A conducted electrical weapon, commonly known by the brand name TASER, delivers a pulsed electrical current that overrides your voluntary muscle control for as long as the device is active. The experience is intense but brief: your muscles lock up involuntarily, you lose the ability to move on your own, and most people fall to the ground. What happens internally is more layered than the visible collapse, involving your muscles, blood chemistry, breathing, heart, and sometimes your bones.
The Immediate Lockup
When the two barbed probes make contact with your body, the device sends rapid electrical pulses between them. These pulses hijack the electrical signals your brain normally sends to your muscles, causing widespread involuntary contraction. The result is what researchers and manufacturers call “neuromuscular incapacitation,” and it feels like every muscle between the two probes clenches at once. You cannot override it with willpower. Most people describe the sensation as overwhelming and painful, though the pain is tied to the active discharge and fades quickly once the current stops.
A standard deployment lasts five seconds. During that window, you are essentially paralyzed. A study measuring how quickly people could perform a simple task found that only 2 out of 32 subjects managed to press a button during the exposure, and even those two took several seconds longer than normal. Once the current stopped, subjects recovered their ability to act within about one to two seconds on average, a response time that was statistically no different from their normal reaction speed to an audio cue.1PubMed. Incapacitation recovery times from a conductive electrical weapon exposure The incapacitation, in other words, is almost entirely confined to the seconds the device is firing.
What Your Muscles Go Through
The forced contraction is not gentle. Every skeletal muscle in the current path fires at once, and the force generated can be extreme. Case reports document fractures caused purely by the violence of these contractions, not by falling. In one case, a 23-year-old man sustained compression fractures of three thoracic vertebrae from a single deployment.2PubMed Central. Thoracic Compression Fracture as a Result of Taser Discharge Other reports describe femoral neck fractures, joint dislocations, and tendon ruptures from the sheer force of electrically induced muscle contraction.3Arthroplasty Today. TASER-Induced Femoral Neck Fracture Following Hip Resurfacing Arthroplasty in a Law Enforcement Officer These injuries are rare, but they illustrate just how powerful the involuntary contractions can be, sometimes exceeding what the skeleton can withstand.
Beyond acute structural damage, the sudden mass contraction can injure the muscle tissue itself. When muscle fibers are damaged, they release a protein called creatine kinase (CK) into the bloodstream. Research on electronic control device exposures shows a modest rise in CK levels afterward, with the increase tending to be larger when someone receives multiple contact points or repeated exposures rather than a single standard deployment.4PubMed. The effect of an electronic control device on muscle injury as determined by creatine kinase enzyme In most healthy people, this amount of muscle damage is clinically insignificant. But in some cases it escalates to rhabdomyolysis, a condition where so much muscle protein floods the bloodstream that it can overwhelm the kidneys.
How often does that happen? One early estimate found roughly a 1% incidence of rhabdomyolysis among people brought to emergency departments after being tased with older-generation devices.5PubMed. Two patients subdued with a TASER device: cases and review of complications Most cases have been mild, but severe rhabdomyolysis with kidney failure has been documented as well.6PubMed Central. TASER Electronic Control Device-Induced Rhabdomyolysis and Renal Failure: A Case Report The complicating factor is that people who get tased in the real world are often already physically stressed, agitated, or under the influence of drugs, all of which independently raise the risk of rhabdomyolysis. No study has been able to isolate the device as the sole cause in these patients.
How Your Blood Chemistry Shifts
The forced whole-body contraction is essentially the equivalent of a sudden, maximal burst of exercise. Your muscles burn through their fuel anaerobically, which produces lactic acid. In animal studies, blood lactate climbed sharply after repeated exposures and took over an hour to return to baseline, while blood pH dropped significantly for a similar period.7PubMed. Acidosis, lactate, electrolytes, muscle enzymes, and other factors in the blood of Sus scrofa following repeated TASER exposures
Human studies largely confirm the same pattern but suggest the metabolic hit from a standard five-second exposure is modest and resolves on its own. In one study, volunteers exercised to exhaustion and then received a 15-second exposure. Their blood lactate rose from about 8.4 after exercise to about 9.9 after the device exposure, and their blood pH dipped slightly further. By 24 hours, everything had returned to normal.8PubMed. Prolonged TASER use on exhausted humans does not worsen markers of acidosis Researchers who have reviewed the data across multiple studies have concluded that the lactate increase from a short-duration exposure is not, by itself, clinically dangerous.9PubMed. Blood lactate concentration after exposure to conducted energy weapons (including TASER devices): is it clinically relevant?
That caveat “by itself” matters. In a controlled lab setting with a healthy volunteer, the metabolic disturbance is trivial. In a real-world scenario where someone is already in a state of extreme exertion, intoxication, or excited delirium, the added metabolic burden sits on top of an already stressed system. The studies that exist simply do not reflect those conditions well.
