within 35 feet of another person.

A stun gun also uses a battery to produce the energy to discharge a powerful electrical impulse. A person can use it repeatedly as long as they charge the battery. A taser relies on a cartridge containing darts and wires. A person can use one cartridge for a few “shots” and replace it.

Neither a taser nor a stun gun can stop a heart attack or cardiac arrest.

However, electrical impulses from a defibrillator can sometimes restore healthy electrical activity in a heart experiencing cardiac arrest. But a defibrillator emits only about 200 to 1,000 volts, which is still quite high but less than a taser or a standard stun gun.

Never use a stun gun to treat a person in cardiac distress.

A small 2021 review about CEW exposure suggested that the risk of serious health consequences is low, but the researchers acknowledged that most subjects in these studies were healthy adults.

However, even if no lingering health complications emerge from a taser encounter, some medical attention is sometimes necessary.

For example, a taser’s darts can lodge in the skin, and medical professionals must remove them carefully.

A 2019 report also suggested that while there are no set guidelines on performing tests or screenings on a person injured by a taser, such evaluations may be necessary if the individual has symptoms such as a racing heart, loss of consciousness, or other signs of distress.

A history of heart complications may also indicate that a more thorough evaluation is appropriate.

Tests may include an electrocardiogram to assess the heart’s electrical activity and other cardiac monitoring.

In an emergency situation, if a person appears to go into cardiac arrest, performing cardiopulmonary resuscitation (CPR) until a defibrillator is available could save a life. CPR may be able to keep the heart going temporarily. But a defibrillator and treatment in a hospital emergency department are usually necessary for an individual to have a chance of surviving cardiac arrest.

Despite the occasional news report of a person on the receiving end of a taser experiencing serious heart complications, these encounters seldom lead to severe medical concerns. Still, there is a slight risk of the taser leading to a harmful heart rhythm disturbance or the person affected by the taser falling and experiencing a fracture or another injury.

It’s important to note that a taser or stun gun can affect the body’s nervous system, which can then affect the heart’s electrical activity. CPR or defibrillation is usually the only immediate means of restoring a healthy heart rhythm if cardiac arrest sets in.