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Health Hazards & Safety Instructions for Giant Hogweed (with graphic photos)

When giant hogweed (GH) sap, which contains photosensitizing furanocoumarins, contacts human skin in conjunction with sunlight, it can cause phytophotodermatitis - a serious skin inflammation. In brief, the sap prevents your skin from protecting itself from sunlight which leads to a very bad sunburn. Heat and moisture (sweat or dew) can worsen the skin reaction. The phototoxic reaction can begin as soon as 15 minutes after contact, with sensitivity peak between 30 minutes and two hours after contact.

burns 5, 6 and 7 days after contact with giant hogweed sap burns 8 and 9 days and 5 months after contact with giant hogweed sap

Photo of giant hogweed burn - 5 days to 5 months after initial exposure. Photo credit: Bob Kleinberg

The Symptoms of Exposure to Giant Hogweed Sap

  • Painful blisters that form within 48 hours and become dark and pigmented
  • Scars that last up to six years, though typically only last a few months
  • Long-term sensitivity to sunlight is common

Where the Toxic Sap is Located

  • Sap can be located in all parts of the plant but the following have higher concentrations: the lower part of the hollow stems and petioles; the hollow hairs on the plant; the foliage, stem, flower, or fruit (seed).

Safety Precautions for Controlling Giant Hogweed

  • Refer to the How to Control GH webpage which includes a detailed guide
  • Do not touch the plant with bare skin
  • Do not touch your bare skin with sap covered gloves
  • Prevent UV sunlight from reaching skin by:
    • Wearing long waterproof gloves, long sleeves, pants, boots, and eye protection; synthetic water-resistant materials are best since cotton and linen fibers can soak up the plant sap and be penetrated by plant hairs
    • If controlling plants with multiple people, keep a good distance from one another as the sap can splash three to four feet
    • Apply sun block before beginning work
  • Launder clothes that may have contacted plants
  • Wash equipment with water immediately after use
  • Limit exposure to sunlight after control OR work around giant hogweed plants after sunset
  • DO NOT use a "weed-whacker" or brush cutter - sap may splatter as stems are cut
  • Keep water, soap, and eye-wash near work area in case of exposure

What to do if you are Exposed to Giant Hogweed

  • Wash the affected area thoroughly with soap and COLD water as soon as possible
  • Keep exposed area away from sunlight for 48 hours
  • If a reaction occurs, topical steroids applied early can reduce the severity of the reaction and ease discomfort
  • If sap goes in eyes, rinse them with water and wear sunglasses
  • If a reaction has occurred, the area of skin may be sensitive to sunlight for a few years and you may want to apply sun block or keep the affected area covered from the sun when possible
  • See a physician if you have a reaction or any questions

  • Contact for this Page
  • Giant Hogweed
    Forest Health and Protection Program
    Division of Lands & Forests
    21 South Putt Corners Road
    New Paltz, NY 12561
    Send us an email
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