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Paraquat, Diquat, and Concentrated Herbicide Exposure: Immediate Decontamination and Care

Emergency numbers differ by country. This page uses 911, the number for the United States and Canada. Many other countries use 112, 999, or another number. Find the number for your country.

Commercial and agricultural herbicides (weed killers) range from relatively low-toxicity diluted homeowner garden sprays to some of the most rapidly corrosive and lethal industrial poisons on Earth. Foremost among these is Paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride, sold under agricultural brand names such as Gramoxone, Parazone, Firestorm, and Helmquat) and its chemical relative Diquat (sold in commercial and aquatic weed killers such as Reward, Reglone, and certain Tribune or landscape formulations), alongside concentrated agricultural Glyphosate-Surfactant solutions (such as Roundup Pro / 41% Concentrate) and Chlorophenoxy herbicides (2,4-D and Dicamba). Swallowing even one single mouthful (10 to 15 milliliters, or 1 tablespoon) of concentrated 20% liquid paraquat, or absorbing paraquat through abraded, cut, or ulcerated skin during backpack spraying without protective gear, causes catastrophic caustic burns of the throat and esophagus, acute renal tubular necrosis, and relentless free-radical pulmonary fibrosis that suffocates the lungs over days to weeks.

If you or someone nearby has swallowed ANY herbicide, splashed concentrated weed killer into the eyes or onto the skin, or accidentally drunk paraquat or glyphosate that was poured into a beverage bottle, call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom) via our emergency numbers directory right away, and review poisoning first aid, chemical burns, and organophosphate pesticide poisoning. Because every minute of delay allows paraquat to actively pump itself into lung cells, immediate skin washing, swallowing an oral adsorbent within the first 60 minutes, and strictly withholding routine supplemental oxygen unless severe hypoxemia occurs are critical life-or-death actions.

Do this now

  1. Call 911 / 112 / 999 immediately and alert the ambulance that it may be Paraquat: Paraquat and concentrated herbicides are true time-critical medical emergencies. Call emergency medical services and your regional Poison Control center (1-800-222-1222 in the US) immediately so the receiving hospital can prepare Activated Charcoal (or Fuller's Earth / Bentonite) and alert their nephrology/hemoperfusion and intensive care teams before you arrive.
  2. CRITICAL FOR PARAQUAT: Tell paramedics and ER staff NOT to give routine supplemental oxygen: Unlike almost every other medical emergency, giving supplemental oxygen (O2) to a paraquat poisoning victim acts like pouring gasoline on a fire. Paraquat kills lung cells by using oxygen molecules to generate superoxide free radicals (O2-). Paramedics and emergency room staff must withhold supplemental oxygen unless the patient's pulse oximetry (SpO2) drops below 85 percent to 88 percent (partial pressure of oxygen PaO2 < 50 mmHg).
  3. Strip all contaminated clothing and flush skin and eyes for 15 to 20 minutes: If concentrated paraquat, diquat, or glyphosate splashed onto the skin or soaked through pants or boots during spraying, put on waterproof nitrile or rubber gloves, strip off all contaminated clothes, and wash the skin gently with copious running water and soap for 15 to 20 minutes. Do NOT scrub the skin harshly with a stiff brush: abrading the skin breaks the epidermal barrier and causes lethal systemic paraquat absorption through the bloodstream. Flush splashed eyes with lukewarm running water for at least 15 to 20 minutes.
  4. Understand the "Golden 60-Minute Window" for oral binding (Activated Charcoal / Fuller's Earth): Paraquat is absorbed rapidly from the small intestine, reaching peak blood levels within 60 to 120 minutes, after which it is actively pumped into the lungs where nothing can remove it. Getting the patient to an emergency room within the first 60 minutes to receive 50 to 100 grams of Activated Charcoal (or 15% Fuller's Earth / 7% Bentonite clay where stocked) is the single most effective step to prevent death. (Note: Only in remote agricultural settings hours away from any medical clinic, WHO field protocols state that if medical charcoal is unavailable, giving food-grade clay/bentonite or even clean soil/mud in water has been used as a desperate last-resort field binder for confirmed paraquat ingestion, though hospital activated charcoal is always preferred).
  5. Do not induce vomiting: Concentrated paraquat, diquat, and glyphosate-surfactant solutions are corrosive caustic chemicals that burn the mouth, pharynx, and esophagus. Forcing the person to gag or vomit brings the caustic herbicide back up the esophagus a second time, risking esophageal perforation and fatal aspiration into the lungs.
  6. Bring the herbicide container or photograph the exact chemical label: Take a photo of the "Active Ingredients" box and the EPA Registration Number on the jug (avoid carrying a leaking, contaminated chemical jug inside an ambulance cab unless sealed in heavy plastic). Over the years, brands like Roundup, Ortho, and Weedol have changed active ingredients between paraquat, diquat, glyphosate, glufosinate, and 2,4-D.