What Happens to Your Breathing
Because the electrical pulses cause your chest muscles, diaphragm, and abdominal muscles to contract simultaneously, your ability to breathe is temporarily compromised during the exposure. Research on law enforcement trainees found a significant decrease in both inspiratory and expiratory lung volumes during the five-second discharge. Interestingly, inspiratory volume dropped more than expiratory volume, meaning subjects were more limited in their ability to breathe in than to breathe out.10PubMed Central. Respiratory and Cardiovascular Response during Electronic Control Device Exposure in Law Enforcement Trainees
Once the device stopped firing, subjects quickly compensated with larger-than-normal breaths, and their breathing volumes exceeded their pre-exposure baseline in the immediate aftermath. In practice, this means a standard five-second deployment causes a brief period of restricted breathing followed by a natural recovery. The concern grows with longer or repeated deployments, where the cumulative time without adequate ventilation could become more significant, particularly in someone who is already struggling to breathe due to physical exertion, obesity, prone positioning, or respiratory conditions.
The Cardiac Question
Whether a TASER can stop your heart is the most debated question in this space, and the honest answer is: it is very unlikely with a standard deployment, but the risk is not zero. The primary danger is ventricular fibrillation, a chaotic heart rhythm that prevents the heart from pumping blood. For the device to trigger this, the electrical current needs to reach the heart at sufficient strength.
In pig studies, ventricular fibrillation occurred when the dart landed close enough to the heart, with the critical dart-to-heart distance averaging about 17 millimeters for the first event. In humans, the distance from the skin surface to the heart ranges from about 10 to 57 millimeters depending on body composition and anatomy, meaning that a dart could theoretically land close enough. Researchers estimated the probability of a single dart randomly landing in the precise spot over the ventricle and causing fibrillation at roughly 0.017%, an extremely low but nonzero figure.11PubMed. Taser dart-to-heart distance that causes ventricular fibrillation in pigs
A separate modeling study using a detailed anatomical model of an adult man found that, in worst-case dart placements, cardiac exposure could reach levels associated with a 30% fibrillation risk. But the overall risk was reduced considerably once you factor in the low probability of a dart actually hitting that precise location.12PubMed. Cardiac fibrillation risk of TASER X-26 dart mode application The research consensus describes the cardiac fibrillation risk as small but not negligible, a characterization that both studies agree on.
People with Pacemakers and Defibrillators
Given the electrical nature of TASERs, you might expect them to damage implanted cardiac devices like pacemakers and defibrillators. The research is surprisingly reassuring on this point, though with some caveats. A study testing standard five-second discharges on implanted devices found that the pacemakers and defibrillators continued to function normally afterward, with no significant changes in pacing thresholds, battery voltage, or lead integrity.13PubMed. Do electrical stun guns (TASER-X26) affect the functional integrity of implantable pacemakers and defibrillators?
The devices do notice the TASER discharge, however. Implanted defibrillators may interpret the rapid electrical pulses as a dangerous heart rhythm and begin charging to deliver a corrective shock. In the studies, though, the standard five-second exposure ended before the defibrillator could actually deliver that shock, so no inappropriate therapy was delivered.14PubMed. TASER conducted electrical weapons and implanted pacemakers and defibrillators Pacemakers can also experience oversensing, temporarily inhibiting their pacing during the discharge. A longer exposure or repeated cycles could, in theory, push past these safety margins. More recent testing confirmed that oversensing occurs and that the type of stun device used, the device’s placement, and the distance from the application site all influence how likely it is. No permanent damage to any device was observed.15Heart Rhythm. Effects of handheld electro-shockers on cardiac implantable electronic devices
Injuries from Falling
One of the most underappreciated risks of being tased has nothing to do with electricity. When you lose all voluntary muscle control, you fall, and you fall without any ability to catch yourself. On a soft surface that may be harmless. On concrete, stairs, or near sharp objects, the consequences can be severe. A review identified 16 probable cases of fatal traumatic brain injury caused by falls during electronic control weapon use, out of roughly three million field deployments. That works out to about five fatal brain injuries per million uses, a rate that the researchers noted actually exceeded the estimated risk of death from the electrical discharge itself.16PubMed. Fatal traumatic brain injury with electrical weapon falls
This is a genuinely important finding that often gets overlooked in debates about TASER safety. The conversation tends to focus on whether the electricity can kill you directly, but the fall is statistically more dangerous. Head injuries, broken wrists, facial lacerations, and dental damage from unbraced falls onto hard surfaces are among the most common real-world injuries associated with TASER deployments.
