What is paraquat?

Paraquat is a chemical herbicide, or weed killer, that’s highly toxic and used all over the world. It’s also known by the brand name Gramoxone.

Paraquat is one of the most common herbicides used today, but it can cause fatal poisoning when ingested or inhaled.

It’s primarily used to control weed and grass growth. In the United States, only individuals who have been licensed to handle it are given access to the chemical. Paraquat poisoning is not a common occurrence in the United States. It is, however, a leading cause of fatal poisoning in parts of Asia, the Pacific Islands, and South and Central Americas. It’s reported that more than 70 percent of paraquat poisonings result in death.

Paraquat poisoning is a fast process, and symptoms develop quickly.

Immediately after ingesting or inhaling a toxic amount of paraquat, an individual is likely to have swelling and pain in the mouth and throat. Paraquat causes immediate damage by direct contact. Soon after, they may experience:

  • nausea
  • abdominal pain
  • vomiting
  • diarrhea that may be bloody

The gastrointestinal symptoms are often severe. They can lead to both dehydration and low blood pressure. One may also experience nosebleeds and difficulty breathing.

Even ingesting small to medium amounts of paraquat can lead to fatal poisoning. Within several weeks to several days after ingesting a small amount, the person may experience lung scarring and the failure of multiple organs. This includes heart failure, respiratory failure, kidney failure, and liver failure.

Ingesting large amounts of paraquat will cause severe symptoms within several hours to several days. These symptoms include:

  • confusion
  • muscle weakness
  • seizures
  • respiratory failure and difficulty breathing
  • fast heart rate
  • coma

Several hours after ingesting or inhaling large amounts, paraquat poisoning can cause:

  • acute kidney failure
  • liver failure
  • lung scarring
  • pulmonary edema
  • respiratory failure

Paraquat poisoning most often comes from swallowing the chemical. This can occur after consuming contaminated food or beverages. Workers who are frequently around the chemical are also susceptible to poisoning that can lead to lung damage. In the past, some batches of marijuana were found to have traces of paraquat, which when inhaled could lead to poisoning.

It’s also possible to be poisoned after skin exposure. This is most likely when the contact is prolonged and the chemical concentration of the paraquat is high. It’s also more common if the chemical makes contact near a cut, sore, or rash.

Paraquat poisoning is also a leading means of suicide, particularly in countries where its use is unregulated. Regulations of paraquat appear to be reducing the number of paraquat-related suicide deaths. It’s estimated that around 30 percent of the world’s suicides are from pesticide self-poisoning.

If you believe that you or your child may have been poisoned by paraquat, seek out emergency medical attention immediately. If you have the food that you believe poisoned you, take it with you to the hospital for testing.

Your doctor may order immediate blood or urine tests to check for levels of the chemical. Blood tests can also help evaluate organ damage. These tests will also help them evaluate and monitor your overall health, looking at factors like hydration, electrolyte levels, and any worsening organ function.

At the hospital, the first focus will be on eliminating the paraquat from your system. If the ingestion was recent, they will give you activated charcoal, either to take orally or through a nasal tube. This may help absorb the chemical and decrease the amount that is taken up by your body.

If the paraquat poisoning is more advanced, your doctors may order a hemoperfusion. This procedure attempts to filter blood through charcoal to try to remove the paraquat from the system (particularly the lungs).

You’ll also be given fluids and electrolytes through an IV to keep you hydrated. If your breathing becomes labored or difficult, you’ll be given support from a breathing machine.

Doctors will continue to test your blood and urine and monitor vital signs to watch for damage caused by the poisoning. They’ll order a chest X-ray or CT scan to evaluate for lung injury. They may also keep you attached to a heart monitor or order an EKG to evaluate your heart’s functioning.

As symptoms arise, your doctors will administer medications and medical interventions to address them. This may include anti-vomiting medications for the digestive upset and anti-seizure medications for seizures that occur.

It’s often not possible to reverse damage that’s occurred or avoid long-term consequences. That being said, early treatment can allow someone to avoid permanent side effects of the poisoning. Unfortunately, paraquat is highly toxic and there’s no cure or antidote.

Paraquat poisoning is often fatal. Death is highly likely if you’ve ingested the chemical and don’t seek out immediate medical attention. The outlook ultimately depends on how severe the exposure was, the health of the individual, and how quickly the individual sought out medical attention.

Some people who survive paraquat poisoning will develop breathing symptoms, but have an otherwise full recovery. Many have long-term or permanent damage and scarring in their lungs. Esophageal strictures (or scarring in the esophagus) is also a common side effect; this makes it difficult for the person to swallow.

While there are management options available for paraquat poisoning, it’s vastly preferable to avoid the poisoning all together. Fortunately, there are methods of prevention you can follow to decrease the likelihood of ingesting or inhaling the chemical. These include:

  • Avoid areas that you know use paraquat or herbicides.
  • Wash all produce thoroughly with clean water before consuming it.
  • In areas known for paraquat usage, only drink bottled water and other pre-packaged beverages.
  • If you believe food or drink has been in contact with paraquat, don’t consume it.
  • If you work with paraquat, make sure to read all chemical labels carefully; shower immediately after using the chemical.
  • If you think you’ve come in contact with liquid paraquat, remove any clothing immediately. Try to avoid touching the areas of clothing that have been contaminated. Wash off any paraquat from the skin with large amounts of soap and water. If you wear contact lenses, remove them after washing your hands thoroughly and dispose of them with the clothing. Wash your entire body with soap and water.

If you believe you’ve been affected by paraquat poisoning, seek immediate emergency medical attention. If you work regularly with paraquat and worry about contamination, make sure you know how to manage any possible exposure.