Why Supplemental Oxygen Accelerates Death in Paraquat Poisoning

Make sure every paramedic, nurse, and doctor caring for a paraquat patient sees this warning immediately: DO NOT administer routine supplemental oxygen (O2) to a patient with paraquat poisoning who has a normal or mildly reduced oxygen saturation (SpO2 >= 88%). Paraquat accumulates inside Type I and Type II alveolar lung cells at concentrations 10 to 50 times higher than in the bloodstream and undergoes continuous redox cycling, using intracellular oxygen (O2) and NADPH to manufacture millions of lethal superoxide (O2-) and hydroxyl (OH.) free radicals that destroy the lungs. Giving high-flow nasal oxygen or 100% oxygen accelerates this free-radical chain reaction and rapidly causes fatal pulmonary fibrosis. Supplemental oxygen is given only as a palliative or rescue measure when SpO2 falls below 85% to 88% (PaO2 < 50 mmHg).

Decision tree: Paraquat, diquat, and concentrated herbicide triage

flowchart TD
    Start["Suspected Herbicide Exposure (Oral Ingestion OR Concentrated Dermal/Ocular Splash)"] --> Identify["Check Container Label: Paraquat vs Diquat vs Glyphosate-Surfactant vs Glufosinate vs 2,4-D"]

    Identify --> RouteSplit{"What Was the Route of Exposure?"}

    RouteSplit -->|Skin or Eye Splash (Especially Backpack Sprayer Leak or Broken Skin)| DermalCare["1. Rescuer Gloves On; Strip All Clothing Immediately\n2. Wash Skin Gently with Soap & Water for 15-20 Min (NO Harsh Scrubbing)\n3. Irrigate Eyes 15-20 Min; Hospital Evaluation for Systemic Absorption if Skin Was Cut/Burned"]

    RouteSplit -->|Oral Ingestion (Intentional OR Accidental Storage in Drink Bottle)| ClassTriage{"Which Active Ingredient Was Swallowed?"}

    ClassTriage -->|1. Paraquat (Gramoxone, Parazone)| ParaquatPath["EXTREME EMERGENCY (Golden 1-Hour Window):\n1. WITHHOLD SUPPLEMENTAL OXYGEN (Keep SpO2 85-88% Unless PaO2 < 50 mmHg)\n2. Immediate Activated Charcoal (1 g/kg up to 50-100 g) or Fuller's Earth within 60 Min\n3. Aggressive IV Crystalloids + Urgent Charcoal Hemoperfusion / Hemodialysis within 2-4 Hours\n4. Immunosuppressive/Antioxidant ICU Bundle (IV Methylprednisolone + Cyclophosphamide + NAC)"]

    ClassTriage -->|2. Diquat (Reward, Reglone, Tribune)| DiquatPath["Severe Caustic + Renal + CNS Toxicity:\n1. Immediate Activated Charcoal / Fuller's Earth + Aggressive IV Fluid Resuscitation\n2. Monitor for Severe Paralytic Ileus (Fluid Sequestration in Gut), Acute Kidney Failure, Pontine Brainstem Infarction/Seizures\n3. Early Hemodialysis for Renal Failure (Less Selective Lung Uptake Than Paraquat, Still Avoid Excess O2)"]

