Concentrated Caffeine Powder, Pre-Workout, and Theophylline Overdose: Tremors, Vomiting, and Arrhythmias¶

Concentrated methylxanthine overdose - most commonly caused by swallowing pure anhydrous caffeine powder, "dry-scooping" multiple scoops of high-stimulant athletic pre-workout supplements, gulping handfuls of 200-milligram caffeine alertness tablets (NoDoz, Vivarin, ProPlus), or taking an acute or chronic overdose of the prescription asthma bronchodilator theophylline (aminophylline) - is a deceptive, life-threatening metabolic and cardiovascular poisoning emergency. While a standard brewed cup of coffee contains 80 to 100 milligrams of caffeine, a single flat household teaspoon of pure 100% anhydrous caffeine powder contains 3,200 to 5,000 milligrams (3.2 to 5 grams) of caffeine - the equivalent of drinking 30 to 50 cups of coffee in one swallow, which hits the threshold for a fatal human dose. If someone who consumed concentrated caffeine, pre-workout, energy shots, or theophylline develops relentless vomiting, violent tremors, a racing or irregular heart rate over 140 beats per minute, chest pain, or seizures, call your local emergency numbers immediately. For related cardiac and electrolyte crises, consult supraventricular tachycardia (SVT) and ventricular arrhythmias, severe hypokalemia and hyperkalemia cardiac arrest, and status epilepticus and prolonged seizures.

Because caffeine and theophylline drive massive beta-adrenergic catecholamine surges inside the heart and force potassium out of the bloodstream into skeletal muscle cells, victims can progress rapidly from jittery vomiting to profound hypokalemia (potassium below 2.5 mmol/L), refractory status epilepticus seizures, hypotension, and sudden ventricular fibrillation cardiac arrest.

Do this now¶

1. Call your local emergency number and Poison Control immediately. Dial 911 in the United States and Canada (and US Poison Control at 1-800-222-1222), 112 across the European Union, 999 in the United Kingdom, 000 in Australia (Australian Poisons Information Centre 13 11 26), or check our directory of emergency numbers. Tell the dispatcher clearly: "Suspected concentrated caffeine / pre-workout / theophylline overdose with severe tachycardia and vomiting."
2. Do NOT induce vomiting (never give syrup of ipecac or stick fingers down the throat). Caffeine and theophylline already stimulate the brainstem vomiting center (chemoreceptor trigger zone) so powerfully that patients vomit relentlessly on their own; forcing gagging triggers a sudden surge in intracranial pressure and catecholamines that can precipitate a seizure or aspirate stomach acid into the lungs right as a seizure strikes.
3. Keep the patient at complete physical rest in a cool, quiet, dimly lit room - and NEVER let them "walk it off," exercise, or take a cold shower. Physical exertion or a shocking cold shower adds another massive spike of endogenous adrenaline (epinephrine) onto a heart muscle already poisoned with cyclic AMP and intracellular calcium, which is the exact trigger that flips supraventricular tachycardia into lethal ventricular fibrillation (VF).
4. If the patient is vomiting or becomes drowsy, confused, or starts seizing, roll them onto their LEFT side (recovery position). Lying on the left side prevents vomit from choking the airway and slightly slows gastric emptying from the stomach through the pyloric sphincter into the small intestine while awaiting paramedics.
5. NEVER give the patient coffee, tea, soda, chocolate, decongestants (pseudoephedrine / phenylephrine), ADHD stimulants, or home beta-blocker pills without emergency physician direction. Adding any stimulant worsens toxicity, and giving an unmonitored oral non-selective beta-blocker at home in a patient with asthma or unknown co-ingestants can trigger severe bronchospasm.
6. Bag up the exact supplement tub, powder packet, or pill bottle (including the measuring scoop) to hand to paramedics. Pre-workout powders and fat-burner capsules frequently combine 300 to 400 mg of anhydrous caffeine per scoop with yohimbine, synephrine (bitter orange), DMAA/DMHA, ephedra alkaloids, or niacin, which require specific toxicology management in the emergency department.