When a Probe Hits the Eye
The two barbed probes are small projectiles fired at high speed, and they do not always land where intended. When a probe strikes the eye, the consequences can be devastating. A review of the literature found 38 documented cases of ocular TASER injuries. In most, the mechanism was direct penetration of the probe into the eye. Cases involving probe penetration showed the most severe outcomes, with poor visual prognosis.17PubMed. Taser-Related Ocular Injuries: A Review of the Literature and Medico-Legal Implications
Reported injuries include retinal detachment after the probe perforated the front of the eye socket, globe perforation with tissue prolapse, and cataract formation from electrical discharge across the eye.18PubMed Central. Ocular TASER Probe Injury Managed with Primary Evisceration Cataracts can also develop as a longer-term complication, consistent with what is seen after other types of electrical injury.19Trauma Case Reports. Ocular manifestations of TASER-induced trauma Some of these cases have resulted in permanent loss of the eye. While ocular injuries are rare given the millions of deployments worldwide, they represent one of the most serious categories of TASER-related harm.
The Stress Response
Being tased is psychologically terrifying in addition to being painful, so you might expect a massive hormonal stress response. The research tells a more nuanced story. A study comparing the neuroendocrine effects of TASER exposure against other common use-of-force scenarios, including defensive tactics drills and pepper spray, found that the TASER was not more activating of the stress response than the alternatives. Stress hormones like cortisol and the enzyme alpha-amylase, a marker of sympathetic nervous system activation, rose more in response to physical struggle and pepper spray exposure than to the electrical device. This suggests that while the experience is certainly stressful, the body’s hormonal reaction is driven more by the overall physical confrontation than by the electrical current itself.
How the Research Falls Short
A major limitation runs through nearly all TASER safety research, and it is worth understanding. A large review of the evidence found that across the studies available, most were performed on healthy, physically fit individuals such as police officers, in controlled laboratory settings, using the standard five-second exposure duration. Few or no acute health problems were reported apart from the dart wounds themselves, and no long-term outcomes were studied at all.20PubMed Central. Risks of Conducted Electrical Weapon Exposure
The gap between these study populations and the people who actually get tased in the field is enormous. Real-world subjects are often in acute mental health crises, under the influence of stimulants or alcohol, physically exhausted from running or fighting, and sometimes have underlying heart conditions they may not know about. The controlled studies tell us that a healthy body tolerates a five-second discharge well. They tell us much less about what happens to a body that is already at its physiological edge.
One somewhat counterintuitive finding from animal research addresses one piece of this puzzle. A study testing whether cocaine intoxication increased vulnerability to TASER-induced ventricular fibrillation found the opposite: cocaine actually raised the threshold for inducing fibrillation, requiring stronger discharges to trigger it. No heart damage markers were elevated after the exposures.21PubMed. Effects of cocaine intoxication on the threshold for stun gun induction of ventricular fibrillation That result, however, comes from a controlled animal model and does not account for the full picture of what cocaine does to a human heart during a chaotic real-world encounter. The finding is interesting but should not be interpreted as meaning cocaine use makes TASER exposure safer overall.
The Probe Wounds Themselves
Each TASER dart has a small barbed tip designed to embed in the skin and maintain electrical contact. The probes typically penetrate a few millimeters to about a centimeter, depending on clothing and body composition. The resulting puncture wound is small, roughly comparable to a fishhook injury. In most cases, the wounds are superficial and heal without complications once the probes are removed, which usually requires a firm pull or, in some cases, a small incision if the barb is deeply embedded.
The more meaningful skin effect is a localized burn at the probe site from the electrical current. These burns are usually minor, presenting as small reddened marks that resolve within days. More prolonged exposures can produce more pronounced burns, though this has been studied less thoroughly with newer-generation devices. For most people, the probe punctures and minor burns are the only lasting physical evidence of the encounter, typically healing completely within a week or two.
Bilateral Femoral Neck Fractures and Other Rare Skeletal Injuries
The case reports of fractures caused by TASER-induced muscle contractions deserve a closer look because they illustrate a mechanism many people would not expect. The force of an involuntary contraction driven by external electrical stimulation can exceed the force a person would voluntarily produce, because the normal neurological safeguards that protect your joints and bones from excessive force are bypassed. Your body has built-in mechanisms to limit how hard your muscles pull, including pain feedback loops and inhibitory reflexes, and the electrical override sidesteps these protections.
Documented fractures include bilateral femoral neck fractures, meaning both hip joints broke simultaneously from muscle force alone.22Journal of the American Osteopathic Academy of Orthopedics. Taser-induced Bilateral Femoral Neck Fractures: A Case Report People with prior orthopedic hardware, such as hip replacements or joint resurfacing, may be at heightened risk because the altered mechanics around the implant concentrate force differently.3Arthroplasty Today. TASER-Induced Femoral Neck Fracture Following Hip Resurfacing Arthroplasty in a Law Enforcement Officer Spinal compression fractures, as described earlier, fall into the same category. These injuries are genuinely rare, but they are catastrophic when they occur, often requiring surgery and lengthy rehabilitation. There is no way for the person deploying the device, or the person being tased, to predict whether this will happen, since individual bone density and anatomy vary widely.