    ClassTriage -->|3. Concentrated Glyphosate-Surfactant (41% Roundup Pro) or Glufosinate| GlyPath["Caustic + Surfactant Mitochondrial Toxicity:\n1. Do NOT Induce Vomiting; Check Airway for Pharyngeal Edema\n2. Aggressive IV Fluids for Hypovolemic/Cardiogenic Shock; Correct Severe Hyperkalemia & Metabolic Acidosis\n3. Early Hemodialysis if Oliguric Renal Failure, Acidosis, or Refractory Shock Develops\n4. For Glufosinate: Monitor 24-48h for Delayed Coma, Apnea, and Refractory Seizures"]

Comparing the Five Major Classes of Herbicides in Human Poisoning

While dozens of herbicides exist, five chemical classes account for nearly all life-threatening agricultural and household weed-killer emergencies worldwide:

Herbicide Class & Active Ingredients Common Brand Names & Formulations Primary Toxic Mechanism Key Clinical Organ Targets & Danger Signs Antidote / Specific Hospital Rescue
1. Paraquat (Bipyridylium Dichloride)
(20% to 24% agricultural liquid concentrate; banned in EU/UK/China/Brazil, restricted-use in US)		 Gramoxone SL, Parazone, Firestorm, Quik-Quat, Helmquat (Blue-green dark liquid with added stench/stenching agent and emetic). Active polyamine-transporter uptake into alveolar lung cells, followed by NADPH-dependent redox cycling that converts O2 into superoxide free radicals, destroying cell membranes via lipid peroxidation. Caustic oral/esophageal burns ("paraquat tongue"), acute renal tubular necrosis (within 24-48h), hepatic necrosis, and progressive irreversible pulmonary fibrosis (death in 1 to 21 days). WITHHOLD O2 (SpO2 target 85-88%); Activated Charcoal / Fuller's Earth within < 1 hour; Charcoal Hemoperfusion / Hemodialysis within 2 to 4 hours; IV Methylprednisolone + Cyclophosphamide + High-Dose NAC / Vitamin C / Salicylate.
2. Diquat (Bipyridylium Dibromide)
(2% to 37% liquid concentrate; widely sold where paraquat was banned)		 Reward, Reglone, Tribune, Weedol (older formulations), Harvester (Reddish-brown to dark yellow liquid). Undergoes redox cycling similar to paraquat, but lacks the polyamine uptake group so it is not actively concentrated in the lungs; instead devastates the GI tract, kidneys, and brainstem. Severe corrosive GI burns, massive third-space fluid loss into a paralyzed bowel (paralytic ileus), hypovolemic shock, rapid acute renal failure, and brainstem (pontine) hemorrhage/infarction, coma, and seizures. Activated Charcoal / Fuller's Earth immediately; massive IV fluid resuscitation (correcting liters lost into gut); Hemodialysis for acute kidney injury and electrolyte clearance; avoid hyperoxia.
3. Glyphosate + Polyethoxylated Tallow Amine (POEA) Surfactant
(1% to 2% Ready-to-Use Spray vs. 41% Agricultural Concentrate)		 Roundup (classic agricultural concentrates), Ranger Pro, Rodeo, Eraser Glyphosate itself inhibits plant EPSP synthase (absent in humans), but in concentrated (> 41%) ingestions, the POEA surfactant and potassium/isopropylamine salts disrupt human mitochondrial oxidative phosphorylation and burn mucosa. 1-2% Home Spray: Mild mouth/stomach irritation.
41% Concentrate (> 85 to 100 mL): Pharyngeal burns/airway swelling, intractable vomiting, severe hyperkalemia (especially in K+-salt formulations), metabolic acidosis, refractory shock, and acute renal failure.		 Early Endotracheal Intubation if stridor/pharyngeal burns; aggressive IV crystalloids + vasopressors; early Hemodialysis for severe metabolic acidosis, hyperkalemia, or oliguric acute kidney injury. (No Activated Charcoal if severe caustic burns).
4. Glufosinate Ammonium
(18% to 24% Concentrate)		 Finale, Rely, Liberty, Basta, Cheetah Structural analog of glutamate that inhibits glutamine synthetase, causing intracellular ammonia accumulation and central nervous system excitotoxicity. Deceptive 8-to-24-hour asymptomatic latency period, followed suddenly by profound coma, central respiratory arrest (apnea), retrograde amnesia, and refractory status epilepticus. Mandatory 24-to-48-hour ICU observation even if initially awake; early Activated Charcoal; early mechanical ventilation for central apnea; benzodiazepines/propofol for seizures; Hemodialysis in severe cases.
5. Chlorophenoxy Herbicides
(2,4-D [2,4-Dichlorophenoxyacetic acid], Dicamba, MCPA, MCPP)		 Weed-B-Gon, Killex, Crossbow, Banvel Uncouples oxidative phosphorylation, disrupts acetyl-CoA metabolism, and causes direct skeletal muscle membrane toxicity (massive rhabdomyolysis). Vomiting, abdominal pain, myotonia, massive rhabdomyolysis (sky-high CK and dark brown myoglobinuric urine), hyperthermia, metabolic acidosis, coma, and ventricular arrhythmias. Intravenous Sodium Bicarbonate Urinary Alkalinization (raising urine pH to 7.5 to 8.0 traps weak-acid 2,4-D in the urine, increasing renal clearance 10-fold to 20-fold while protecting kidneys from myoglobin) + Hemodialysis for severe toxicity.