Decision tree: caffeine, pre-workout, and theophylline overdose triage¶

flowchart TD
    A["Ingestion of Caffeine Powder/Pills, Pre-Workout, Energy Drinks, or Theophylline"] --> B{"Calculate approximate dose OR check current symptoms"}
    B -->|"Caffeine > 1,000 mg (1 g) OR any Theophylline overdose OR any pure powder scoop error"| C["CALL 911 / 112 / 999 IMMEDIATELY (Do NOT wait for symptoms)"]
    B -->|"Caffeine 400 to 800 mg: Mild jitteriness, fast heart rate < 120 bpm, mild nausea"| D["Rest quietly, sip water/electrolytes, call Poison Control (1-800-222-1222 in US)"]
    C --> E{"Assess heart rhythm, vomiting, and neurological status"}
    E -->|"Relentless vomiting, coarse tremor, HR > 130 bpm, chest pain, or wide pulse pressure"| F["Place in left-side recovery position, keep completely still, prepare for EMS transport"]
    E -->|"Agitation, muscle twitching, or generalized SEIZURES"| G["Protect head, roll onto left side, do NOT restrain; hospital IV Benzodiazepines + Propofol/Barbiturates"]
    F --> H["Hospital ICU Care: Multidose Activated Charcoal + IV Potassium + IV Esmolol + Hemodialysis"]
    G --> H

Dose-toxicity mathematics: comparing coffee, energy drinks, pre-workout, and pure powder¶

Most accidental caffeine overdoses happen because teenagers, athletes, shift workers, or students do not realize how concentrated modern powders, energy shots, and tablets are compared to brewed beverages.

Key toxicity thresholds by milligram dose (Caffeine)¶

• Up to 400 mg/day in healthy adults (or 2.5 mg/kg/day in children/teens): Safe daily upper limit established by the US FDA and European Food Safety Authority (EFSA).
• 1,000 to 2,000 mg (1 to 2 grams, or > 15 to 20 mg/kg): Moderate-to-severe acute toxicity: Relentless nausea and vomiting, severe restlessness, coarse muscle tremors, flushing, sinus tachycardia or supraventricular tachycardia (130 to 180 bpm), hypokalemia, and metabolic acidosis.
• 3,000 to 5,000+ mg (3 to 5+ grams, or > 50 to 80 mg/kg; serum caffeine > 80 to 100 mcg/mL): Life-threatening / potentially lethal threshold: Refractory generalized tonic-clonic seizures, rhabdomyolysis, severe hypotension (beta-2 vasodilation shock), and fatal ventricular tachycardia or ventricular fibrillation.

How methylxanthines poison the body: the four biochemical mechanisms¶

Caffeine (1,3,7-trimethylxanthine) and theophylline (1,3-dimethylxanthine) are plant alkaloids known as methylxanthines (in fact, the human liver metabolizes about 4 to 10 percent of ingested caffeine directly into theophylline and paraxanthine via the CYP1A2 enzyme). In an overdose, four distinct biochemical mechanisms attack the brain, heart, blood vessels, and electrolytes simultaneously:

1. Competitive blockade of brain Adenosine A1 and A2A receptors (Why seizures won't stop)¶

Under normal conditions, adenosine is the brain's built-in "circuit breaker." When brain neurons fire too rapidly, adenosine builds up and binds to inhibitory Adenosine A1 receptors, slowing down neuronal firing, dilating cerebral blood vessels, and preventing seizures.

Caffeine and theophylline have a molecular shape nearly identical to adenosine. In an overdose, they pack into every Adenosine A1 and A2A receptor across the cerebral cortex and brainstem without activating them - cutting the brake lines on the human brain while constricting cerebral blood vessels by 25 to 30 percent. Deprived of adenosine braking, the brain erupts in generalized status epilepticus seizures that do not respond to standard sodium-channel anticonvulsants like phenytoin or fosphenytoin.

