Giant hogweed is an invasive perennial. It grows in moist areas along roadsides, ditches and streams and in open fields and woodlands. The plant spreads easily and does grow in Ontario.
Giant hogweed can grow to a height of 2 to 5 ½ metres. The plant has a thick, hollow stem that is covered in reddish-purple flecks and stiff hairs. The hairs are filled with a watery, clear sap. Sap can also be found in the stalks attached to the leaves, roots, seeds and flowers of the plant. The flowers are umbrella-shaped and white in colour and appear similar to Queen Anne’s Lace (a wildflower). Giant hogweed only flowers once in its lifetime, producing thousands of winged seeds that are spread by the wind.
What is the reaction caused by the sap?
The reaction occurs after you come into contact with the sap. The sap contains chemicals called furanocoumarins. These chemicals, when exposed to sunlight (UV radiation), cause a reaction known as phytophotodermatitis.
What does the reaction look like?
The initial reaction can occur within 15 minutes of being in the sun.
Redness and blisters can develop within 48 hours of exposure to sunlight. The severity of the reaction will depend on how long you remain in the sun.
The longer the sap remains on your skin the more sensitive the skin will be to the sunlight. Your skin can remain sensitive to the sun several months after exposure to giant hogweed.
What to do if you come into contact with giant hogweed?
- Wash the area with soap and cool water.
- Do not use warm water as this opens up pores and allows deeper penetration of the chemicals.
- Keep skin covered to protect it from sunlight.
- If you develop a rash or blisters seek medical attention. The treatment is dependent on how severe the reaction/burns are.
- Seek immediate medical attention if you get the sap in your eyes or you inhale sap particles.
If you have any questions about giant hogweed please call one of our pharmacists.