Deep Dive: Paraquat Poisoning: Pathophysiology, Clinical Stages, and the Oxygen Rule

1. Why Paraquat Selectively Destroys the Lungs (The Polyamine Transporter Trap)

When paraquat enters the bloodstream from the gut or through damaged skin, it is distributed to all organs, causing early necrosis in the proximal renal tubules of the kidneys and the liver. However, the lungs suffer a unique, fatal fate: - Type I and Type II alveolar epithelial cells in the human lung possess an energy-dependent membrane transport system called the polyamine uptake system (normally used to import endogenous polyamines like putrescine and spermine). - Because the distance between the two positively charged nitrogen atoms on the paraquat molecule (0.7 nanometers) is structurally identical to natural polyamines, the lungs mistakenly vacuum paraquat out of the bloodstream against a massive concentration gradient, reaching lung tissue concentrations 10 to 50 times higher than plasma levels within hours. - Once trapped inside alveolar cells, paraquat (PQ2+) accepts an electron from NADPH (catalyzed by NADPH-cytochrome P450 reductase) to become a paraquat monocation free radical (PQ.+). - This radical instantly transfers its extra electron to molecular oxygen (O2), regenerating the original paraquat ion (PQ2+) while creating a highly destructive superoxide anion radical (O2.-), hydrogen peroxide (H2O2), and hydroxyl radicals (OH.). - This continuous redox cycling consumes all cellular NADPH and glutathione, peroxidizes cell membrane lipids, triggers severe alveolitis (lung inflammation) within 24 to 72 hours, and stimulates massive proliferation of fibroblasts and collagen that turn the spongy air sacs of the lungs into solid, non-breathing scar tissue (honeycomb pulmonary fibrosis) over 5 to 21 days.

2. Why Kidney Survival Determines Lung Survival

Paraquat is not metabolized in the human body; more than 90 percent of absorbed paraquat is excreted unchanged by the kidneys via both glomerular filtration and active tubular secretion within the first 12 to 24 hours, provided kidney function stays normal. - However, paraquat simultaneously causes acute tubular necrosis (ATN) of the kidneys inside the first 24 hours. - As soon as the kidneys fail, urinary paraquat excretion stops, plasma paraquat levels stay elevated for days, and the lungs continue vacuuming paraquat out of the blood until a lethal pulmonary burden is reached. - Therefore, aggressive intravenous fluid resuscitation to maintain high urine output and ultra-early extracorporeal blood purification (Charcoal Hemoperfusion or Hemodialysis within 2 to 4 hours of ingestion) are vital to clear paraquat from the blood before renal failure locks it inside the body.