2. Phosphodiesterase (PDE) inhibition and massive Catecholamine flood ("Beta-Adrenergic Storm")¶

At toxic blood concentrations, caffeine and theophylline inhibit the enzyme intracellular phosphodiesterase (PDE3 and PDE4) - the enzyme responsible for breaking down cyclic AMP (cAMP) inside heart and smooth muscle cells - while simultaneously triggering the adrenal glands to dump massive quantities of epinephrine and norepinephrine into the bloodstream. Intracellular cAMP skyrockets, creating a ferocious Beta-1 and Beta-2 adrenergic storm:

• Beta-1 cardiac hyperstimulation: The sinoatrial node, atrioventricular node, and ventricular myocardium are whipped into extreme tachycardia (140 to 220 beats per minute), increasing myocardial oxygen demand while shortening diastolic coronary filling time, causing subendocardial myocardial ischemia and infarction even in teenagers with normal coronary arteries.
• Paradoxical Beta-2 peripheral vasodilation and shock: While people think of caffeine as raising blood pressure, in a severe overdose, intense Beta-2 receptor stimulation on peripheral arterioles causes massive systemic vasodilation. The diastolic (bottom) blood pressure number plunges to 20 to 40 mmHg (creating a wide pulse pressure, e.g., 130/30 mmHg), followed by profound vasodilatory and cardiogenic hypotension (shock).

3. Severe intracellular Potassium shift (Hypokalemia < 2.5 mmol/L) and Lactic Acidosis¶

The massive surge of beta-2 adrenergic stimulation and cyclic AMP hyper-activates the Sodium-Potassium-ATPase (Na+/K+-ATPase) pump on the surface of every skeletal muscle cell in the body.

• What happens to blood potassium: Within 1 to 3 hours of a caffeine or theophylline overdose, the overdriven Na+/K+-ATPase pumps vacuum potassium out of the bloodstream and lock it inside skeletal muscle cells. Serum potassium plunges from a normal 4.0 mmol/L down to 2.0 to 2.8 mmol/L (severe acute redistributive hypokalemia), accompanied by high blood sugar (hyperglycemia), low phosphate (hypophosphatemia), low magnesium (hypomagnesemia), and high lactic acid (metabolic acidosis).
• Why hypokalemia triggers sudden death: A heart muscle being whipped at 180 beats per minute by adrenaline while bathed in critically low potassium (< 2.5 mmol/L) develops extreme electrical instability (QT prolongation, U-waves, premature ventricular contractions), culminating in polymorphic ventricular tachycardia (Torsades de Pointes) and ventricular fibrillation.

4. Direct Sarcoplasmic Reticulum Calcium Release (Ryanodine Receptor Activation)¶

At very high concentrations, methylxanthines directly open ryanodine calcium channels (RyR) on the sarcoplasmic reticulum inside skeletal and cardiac muscle fibers, flooding the cytoplasm with free calcium ions (Ca2+). This causes relentless coarse muscle tremors, muscle rigidity, hyperthermia, and massive rhabdomyolysis (myoglobinuria and acute kidney failure).

Acute vs. Chronic Theophylline Toxicity: a critical distinction for asthma and COPD patients¶

While caffeine overdoses are usually single acute ingestions in young adults, theophylline toxicity affects patients with asthma or Chronic Obstructive Pulmonary Disease (COPD) and has a much narrower therapeutic window (normal therapeutic level: 5 to 15 mcg/mL; toxic: > 20 mcg/mL). Clinicians divide theophylline poisoning into two distinct syndromes with very different rules:

Why "Dry-Scooping" Pre-Workout Powder is Doubly Dangerous¶

A viral gym trend called "dry-scooping" - pouring a dry scoop of concentrated pre-workout powder directly into the mouth and trying to swallow it without mixing it in 250 to 350 milliliters (8 to 12 ounces) of water - causes two immediate medical emergencies in addition to caffeine overdose:

