Paraquat poisoning

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Paraquat (dipyridylium) is a highly toxic weed killer (herbicide). In the past, the United States encouraged Mexico to use it to destroy marijuana plants. Later, research showed this herbicide was dangerous to workers who applied it to the plants.

This article discusses the health problems that can occur from swallowing or breathing in Paraquat.

This article is for information only. Do NOT use it to treat or manage an actual poison exposure. If you or someone you are with has an exposure, call your local emergency number (such as 911), or your local poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.

Alternative Names

Paraquat lung


In the United States, Paraquat is classified as "restricted commercial use." People must obtain a license to use the product.

Breathing in Paraquat may cause lung damage and can lead to a disease called Paraquat lung. Paraquat causes damage to the body when it touches the lining of the mouth, stomach, or intestines. You can get sick if Paraquat touches a cut on your skin. Paraquat may also damage the kidneys, liver, and esophagus (the tube food goes down from your mouth to your stomach).

If Paraquat is swallowed, death can quickly occur. Death may occur from a hole in the esophagus, or from severe inflammation of the area that surrounds the major blood vessels and airways in the middle of the chest.

Long-term exposure to Paraquat may cause scarring of the lungs called pulmonary fibrosis. This makes it hard to breathe.


Symptoms of Paraquat poisoning include:

Exams and Tests

You will be asked if you have been exposed to Paraquat. Take the container with you to the hospital, if possible.

The health care provider will measure and monitor your vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated. You may receive:

  • Activated charcoal by mouth or a tube through your nose into your stomach.
  • Blood and urine tests
  • Breathing support, including oxygen, tube through the mouth into the throat, and breathing machine
  • Chest x-ray
  • EKG (electrocardiogram, or heart tracing)
  • Fluids through a vein (by IV)
  • Medicine to treat symptoms


There is no specific treatment for Paraquat poisoning. The goal is to relieve symptoms and treat complications. This includes:

  • Removing all contaminated clothing.
  • If the chemical touched your skin, wash the area with soap and water for 15 minutes. Do not scrub hard, because that could break your skin and let more of the Paraquat absorb into your body.
  • If the Paraquat got into your eyes, flush them with water for 15 minutes.
  • If you have swallowed Paraquat, get treated with activated charcoal as quickly as possible. Sicker people may need a procedure called hemoperfusion, which filters the blood through charcoal to try to remove Paraquat from the lungs.

Outlook (Prognosis)

The outcome depends on how severe the exposure is. Some people may develop mild breathing-related symptoms and have a full recovery. Others may have permanent changes in their lungs. If a person swallowed the poison, death is likely without immediate medical care.

Possible Complications

These complications can occur from Paraquat poisoning:

  • Lung failure
  • Holes or burns in the esophagus
  • Inflammation in the chest between the lungs
  • Kidney failure
  • Scarring of the lungs

When to Contact a Medical Professional

If you believe you have been exposed to Paraquat, seek medical care right away.

Your local poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This hotline number will let you talk to experts in poisoning. They will give you further instructions.

This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.


Read labels on all chemical products. Do NOT use any that contain Paraquat. Stay away from areas where it may be used.


Cannon RD, Ruha A-M. Insecticides, herbicides, and rodenticides. In: Adams JG, ed. Emergency Medicine. 2nd ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 146.

Rhee JW. Pesticides. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 163.

Robbe WC III, Meggs WJ. Insecticides, herbicides, rodenticides. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 182.

Version Info

  • Last reviewed on 10/9/2015
  • Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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