3. The Three Dose-Dependent Clinical Tiers of Paraquat Ingestion

Dose Swallowed (mg/kg of Paraquat Ion) Equivalent Volume of 20% Liquid Concentrate (such as Gramoxone) Clinical Course, Organ Involvement, and Prognosis
Tier 1: Mild-to-Moderate Ingestion
(< 20 mg/kg of paraquat ion)		 Less than 7.5 mL (< 1.5 teaspoons) in a 70 kg adult Oral and pharyngeal burning, nausea, vomiting, diarrhea. Mild reversible renal or hepatic dysfunction; most patients recover fully if treated within the first hour with activated charcoal and IV fluids.
Tier 2: Severe Ingestion (Subacute Pulmonary Fibrosis)
(20 to 40 mg/kg of paraquat ion)		 7.5 mL to 15 mL (1.5 teaspoons to 1 tablespoon / one mouthful) in a 70 kg adult Day 1 to 2: Severe caustic pseudomembranous burns of the tongue ("paraquat tongue") and esophagus, vomiting, painful swallowing.
Day 2 to 5: Acute oliguric renal failure and hepatitis.
Day 5 to 21: Progressive dyspnea, bilateral lung infiltrates, and relentless pulmonary fibrosis leading to fatal hypoxemic respiratory failure in the majority of cases.
Tier 3: Fulminant Ingestion (Multiorgan Necrosis)
(> 40 to 50 mg/kg of paraquat ion)		 More than 15 mL to 20 mL (> 1 tablespoon / multiple gulps) in a 70 kg adult Rapid onset of fiery gastrointestinal necrosis, esophageal perforation (mediastinitis), severe high-anion-gap lactic acidosis, cardiogenic/vasoplegic shock, adrenal cortical necrosis, acute renal/hepatic failure, coma, and death within 12 to 72 hours from multiorgan failure before pulmonary fibrosis even has time to develop.

4. Dermal (Skin) and Ocular Paraquat Exposure Hazards

Never underestimate skin exposure to paraquat: - While intact, healthy skin absorbs paraquat slowly, prolonged contact with paraquat-soaked trousers or boots (such as a leaking backpack sprayer on a farmer's back, buttocks, and scrotum) causes direct caustic chemical burns and ulceration of the skin. - Once the outer stratum corneum is burned, cut, scratched, or eczematous, paraquat absorbs rapidly into the systemic bloodstream through the damaged skin, and numerous fatal cases of pulmonary fibrosis have occurred strictly from dermal backpack-sprayer leaks without a single drop being swallowed. - Eye splashes with concentrated paraquat cause delayed, severe corneal and conjunctival epithelial sloughing peaking 12 to 48 hours after exposure, requiring immediate 20-minute water/saline irrigation and urgent ophthalmology care to prevent permanent corneal scarring and blindness.