1. Acute Aspiration Pneumonitis and Laryngospasm ("The Cinnamon Challenge Effect"): Dry pre-workout powder is an ultra-fine, hydrophobic/hygroscopic dust mixed with citric acid, malic acid, beta-alanine, and 300 to 400 mg of caffeine. When a person inhales even slightly while a cloud of dry acidic powder is in their mouth, the powder sucks all moisture off the vocal cords and shoots straight down the trachea into the bronchioles, triggering violent laryngospasm, severe bronchospasm, and chemical aspiration pneumonia.
2. Instantaneous Buccal/Mucosal Absorption and Coronary Artery Spasm: Instead of sipping a diluted drink over 20 to 30 minutes before a workout, swallowing an undiluted 350-mg bolus of caffeine combined with synephrine (bitter orange extract), yohimbine, or hordenine right before lifting heavy weights causes an explosive spike in coronary artery alpha-adrenergic tone, triggering acute coronary vasospasm, ST-elevation myocardial infarction (heart attack), or aortic dissection in otherwise healthy 18-to-30-year-olds.

Dangerous hidden co-ingestants in pre-workout and "fat-burner" capsules¶

When reporting a pre-workout or weight-loss supplement overdose to Poison Control or emergency room clinicians, check the supplement's "Proprietary Blend" label for five synergistic stimulants that dramatically amplify caffeine's lethality:

• Synephrine (Citrus aurantium / Bitter Orange extract) and Octopamine: Structural cousins of ephedrine and phenylephrine that stimulate Alpha-1 and Beta-3 adrenergic receptors. While caffeine dilates peripheral beta-2 vessels and speeds up the heart, synephrine clamps down on coronary and cerebral arteries, causing hypertensive crisis, ischemic stroke, and acute coronary thrombosis.
• Yohimbine (Pausinystalia johimbe bark extract / Rauwolscine): A potent central Alpha-2 adrenergic receptor antagonist. Normally, central alpha-2 receptors act as the brainstem's thermostat to shut off excess norepinephrine release (the exact receptor that clonidine activates to calm the nervous system). Blocking alpha-2 receptors with yohimbine while taking caffeine causes an unstoppable flood of central norepinephrine, severe panic, skyrocketing blood pressure, manic agitation, and refractory tachycardia.
• DMAA (1,3-dimethylamylamine), DMHA (octodrine), and Ephedra Alkaloids: Synthetic or botanical amphetamine-like sympathomimetics illegally adulterated into hardcore "underground" pre-workouts that cause intracerebral hemorrhage, acute liver failure, and exertional heat stroke.
• Concentrated Green Tea Extract (EGCG) and Guarana / Yerba Mate / Kola Nut: Botanical sources of caffeine that are often listed separately on ingredient labels without disclosing that they add an extra 150 to 250 milligrams of hidden caffeine per serving on top of the listed "caffeine anhydrous" amount.
• Beta-Alanine and Concentrated Niacin (Vitamin B3): Cause intense, harmless-but-terrifying paresthesias (burning, prickling, pins-and-needles itching across the face, ears, neck, and hands) and bright red skin flushing (niacin flush) within 15 minutes of ingestion. While beta-alanine tingling and niacin flushing are not life-threatening on their own, when combined with a 600-mg caffeine overdose they frequently trigger hyperventilation and panic that worsen cardiac arrhythmias.

Why mixing energy drinks or caffeine pills with alcohol ("Wide-Awake Drunk") or ADHD medications is a medical trap¶

Two everyday drug combinations turn moderate caffeine consumption into an emergency department crisis:

