Multiple classes of drugs, from prescription medications to street stimulants, can trigger cardiac arrest through well-documented mechanisms that disrupt the heart’s electrical signaling or damage the heart muscle directly. The connection is not limited to illicit substances: common antibiotics, antipsychotics, antidepressants, cancer treatments, and even some over-the-counter products have been linked to sudden cardiac death in published research. The pathways vary, but many converge on the same handful of vulnerabilities in the heart’s electrical system, and certain people carry higher risk than others based on their genetics, sex, or metabolic state.
How Drugs Disrupt the Heart’s Electrical System
Your heart relies on a precisely timed flow of charged particles (ions) through specialized channels in cardiac cells. The most common drug-related route to cardiac arrest involves interference with one particular potassium channel called hERG, which plays a central role in resetting the electrical charge of heart cells between beats. When a drug blocks this channel, the heart takes longer to reset, a delay that shows up on an electrocardiogram as a prolonged QT interval. That delay creates a window where the heart is vulnerable to a dangerous rhythm called torsades de pointes, a type of ventricular arrhythmia that can spiral into ventricular fibrillation and cardiac arrest.1PubMed. QT prolongation through hERG K(+) channel blockade: current knowledge and strategies for the early prediction during drug development This mechanism is so pervasive that regulators now require virtually all new drugs seeking approval to be tested for hERG channel effects before reaching the market.2PubMed. Drug-induced hERG block and long QT syndrome
Not all drugs block hERG in the same way. Some bind directly to the channel and shut it down immediately. Others, like the anti-parasitic drug pentamidine, do not block the channel acutely at all. Instead, pentamidine interferes with the channel’s ability to reach the cell surface, gradually reducing the number of working channels over hours of exposure. The end result is the same: fewer functional potassium channels, delayed electrical reset, and risk of fatal arrhythmia.3The Journal of Pharmacology and Experimental Therapeutics. Pentamidine-Induced Long QT Syndrome and Block of hERG Trafficking
Potassium channels are not the only target. Some drugs block sodium channels in the heart, which slows the initial electrical impulse that travels through heart muscle. This shows up as a widened QRS complex on an electrocardiogram and can lead to conduction failure, where the electrical signal simply stops propagating through the ventricles.4PubMed Central. An overview of drug-induced sodium channel blockade and changes in cardiac conduction: Implications for drug safety Sodium channel blockade has been tied to increased mortality in patients with underlying cardiovascular disease.5PubMed Central. On the relationship between block of the cardiac Na⁺ channel and drug-induced prolongation of the QRS complex
Illicit Stimulants and Cardiac Arrest
Cocaine and methamphetamine are probably the substances most commonly associated with drug-related cardiac arrest in public awareness, and the science supports that reputation through several overlapping mechanisms. These drugs flood the body with catecholamines, the “fight-or-flight” chemicals that jack up heart rate and blood pressure. But they also act directly on cardiac ion channels and calcium-handling proteins, changing both the structure and the electrical behavior of heart muscle over time.6PubMed Central. Stimulant Drugs of Abuse and Cardiac Arrhythmias The result is a heart that is simultaneously overworked, structurally altered, and electrically unstable.