Stepwise Hospital and ICU Protocol for Paraquat and Diquat

  1. Strict Oxygen Restriction (SpO2 Target 85% to 88%):
  2. Place a visible bedside sign above the patient's head: "PARAQUAT POISONING: DO NOT ADMINISTER SUPPLEMENTAL OXYGEN UNLESS SpO2 < 85% (PaO2 < 50 mmHg)."
  3. Keep the patient breathing room air (FiO2 21%) as long as possible.
  4. Immediate Gastrointestinal Decontamination (Within 60 Minutes):
  5. Administer Activated Charcoal (1 to 2 g/kg, or 50 to 100 grams in adults) orally or via a carefully placed soft nasogastric tube (alternatively 15% Fuller's Earth [100 to 150 g] or 7% Bentonite plus a cathartic like mannitol/sorbitol if using clay). Modern clinical toxicology studies confirm that Activated Charcoal is just as effective as Fuller's Earth and is already stocked in every emergency department; never delay charcoal waiting to locate Fuller's Earth.
  6. Avoid routine gastric lavage after caustic paraquat ingestion due to the high risk of esophageal perforation, unless performed gently via nasogastric aspiration within 30 to 60 minutes of a massive liquid ingestion.
  7. Aggressive Intravenous Crystalloid Hydration:
  8. Infuse isotonic crystalloids (0.9% Normal Saline or Lactated Ringer's) at 150 to 250 mL/hour to maintain brisk urine output (1.5 to 3 mL/kg/hour) and maximize endogenous renal paraquat clearance during the critical first 24 hours.
  9. Early Charcoal Hemoperfusion (HP) or Hemodialysis (HD): The 2-to-4-Hour Window:
  10. Charcoal Hemoperfusion (or High-Flux Hemodialysis) can clear paraquat from the bloodstream, but ONLY while paraquat is still circulating in the plasma before it is locked inside lung cells.
  11. To improve survival in borderline-lethal ingestions, Charcoal Hemoperfusion (or Hemodialysis) must be initiated within 2 to 4 hours (and no later than 6 hours) post-ingestion, often followed by Continuous Venovenous Hemofiltration (CVVH). Once 12 to 24 hours have passed, blood paraquat levels are already low because the toxin is inside the lungs, and dialysis serves only to support acute renal failure.
  12. Rapid Bedside Diagnostic Confirmation (Urine Sodium Dithionite Test & Plasma Nomogram):
  13. Urine Sodium Dithionite Colorimetric Test: Adding 1 gram of sodium bicarbonate and 1 gram of sodium dithionite to 10 mL of the patient's urine reduces paraquat to its blue free-radical ion (and reduces diquat to a bright yellow-green ion).
    • If the urine turns dark navy blue or blue-black within 6 to 24 hours of ingestion, it confirms a massive systemic paraquat burden with very high mortality.
    • If the urine stays clear or pale light blue, systemic absorption is low and survival is likely.
  14. Quantitative Plasma Paraquat Nomogram (Proudfoot / Hart Nomograms): Plotting the exact quantitative plasma paraquat concentration (mcg/mL or mg/L) against hours since ingestion predicts survival probability.
  15. Immunosuppressive and Antioxidant ICU Rescue Regimen:
  16. To blunt the intense pulmonary alveolitis and fibroblast collagen deposition, many international toxicology centers (particularly across Asia-Pacific and in WHO/NPIS clinical guidance) administer an early immunosuppressive and antioxidant protocol in moderate-to-severe paraquat poisoning:
    • Intravenous Pulse Methylprednisolone (15 mg/kg/day or 1,000 mg IV daily for 3 days) + Intravenous Cyclophosphamide (15 mg/kg/day IV for 2 days), followed by Dexamethasone (8 mg IV every 8 hours).
    • High-Dose Intravenous N-Acetylcysteine (NAC) (to replenish intracellular glutathione), High-Dose Vitamin C (Ascorbic Acid), Vitamin E, and Sodium Salicylate (which chelates iron, scavenges hydroxyl radicals, and inhibits NF-kappaB lung inflammation).
  17. Pain Relief and Palliative Care:
  18. Caustic oral, pharyngeal, and esophageal ulcers ("paraquat tongue") cause excruciating pain; provide generous intravenous opioid analgesia (morphine or fentanyl) and lidocaine viscous oral rinses, and keep the patient nil-by-mouth (NPO) with parenteral nutrition if severe esophageal burns are present.

Concentrated Glyphosate-Surfactant ("Roundup") Poisoning Triage

Because glyphosate is the most widely used herbicide in the world, poison centers distinguish sharply between dilute ready-to-use homeowner sprays and agricultural concentrates:

  • Homeowner Ready-to-Use (RTU) Spray (1% to 2% Glyphosate): Accidental swallows of a mouthful by a child or adult typically cause only self-limited mouth irritation, mild nausea, vomiting, or diarrhea that resolves with oral fluids and observation.
  • Agricultural / Commercial Concentrate (41% to 50%+ Glyphosate + 15% POEA Surfactant):
  • Swallowing more than 85 mL to 100 mL (3 ounces) of concentrated 41% glyphosate-surfactant is a life-threatening critical care emergency with a mortality rate of 10 to 30 percent in intentional overdoses.
  • Furthermore, certain high-strength commercial glyphosate formulations use Glyphosate Potassium Salt (K+ salt) instead of isopropylamine salt: swallowing a concentrated potassium-glyphosate product delivers a massive exogenous potassium load that can cause immediate fatal hyperkalemic cardiac arrest within 1 to 3 hours.
  • Hospital Management: Perform immediate flexible nasopharyngoscopy and early endotracheal intubation if drooling, stridor, or pharyngeal edema is present; restore blood pressure with aggressive IV crystalloids and norepinephrine; treat hyperkalemia immediately with IV calcium, insulin-dextrose, and sodium bicarbonate; and initiate early hemodialysis if refractory metabolic acidosis, hyperkalemia, oliguric acute kidney injury, or shock persists.

Prevention: The #1 Cause of Accidental Fatal Herbicide Ingestion

Never Pour Weed Killer Into a Water, Soda, or Sports Drink Bottle

Across the United States, Europe, Latin America, and Asia, virtually 100 percent of accidental fatal paraquat, diquat, and concentrated glyphosate poisonings happen the exact same way: someone transfers leftover dark blue-green or brown liquid herbicide into an empty Gatorade, Coca-Cola, iced tea, beer, or bottled water container and leaves it in a garage, barn, or pickup truck bed, where a thirsty child or coworker takes a single big gulp thinking it is a drink. Never transfer any pesticide or herbicide out of its original labeled container, and lock all agricultural concentrates inside a ventilated chemical cabinet.

Regional emergency numbers and agency protocols

Region / Country Emergency Ambulance Number National Poison Control Helpline Official Clinical Protocol Notes
United States & Canada 911 US: 1-800-222-1222 (America's Poison Centers) / Canada: 1-844-POISON-X (1-844-764-7669) US EPA mandates that Paraquat is a Restricted Use Pesticide (RUP) with closed-system transfer; AAPCC/EPA guidelines direct immediate activated charcoal, withholding O2 (SpO2 < 88%), and urgent nephrology consultation.
United Kingdom 999 (or 112) NHS 111 (Public) / NPIS TOXBASE (0344 892 0111 for clinicians) Paraquat and diquat sales are banned in the UK, though legacy barn stocks exist; NPIS TOXBASE provides proudfoot nomogram interpretation, urine dithionite testing, and immunosuppressive protocols.
European Union 112 Contact national poison center via 112 (e.g., Germany +49 30 19240, France 01 40 05 48 48) Paraquat (since 2007) and diquat (since 2018) are banned across the EU; glyphosate, glufosinate, and 2,4-D remain prevalent in agricultural exposures.
Australia & New Zealand Australia: 000 / New Zealand: 111 Australia: 13 11 26 (Poisons Information Centre) / New Zealand: 0800 764 766 (0800 POISON) Paraquat (Gramoxone) remains a restricted S7 poison in agricultural use; Australian Therapeutic Guidelines emphasize immediate oral activated charcoal within 1 hour and strict avoidance of supplemental oxygen.
India & Asia-Pacific India: 112 (or 108) / Sri Lanka/Thailand: 1990 / 1669 India: AIIMS National Poisons Information Centre (1800-116-117 / 011-26589391) High regional burden of paraquat (24% SL) and glyphosate exposures; immediate activated charcoal/Fuller's earth, early charcoal hemoperfusion within 4 hours, and pulse methylprednisolone/cyclophosphamide.

Frequently asked questions

Why must paramedics and emergency doctors withhold supplemental oxygen from someone who swallowed paraquat?

Paraquat kills lung cells through a chemical process called redox cycling, which uses oxygen molecules inside the lungs to manufacture millions of destructive superoxide and hydroxyl free radicals. Because the lungs actively pump paraquat out of the bloodstream to concentrations 10 to 50 times higher than anywhere else in the body, giving supplemental oxygen supplies extra fuel to that chemical reaction and drastically speeds up fatal lung scarring (pulmonary fibrosis). Medical teams must keep paraquat patients breathing normal room air and only give supplemental oxygen if blood oxygen saturation (SpO2) drops below 85 to 88 percent (PaO2 below 50 mmHg).