1. Caffeine + Alcohol ("Wide-Awake Drunk" Syndrome): When a person drinks high-caffeine energy drinks mixed with vodka or spirits, caffeine blocks the Adenosine A1 sleepiness signals in the brain that normally tell an intoxicated person they are drunk and need to stop drinking. However, caffeine does NOT reduce blood alcohol concentration, does NOT improve coordination, and does NOT prevent respiratory depression. The person feels artificially alert and continues chugging alcohol past the threshold for lethal acute alcohol poisoning (BAC > 0.30%), while the combination of alcohol dehydration, electrolyte loss, and high-dose caffeine triggers atrial fibrillation ("Holiday Heart Syndrome") and supraventricular tachycardia.
2. Caffeine + Prescription ADHD Stimulants (Amphetamine/Dextroamphetamine [Adderall], Lisdexamfetamine [Vyvanse], Methylphenidate [Ritalin/Concerta]) or Asthma Inhalers (Albuterol): Amphetamines and methylphenidate flood the synapses with dopamine and norepinephrine, while caffeine blocks adenosine and prevents intracellular breakdown of cyclic AMP. Taking pre-workout or energy drinks on top of daily ADHD medication produces additive sympathomimetic toxidrome (heart rate > 160 bpm, chest pain, hyperthermia, dilated pupils, tremor, and rhabdomyolysis).

How emergency departments treat severe caffeine and theophylline overdose¶

When a patient arrives at the hospital with severe methylxanthine poisoning, emergency physicians and medical toxicologists execute a specialized 5-part resuscitation protocol that differs markedly from standard cardiac care:

1. Gastrointestinal Decontamination & "Gut Dialysis" (Multidose Activated Charcoal):
2. If the patient ingested extended-release theophylline tablets (Theo-24, Uniphyl) or a massive load of caffeine pills, tablets often clump together into a sticky pharmacobezoar in the stomach that slowly releases poison for 24 hours.
3. After controlling relentless vomiting with high-dose intravenous ondansetron (Zofran, 8 mg IV) or metoclopramide, clinicians administer Multidose Activated Charcoal (MDAC: 25 to 50 grams every 2 to 4 hours) (or Whole-Bowel Irrigation with polyethylene glycol for massive sustained-release theophylline bezoars). Because caffeine and theophylline continuously diffuse out of the intestinal capillary blood back into the gut lumen, repeated doses of activated charcoal in the gut act like "enterocapillary gut dialysis," cutting the drug's elimination half-life in half even after it has already been absorbed into the bloodstream.
4. Aggressive Intravenous Benzodiazepines + Phenobarbital/Propofol for Seizures:
5. First-line treatment to stop or prevent methylxanthine seizures is high-dose intravenous lorazepam (Ativan), diazepam (Valium), or midazolam (Versed), escalated rapidly to intravenous phenobarbital or propofol general anesthesia with endotracheal intubation. Phenytoin (Dilantin) is strictly contraindicated, as animal and human data show phenytoin fails to stop methylxanthine seizures and worsens cardiac arrhythmias.
6. Paradoxical Treatment of Low Blood Pressure and Tachycardia with an Ultra-Short-Acting Beta-Blocker (IV Esmolol) or Alpha-1 Agonist (Phenylephrine):
7. When a patient with caffeine or theophylline overdose has a heart rate of 190 bpm and a crashing blood pressure of 70/30 mmHg, giving standard beta-agonists like epinephrine, dopamine, or isoproterenol will worsen beta-2 vasodilation and kill the patient.
8. Instead, after infusing 0.9% normal saline boluses, toxicologists administer a pure alpha-1 vasoconstrictor (phenylephrine or norepinephrine) to tighten the dilated blood vessels, OR give a cautious titrated infusion of an ultra-short-acting beta-blocker (esmolol or propranolol in non-asthmatics). Counterintuitively, blocking the overstimulated beta-2 receptors with esmolol stops peripheral beta-2 vasodilation and slows the heart enough for the ventricles to fill during diastole, causing blood pressure to RISE back to normal while stopping ventricular arrhythmias.
9. Cautious Potassium Replacement (Avoiding Rebound Hyperkalemia):
10. Clinicians replace severe hypokalemia (K+ < 2.5 to 3.0 mmol/L) with intravenous potassium chloride to protect against ventricular fibrillation, but monitor potassium closely every 1 to 2 hours. Because the patient's total body potassium was never actually lost in urine - it was merely hidden inside muscle cells by beta-2 stimulation - once the caffeine clears or esmolol is given, all that potassium floods back out of the muscles into the blood, which can cause dangerous rebound hyperkalemia if too much IV potassium was infused.
11. Emergency Extracorporeal Removal (Intermittent Hemodialysis):
12. Caffeine and theophylline are small, water-soluble molecules with a small volume of distribution (0.5 L/kg), meaning intermittent hemodialysis removes them from the bloodstream with extraordinary speed. Under EXTRIP (Extracorporeal Treatments in Poisoning) Workgroup guidelines, emergency hemodialysis is performed immediately for any patient with methylxanthine seizures, life-threatening arrhythmias, shock, rising levels despite charcoal, or serum theophylline > 100 mcg/mL (acute) or > 60 mcg/mL (chronic).

