When electrical current passes through your body, it can cause effects ranging from a mild tingling sensation to cardiac arrest and death, depending on the voltage, the amount of current, and how long you’re in contact with the source. The body runs on its own tiny electrical signals, and an outside current disrupts those signals in ways that can affect your heart, muscles, nerves, and internal organs simultaneously. About 147 workers die from electrical injuries in the U.S. each year from occupational exposure alone, and thousands more sustain non-fatal injuries at home and on the job.
Why Moisture and Skin Condition Matter
Your skin is the first line of defense against electrical current. A dry, calloused hand can have a resistance of more than 100,000 ohms, which significantly limits how much current enters your body. But that protection drops dramatically when conditions change. A cut, a scrape, or simply wet skin can bypass that resistance almost entirely. When you’re submerged in water, your total body resistance from hand to foot drops to around 300 to 400 ohms. That means the same voltage that gives you a mild shock with dry hands could deliver a lethal amount of current if your skin is wet or broken.
Once current gets past the skin, internal tissues offer very little resistance, roughly 300 ohms, because they’re wet and salty. This is why seemingly low voltages can be dangerous in the right conditions. OSHA considers anything at or above 50 volts hazardous, and even voltages below that aren’t guaranteed safe.
What Happens to Your Muscles
Electricity causes muscles to contract involuntarily. At relatively low current levels, this creates a painful jolt and you can pull away. But above a certain threshold, the current locks your muscles in a sustained contraction called tetany. Your hand clamps down and you physically cannot let go of whatever is shocking you. This is one of the most dangerous aspects of electrical contact, because the longer you hold on, the more current flows through your body and the worse the damage becomes.
This same involuntary contraction can affect your chest muscles and diaphragm, making it impossible to breathe while the current is flowing. If the shock is brief, breathing typically resumes on its own. If it isn’t, suffocation becomes a real risk even before the heart is affected.
How Electrical Current Affects the Heart
The most common cause of death from electrocution is ventricular fibrillation, a chaotic heart rhythm where the heart quivers instead of pumping blood. If the current reaches the heart during a specific vulnerable window in its electrical cycle, it can throw off the coordinated signals that keep the heart beating normally. The damage isn’t necessarily from killing heart tissue directly. Instead, the current disrupts the tiny muscle fibers that form the heart’s conduction system, creating a disorganized electrical pattern that prevents effective pumping.
Ventricular fibrillation is survivable if CPR and defibrillation happen quickly. In one large study of 480 patients who experienced electrical accidents, one patient required 25 minutes of resuscitation after going into ventricular fibrillation at the scene. Heart rhythm problems can also appear less dramatically as irregular heartbeats that develop in the hours after a shock, which is why hospitals monitor heart activity for 12 to 24 hours after a high-voltage exposure.
Burns That Start From the Inside
Electrical burns work differently from thermal burns, and this catches many people off guard. There are two main types. Flash burns happen when an electrical arc superheats the air near you. These are surface burns, similar to a flame burn, ranging from mild redness to thick, leathery damaged skin. The current doesn’t actually pass through your body in a flash burn.
True electrical burns are far more deceptive. When current flows through you, it enters at one point and exits at another, and the worst damage happens at those contact points and along the path between them. The skin at the entry and exit sites may look relatively minor, but deep inside, muscles, blood vessels, and nerves along the current’s path can sustain severe damage. This is sometimes described as an “iceberg injury” because what’s visible on the surface dramatically underestimates what’s happening underneath.
As deep tissues are destroyed, they release proteins into the bloodstream. These proteins can clog the kidneys, potentially leading to kidney failure if not treated quickly. This is one reason why hospital evaluation after a significant shock includes urine testing and blood work even when external injuries look manageable.
Nerve and Brain Effects
The nervous system is especially vulnerable to electrical injury because nerves are essentially biological wires. Permanent nerve damage at the site where current entered the body is extremely common. This can show up as numbness, tingling, chronic pain, or loss of function in the affected limb. Some people develop damage to multiple nerves throughout the body.
The brain is also affected, sometimes in ways that aren’t immediately obvious. Behavioral changes, difficulty with memory, and trouble concentrating are common long-term effects after a significant electrical injury. These neuropsychological symptoms can persist for months or years and are sometimes more disabling than the physical injuries. Loss of consciousness at the time of the shock is a red flag for potential brain involvement.
Delayed Complications
Some consequences of electrical injury don’t appear until weeks or months later. About 6% of people who suffer a significant electrical injury develop cataracts within the first year, with additional cases appearing over the following two years. The exact mechanism isn’t fully understood, but the current’s path near the head and eyes appears to play a role.
Peripheral nerve problems can also worsen or first appear well after the initial injury has healed. Chronic pain syndromes, movement disorders, and psychological effects like anxiety and post-traumatic stress are reported frequently enough that follow-up care after electrical injury typically extends well beyond the initial hospitalization.
What Determines How Severe a Shock Is
Several factors combine to determine whether an electrical shock is a minor nuisance or a life-threatening event:
- Current path: Current traveling from hand to hand crosses the chest and heart. Hand to foot is also dangerous. Current that stays in one finger is far less likely to be fatal.
- Duration of contact: A brief touch delivers far less energy than a sustained grip, especially if tetany prevents you from letting go.
- Voltage and current: Higher voltage drives more current through the body. Household voltage (120V in the U.S.) kills people regularly, particularly when skin resistance is low.
- Type of current: Alternating current (AC), which is what comes from wall outlets, is generally more dangerous than direct current (DC) at the same voltage because it’s more likely to cause tetanic muscle contractions and heart rhythm disturbances.
- Skin condition: Wet, thin, or broken skin lets far more current through than dry, intact skin.
What to Do if Someone Is Being Shocked
If you see someone in contact with an electrical source, do not touch them directly. You will become part of the circuit. Turn off the power source if you can reach it safely. If you can’t, use a dry, non-conducting object like a wooden board, plastic chair, or thick cardboard to push the person or the electrical source apart. Do not use anything wet or metallic.
Once the person is free from the source, check for breathing and signs of circulation. If they’re unresponsive and not breathing, start CPR immediately. Even if someone seems fine after a shock, any exposure involving high voltage, loss of consciousness, visible burns, or passage of current across the chest warrants emergency evaluation. Hospitals will run an electrocardiogram and check blood and urine for signs of heart or muscle damage, and people with abnormal results are typically monitored for at least 12 to 24 hours. People who are fully asymptomatic with a normal exam and normal heart tracing after a low-voltage shock can generally be reassured without further testing.