Why is the first 60 minutes after swallowing paraquat called the "Golden Hour"?

Paraquat is absorbed very quickly from the small intestine, reaching peak levels in the bloodstream within 60 to 120 minutes, and is then actively pumped into lung cells where no antidote or dialysis machine can ever pull it back out. Swallowing Activated Charcoal (or Fuller's Earth / Bentonite clay) within the first 60 minutes binds the liquid paraquat inside the stomach and intestines before it can enter the bloodstream, which can mean the difference between survival and fatal lung fibrosis.

Can you get fatal paraquat poisoning just from spilling it on your skin without swallowing any?

Yes. Concentrated paraquat is a corrosive chemical that burns and blisters skin on contact. If paraquat leaks from a backpack sprayer onto a worker's back, legs, or groin, or splashes onto skin that already has cuts, scrapes, abrasions, or rashes, it rapidly passes through the damaged skin barrier into the bloodstream and travels to the lungs, causing the exact same fatal pulmonary fibrosis as swallowing the poison. If paraquat touches the skin, strip off all clothing immediately and wash gently with soap and running water for 15 to 20 minutes without scrubbing hard (scrubbing scrapes the skin and speeds up absorption).

What is the difference between household ready-to-use Roundup spray and agricultural Roundup concentrate if accidentally swallowed?

Ready-to-use household garden spray bottles contain only 1% to 2% glyphosate diluted in water; an accidental small swallow typically causes only mild mouth irritation or an upset stomach. In contrast, agricultural or commercial herbicide jugs contain 41% to 50% glyphosate mixed with concentrated surfactants (such as POEA) and sometimes high-dose potassium salts. Swallowing more than 85 mL (about 3 ounces) of concentrated 41% glyphosate-surfactant can cause severe throat burns, airway swelling, life-threatening high blood potassium (hyperkalemia), metabolic acidosis, kidney failure, and shock requiring intensive care.

What is "paraquat tongue" and when does it appear?

Because concentrated paraquat and diquat are powerful caustic chemicals, swallowing even a small amount causes severe chemical burns of the mouth, tongue, and throat. Within 24 to 48 hours after ingestion, the surface of the tongue swells, blisters, and sloughs off, becoming covered in painful white-yellow necrotic plaques and bleeding ulcers known clinically as "paraquat tongue." Even if the patient spits out most of the liquid, the appearance of oral burns confirms exposure and requires immediate hospital admission to monitor kidney and lung function.

Sources and official guidance

  • United States Environmental Protection Agency (EPA): Recognition and Management of Pesticide Poisonings (6th Edition): Paraquat, Diquat, Glyphosate, and Chlorophenoxy Herbicides.
  • World Health Organization (WHO) & Food and Agriculture Organization (FAO): Clinical Management of Paraquat and Bipyridylium Herbicide Poisoning.
  • Centers for Disease Control and Prevention (CDC): Emergency Preparedness and Response: Facts About Paraquat Chemical Emergencies and Decontamination.
  • National Poisons Information Service (NPIS, United Kingdom): TOXBASE Clinical Management of Paraquat, Diquat, Glyphosate, and Glufosinate Poisoning.
  • EXTRIP (Extracorporeal Treatments in Poisoning) & International Clinical Toxicology Guidelines: Early Hemoperfusion, Hemodialysis, and Immunosuppressive Therapy in Paraquat and Chlorophenoxy Herbicide Poisoning.

This guide is for informational purposes and does not replace professional medical evaluation, Poison Control consultation, or hospital intensive care. Because concentrated herbicide exposures can cause rapid airway burns, shock, and respiratory failure, we strongly recommend taking an accredited hands-on first aid and CPR course through the International Federation of Red Cross and Red Crescent Societies (IFRC), your national Red Cross society, St John Ambulance, or a certified local provider.