Regional emergency numbers and agency protocols¶

• United States and Canada: Call 911 for severe tachycardia, chest pain, relentless vomiting, or seizures, or call US Poison Control at 1-800-222-1222 (Canada: 1-844-POISON-X / 1-844-764-7669). The US Food and Drug Administration (FDA) issued federal warning letters and outlawed consumer bulk sales of pure powdered anhydrous caffeine after documenting fatal teaspoon-measurement overdoses, and the American Association of Poison Control Centers (AAPCC) and EXTRIP Workgroup guide hospital esmolol, MDAC, and hemodialysis protocols.
• United Kingdom: Call 999 for an emergency ambulance, or 111 for non-emergent advice. UK National Poisons Information Service (NPIS / TOXBASE) protocols direct immediate cardiac monitoring, potassium correction, intravenous benzodiazepines for CNS excitation, and multidose activated charcoal/hemodialysis for severe theophylline or caffeine toxicity.
• European Union: Call 112. The European Food Safety Authority (EFSA) Scientific Opinion on the Safety of Caffeine sets acute single-dose safety limits at 200 mg (3 mg/kg), while European Resuscitation Council (ERC) toxicology guidelines govern management of methylxanthine-induced tachyarrhythmias and status epilepticus.
• Australia and New Zealand: Call 000 in Australia (Poisons Information Centre 13 11 26) or 111 in New Zealand (National Poisons Centre 0800 764 766). The Therapeutic Goods Administration (TGA) and Food Standards Australia New Zealand (FSANZ) ban the retail sale of pure and highly concentrated caffeine powders (containing >= 5% caffeine in solid foods or >= 1% in liquids).
• India and Asia-Pacific: Call 112 in India, 995 in Singapore, 119 in Japan and South Korea, or 999 in Malaysia and Hong Kong. See our complete list of international emergency numbers.

Frequently asked questions¶

How can a single teaspoon of caffeine powder kill a healthy person when people drink coffee every day?¶

A normal 8-ounce cup of brewed coffee contains roughly 80 to 100 milligrams of caffeine diluted in a large mug of water that takes 15 to 30 minutes to drink. Pure 100 percent anhydrous caffeine powder is a concentrated pharmaceutical chemical where a single level household teaspoon (about 5 milliliters by volume) weighs 3.2 to 5.0 grams - delivering 3,200 to 5,000 milligrams of pure caffeine in a single swallow. That is equivalent to chugging 35 to 50 cups of coffee simultaneously, overwhelming the liver's enzymes and triggering fatal ventricular arrhythmias and status epilepticus seizures within 30 to 90 minutes.

Why does a severe caffeine or pre-workout overdose make blood pressure DROP instead of just going up?¶

In mild or moderate doses, caffeine slightly raises blood pressure by blocking adenosine receptors and releasing adrenaline. However, in a massive overdose, extremely high levels of caffeine and adrenaline overstimulate Beta-2 adrenergic receptors located in the smooth muscle walls of arterioles throughout the skeletal muscles. Beta-2 stimulation causes those blood vessels to dilate wide open, causing the bottom (diastolic) blood pressure number to plummet and plunging the patient into life-threatening vasodilatory shock while the heart races at 180 to 200 beats per minute.

