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Paraquat poisoning

Definition

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 poisoning caused by breathing in or swallowing 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 the local emergency number (such as 911), or the local poison control 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; Dipyridylium poisoning

Poisonous Ingredient

Paraquat (a bipyridyl compound)

Where Found

Paraquat is found in certain commercial herbicides used for weed control. In the United States, it is classified as a restricted-use chemical, meaning that only licensed individuals can purchase and apply it.

Symptoms

Symptoms of paraquat poisoning include:

Severe exposure can cause:

Before Calling Emergency

Have the following information ready:

Take the container with you to the hospital, if possible.

Poison Control

The local poison control 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 national hotline 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.

You can also get online poison help now at Poisonhelp.org. Just enter the product, poison, or medicine to get expert help.

What to Expect at the Emergency Room

Your health care provider will measure and monitor your vital signs, including temperature, pulse, breathing rate, and blood pressure. Tests that may be done include:

Treatment may include:

Outlook (Prognosis)

The outcome depends on the amount of paraquat absorbed. Ingestion of even a small amount can be fatal. People with mild exposure may recover fully, but those who swallow the poison often develop fatal organ damage.

Breathing in paraquat may cause lung damage. Long-term exposure to paraquat may cause scarring of the lungs called pulmonary fibrosis. This makes it hard to breathe.

Paraquat causes damage to the body when it touches the lining of the mouth, stomach, or intestines. Paraquat may also damage the kidneys, liver, and esophagus (the tube that 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 (mediastinum).

References

Kuschner WG, Blanc PD. Acute responses to toxic exposures. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 6th ed. Philadelphia, PA: Elsevier; 2022:chap 103.

Meehan TJ. Care of the poisoned patient. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 135.

Welker KL, Thompson TM. Pesticides. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 152.

Review Date: 7/1/2025
Reviewed By: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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