Cocaine’s electrophysiology has been studied in detail. In animal cardiac tissue, cocaine does not simply stop the heart’s pacemaker. Instead, it drops the resting electrical charge of muscle fibers and weakens each electrical impulse, eventually blocking the signal from spreading through the heart. The pacemaker keeps firing, but the muscle stops responding, a mechanism that can explain sudden death in an otherwise young, apparently healthy user.7PubMed. Electrophysiological mechanisms of cocaine-induced cardiac arrest. A possible cause of sudden cardiac death
Methamphetamine adds another pathway: coronary vasospasm. It can cause the arteries that feed the heart to clamp down abruptly, starving a patch of heart muscle of blood. It can also destabilize fatty plaques in those arteries. Either event triggers ischemia and potentially lethal arrhythmias.8PubMed Central. Methamphetamine-Induced Coronary Vasospasm and Recurrent Cardiac Arrest: A Quick Glance May Not Be Good Enough Synthetic cathinones (“bath salts”) and amphetamine-type stimulants share similar sympathomimetic effects, causing arrhythmia, ischemia, and direct myocardial injury.9PubMed. Acute cardiovascular complications of sympathomimetic recreational drug use
When Alcohol Meets Cocaine
Polysubstance use introduces dangers that neither drug produces alone. The combination of cocaine and alcohol is a well-studied example. When both are present in the body, the liver produces a unique metabolite called cocaethylene that does not form from either substance by itself. Cocaethylene blocks cardiac ion channels and is associated with an 18- to 25-fold increase in the risk of sudden death compared to cocaine use without cocaethylene.10PubMed Central. Cardiovascular Risks of Simultaneous Use of Alcohol and Cocaine—A Systematic Review
In emergency department patients with acute drug overdose, those who tested positive for cocaethylene were far more likely to go into cardiac arrest requiring CPR than patients who had used cocaine alone. Even after adjusting for age, sex, race, and pre-existing heart disease, cocaethylene remained strongly associated with cardiac arrest.11PubMed Central. Cocaethylene cardiotoxicity in emergency department patients with acute drug overdose This is a practical point: someone using cocaine may dramatically raise their risk simply by having a drink, and most users are not aware of it.
Opioids and a Different Route to Arrest
Opioid-associated cardiac arrest looks different from stimulant-related arrest. Rather than triggering a chaotic electrical storm in the ventricles, opioids typically suppress breathing to the point where the body becomes severely oxygen-deprived. The resulting hypoxia steadily reduces cardiac output, leading to dangerously slow heart rates and eventually pulseless electrical activity or asystole, where the heart effectively stops pumping. This pathway is distinct from the sudden ventricular fibrillation seen with stimulants or drugs that prolong the QT interval.12ClinicalTrials.gov. Naloxone for Opioid Associated Out of Hospital Cardiac Arrest Because the mechanism is fundamentally respiratory in origin, the treatment approach is different too: naloxone, a competitive opioid-receptor blocker, can reverse the respiratory and circulatory depression if given early enough.
Prescription Medications That Raise the Risk
The drug classes linked to cardiac arrest extend well beyond illegal substances. The research literature highlights several categories of everyday prescription medications.
Antipsychotics and Antidepressants
Psychotropic medications are among the most frequently studied drugs in the sudden cardiac death literature.13PubMed Central. Drug-induced Sudden Death: A Scoping Review A number of antipsychotics and antidepressants are known to increase the risk of ventricular arrhythmias and sudden cardiac death. Some prolong the QT interval, while others produce a pattern resembling Brugada syndrome, a different electrical abnormality that also predisposes to fatal arrhythmias.14PubMed Central. Mechanisms Underlying the Actions of Antidepressant and Antipsychotic Drugs That Cause Sudden Cardiac Arrest
A large study published in the New England Journal of Medicine found that current users of both older (“typical”) and newer (“atypical”) antipsychotics had roughly double the rate of sudden cardiac death compared to nonusers. The risk increased with dose for both drug classes.15PubMed Central. Atypical antipsychotic drugs and the risk of sudden cardiac death This finding matters because atypical antipsychotics were initially hoped to carry less cardiac risk than the older drugs. The data suggest otherwise.
Antibiotics
Certain macrolide and fluoroquinolone antibiotics also prolong the QT interval and have been associated with increased risk of ventricular arrhythmia and cardiac arrest. An Italian observational study using three different analytical designs consistently found elevated risk with recent use of both macrolides and fluoroquinolones.16PubMed. Effect of macrolide and fluoroquinolone antibacterials on the risk of ventricular arrhythmia and cardiac arrest: an observational study in Italy using case-control, case-crossover and case-time-control designs A Taiwanese nationwide study added more specificity, finding that azithromycin and moxifloxacin carried meaningfully elevated risks of ventricular arrhythmia and cardiovascular death compared to amoxicillin-clavulanate, while some other agents in the same antibiotic families showed little or no excess risk.17Clinical Infectious Diseases. Risks of Cardiac Arrhythmia and Mortality Among Patients Using New-Generation Macrolides, Fluoroquinolones, and β-Lactam/β-Lactamase Inhibitors: A Taiwanese Nationwide Study The practical implication: not all antibiotics in a given class carry the same cardiac risk, and alternative choices exist for patients who are vulnerable.