Can drinking lots of water or going for a run "flush out" a pre-workout or caffeine overdose faster?¶

No - and trying to exercise or "sweat out" a caffeine overdose can be fatal. Less than 1 to 3 percent of caffeine is excreted unchanged in urine or sweat; the other 97 percent must be slowly broken down by the CYP1A2 enzyme in your liver, which gets completely saturated and backed up during an overdose. Running, lifting weights, or taking an ice-cold shower releases a surge of your body's own adrenaline on top of the caffeine, which can push a fast heart rate directly into fatal ventricular fibrillation cardiac arrest. The person must lie or sit quietly at complete physical rest.

Why does adenosine (the standard hospital drug for SVT) fail to work when someone has SVT from a caffeine or energy drink overdose?¶

In a normal patient with Supraventricular Tachycardia (SVT), paramedics or emergency doctors inject a rapid 6-mg or 12-mg intravenous push of adenosine, which binds to Adenosine A1 receptors in the heart's AV node to briefly pause the electrical short-circuit and reset a normal rhythm. Because caffeine and theophylline are direct competitive blockers sitting inside those exact same Adenosine A1 receptors, standard doses of IV adenosine bounce right off and fail to slow the heart - or can paradoxically trigger bronchospasm in theophylline patients. Hospital doctors instead use intravenous benzodiazepines, diltiazem/esmolol, or synchronized electrical cardioversion.

Why do antibiotics like ciprofloxacin or erythromycin cause sudden theophylline poisoning in asthma patients who didn't take extra pills?¶

The prescription bronchodilator theophylline is cleared from the human body almost entirely by one specific liver enzyme called Cytochrome P450 1A2 (CYP1A2). Common antibiotics - especially fluoroquinolones like ciprofloxacin and macrolides like erythromycin or clarithromycin - as well as fluvoxamine and cimetidine powerfully inhibit the CYP1A2 enzyme. Within 2 to 5 days of starting ciprofloxacin, the patient's usual daily theophylline pills stop being broken down and accumulate to toxic levels in the blood, causing chronic theophylline poisoning and sudden seizures without any extra pills ever being swallowed.

Sources and official guidance¶

• EXTRIP (Extracorporeal Treatments in Poisoning) Workgroup: Systematic Review and Recommendations for Extracorporeal Treatment in Theophylline and Methylxanthine Poisoning (Ghannoum M et al., Clinical Toxicology: hemodialysis thresholds for acute vs. chronic toxicity, multidose activated charcoal gut dialysis, and mortality of methylxanthine seizures).
• US Food and Drug Administration (FDA) & Center for Food Safety and Applied Nutrition (CFSAN, United States): FDA Guidance for Industry: Highly Concentrated Caffeine in Dietary Supplements (Lethal dose thresholds of bulk anhydrous caffeine powder and teaspoon measurement hazards).
• American Heart Association (AHA, United States): 2023 Focused Update and Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: Management of Critical Poisoning (Sympathomimetics, Methylxanthines, Esmolol for Beta-2 Vasodilatory Shock, and Refractory Tachyarrhythmias).
• European Food Safety Authority (EFSA, European Union): Scientific Opinion on the Safety of Caffeine (EFSA Panel on Dietetic Products, Nutrition and Allergies: single-dose and daily cardiovascular/CNS thresholds and co-ingestion with synephrine/energy drink ingredients).
• National Poisons Information Service (NPIS / TOXBASE, United Kingdom) & Therapeutic Goods Administration (TGA, Australia): Clinical Management of Acute Caffeine and Theophylline Overdose (Hypokalemia Shift, Benzodiazepine/Barbiturate Anticonvulsant Hierarchy, and Ondansetron + MDAC).

Related guides¶

• Supraventricular tachycardia (SVT), vagal maneuvers, and ventricular arrhythmias
• Severe hypokalemia and hyperkalemia, periodic paralysis, and peaked T-wave cardiac arrest
• Status epilepticus, prolonged seizures, and rescue medications
• Asthma attack emergency response
• Poisoning first aid and toxic exposure