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Burns caused by giant hogweed


Giant hogweed is a poisonous exotic plant. The sap of giant hogweed contains toxins that are activated by light (natural or artificial UV rays). Contact with giant hogweed sap, combined with exposure to light, causes pain and skin lesions similar to burns.


Painful and sometimes serious lesions may appear up to 48 hours after skin comes into contact with giant hogweed sap. Lesions are characterized by:

  • Redness and swelling of the skin
  • Blisters
  • Superficial or more serious (first or second-degree) burns

All parts of the body can be affected by sap toxins and light. However, the following parts are especially vulnerable:

  • The back of hands
  • Arms
  • Legs
  • Eyes
  • Face

When to consult

You should see a doctor if:

  • A child has come into contact with sap
  • Sap goes into someone’s eyes
  • The individual affected has fever
  • Lesions are serious:
    • Skin becomes red and swollen on over a third of body part with lesions
    • There are large blisters (at least 2.5 cm or bigger than a quarter coin)
    • Lesions appear on several parts of the body
    • Lesions contain pus (opaque, yellow liquid)


If sap comes into contact with your skin

  • Remove sap as fast as possible with a paper towel, without rubbing. Avoid spreading sap on skin.
  • Rinse area of skin affected with water and soap and wash your hands.
  • Remove clothing and wash them to avoid contaminating other parts of your body or objects.
  • Avoid exposing affected areas of your skin to natural or artificial light. Wear gloves, pants and a long-sleeve shirt for at least 48 hours. If you have burns, cover affected areas for a week.
  • Use a sunscreen with a sun protection factor (SPF) of at least 30 for 6 months.

If giant hogweed sap goes into your eyes

  • Rinse your eyes thoroughly with clear water for at least 10 minutes
  • Wear sunglasses with dark lenses to avoid exposing your eyes to light
  • See a doctor as soon as possible

If you have burns on your skin

First-degree burns are superficial and generally do not require specific treatment. If you have pain:

  • Take a bath in cool water
  • Prepare compresses and soak them in water. Apply the compresses on your burns for 20 minutes, 4 to 6 times a day

If you have second-degree burns with blisters, contact Info-Santé 811 to obtain further information on treatment of burns. You can also see your doctor for a prescription of appropriate treatment.


Lesions take about a week to heal. Then scars or dark spots may appear on the skin and remain visible for several years.

The affected area may also remain sensitive to light for several months.

Protection and prevention

For further information on ways to identify and handle giant hogweed, read Identifying and getting rid of giant hogweed This hyperlink will open in a new window..

People at risk

Some people are more at risk of coming into contact with giant hogweed sap. They include:

  • Children, who can play with the plant or use it for hiding
  • Parents, who can come into contact with the sap by touching their children and contaminated clothing
  • Horticulturalists
  • Farmers
  • Workers clearing brush
  • People that live in or frequent areas where the plant grows

People often contact with giant hogweed sap during outdoor activities such as gardening and hiking. Sap can also stick to animal fur, especially dogs, who can then directly contaminate people who touch them.

Last update: June 13, 2023


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