Cancer Treatments
Chemotherapy and other cancer treatments can damage the heart through mechanisms that go beyond ion channel effects. Anthracyclines, a widely used class of chemotherapy drugs, cause dose-dependent injury to heart muscle cells through oxidative stress, mitochondrial damage, and disruption of iron handling. This can lead to progressive weakening of the ventricles, accompanied by arrhythmias and, in some cases, sudden cardiac death.18PubMed Central. Chemotherapy-Induced Cardiotoxicity: Mechanisms, Detection and Emerging Therapies in Cardio-Oncology Newer cancer therapies have broadened the problem: targeted agents, immune checkpoint inhibitors, and even CAR T-cell therapy each introduce their own forms of cardiac toxicity, from hypertension and ischemia to immune-mediated inflammation of the heart.19PubMed Central. Cancer therapy-induced cardiotoxicity: mechanisms and mitigations The growing field of cardio-oncology exists specifically because the cardiac risks of cancer treatment have become impossible to ignore.
Over-the-Counter Products and Supplements
You do not need a prescription or a drug dealer to encounter cardiac risk. Ephedra-containing supplements, widely marketed for weight loss and athletic performance before regulatory crackdowns, were linked to stroke, heart attack, and sudden death.20PubMed. Cardiovascular effects of ephedra alkaloids: a comprehensive review Even after ephedra was restricted, weight-loss supplements have continued to cause problems. A case report documented a healthy woman who went into ventricular fibrillation and cardiac arrest after using commercially available weight-loss preparations, with the ingredients suspected of having proarrhythmic effects.21PubMed Central. The risky side of weight-loss dietary supplements: disrupting arrhythmias causing sudden cardiac arrest
Even mundane products can pose danger in the wrong circumstances. Oxymetazoline, the active ingredient in many nasal decongestant sprays, has been reported to cause acute coronary syndrome and cardiac arrest when taken in overdose, including in young people without pre-existing heart disease.22PubMed Central. Acute myocardial infarction and cardiac arrest induced by oxymetazoline nasal spray overdose: a case report This does not mean nasal spray is dangerous at normal doses, but it illustrates that sympathomimetic chemicals can reach the heart even from unexpected delivery routes.
Why Some People Are More Vulnerable
The same drug at the same dose can be harmless for one person and deadly for another. Several factors shift the risk threshold.
Sex is one of the strongest. Women face a higher risk of drug-induced torsades de pointes than men. Research using human stem-cell-derived heart cells found that female-derived cells were more sensitive to drugs that block the hERG channel, showing steeper electrical delays and more frequent arrhythmias than male-derived cells. Differences in the expression of the KCNE1 gene and reduced “repolarization reserve” in female cells may partially explain the gap.23PubMed. Sex-Related Differences in Drug-Induced QT Prolongation and Torsades de Pointes: A New Model System with Human iPSC-CMs Clinical data back this up: a pooled analysis of over 3,000 patients receiving the antiarrhythmic drug d,l-sotalol found that women had roughly three times the odds of developing torsades de pointes compared to men, even after adjusting for dose and other risk factors. The difference was not explained by age or by how much the drug slowed heart rate in women versus men.24PubMed. Sex difference in risk of torsade de pointes with d,l-sotalol
Genetics also plays a role, though translating that into clinical practice remains a work in progress. In a large case-control study of over 6,000 patients treated with QT-prolonging medications, a specific variant in the KCNE1 gene (known as D85N) was significantly associated with drug-induced long QT syndrome, with carriers having roughly double the odds of developing the condition.25PubMed Central. Genetic risk factors for drug-induced long QT syndrome: findings from a large real-world case-control study Other candidate variants in cardiac ion channel genes have also been proposed, but many remain understudied due to their rarity.
Electrolyte imbalances are an underappreciated modifier. Low potassium and low magnesium both amplify the arrhythmic risk of drugs that block hERG channels, essentially lowering the threshold at which a drug tips the heart into a dangerous rhythm.26PubMed Central. Metabolic and electrolyte abnormalities as risk factors in drug-induced long QT syndrome Other modifying factors include fever, acidic blood pH, slow heart rate (bradycardia), and kidney impairment that raises drug levels in the bloodstream. A review of drug-induced long QT cases noted that patients who developed the arrhythmia almost always had at least one additional risk factor beyond the drug itself.27PubMed Central. Causes and management of drug-induced long QT syndrome In other words, the drug rarely acts alone: it is usually the drug plus some other vulnerability that pushes a person over the edge.
Drugs That Have Been Pulled from the Market
The risk of drug-induced cardiac arrest is not just a theoretical concern for pharmacologists. It has driven real regulatory action. Several drugs have been restricted or withdrawn from the market specifically because of an unacceptable rate of fatal arrhythmias linked to QT prolongation.28PubMed Central. Drug-induced QT interval prolongation: mechanisms and clinical management The antihistamine terfenadine, the gastrointestinal drug cisapride, and the antibiotic grepafloxacin are among the better-known examples. Each was effective for its intended purpose but was ultimately judged too dangerous to the heart to remain freely available. These withdrawals reshaped how the pharmaceutical industry develops drugs. Today, hERG channel testing is a standard gatekeeping step in early drug development: a compound that strongly blocks hERG is flagged for extra scrutiny or abandoned before it ever reaches human trials.
Emergency Treatment When a Drug Triggers Arrest
When cardiac arrest is suspected to be drug-related, treatment can sometimes be tailored to the specific substance involved. Sodium bicarbonate is a standard intervention for arrests caused by drugs that block sodium channels, such as tricyclic antidepressants, because it helps restore sodium channel function. For lipophilic drugs (those that dissolve easily in fat), intravenous lipid emulsion has emerged as a rescue therapy. The idea is that the lipid creates a “sink” in the bloodstream that pulls the drug out of cardiac tissue, restoring electrical function. A case report described a patient in prolonged cardiac arrest after overdosing on bupropion and lamotrigine who regained a sustained pulse within a minute of receiving an intravenous bolus of lipid emulsion, after standard resuscitation had failed.29PubMed. Use of lipid emulsion in the resuscitation of a patient with prolonged cardiovascular collapse after overdose of bupropion and lamotrigine Lipid emulsion does not work for every substance or every route of administration: a case involving chloroquine overdose found that intraosseous lipid emulsion failed to improve circulation, likely because the lipid stayed in the bone marrow compartment rather than reaching the bloodstream.30PubMed. Cardiac arrest following chloroquine overdose treated with bicarbonate and lipid emulsion These cases highlight why knowing which drug a patient took, and through what route, can change the outcome in an emergency.
Herbal Products and Plant-Derived Cardiac Toxins
The boundary between “drug” and “natural product” is thinner than many people assume. Numerous plants contain compounds that act on the same cardiac ion channels targeted by pharmaceutical drugs. Digitalis from foxglove is the famous example, but cardiac glycosides appear in oleander, lily of the valley, and several other species used in traditional medicine. With many plant-derived preparations, the margin between a therapeutic dose and a toxic dose can be extremely narrow, making accidental cardiac toxicity a genuine risk for people who self-medicate with herbal products or teas.31ScienceDirect. Heart and Toxins – Chapter 5 – Plant Toxins and the Heart Supplements marketed as “natural” energy boosters or weight-loss aids often contain plant-derived stimulants whose cardiac effects are poorly studied and whose doses are inconsistently standardized. The assumption that “natural” equates to “safe for the heart” has no basis in pharmacology.