The dangerous plants lurking near rivers that could send you to A&E

Unknown to many, Giant Hogweed is a highly hazardous plant with phototoxic sap, which can cause severe burns, blisters and long-term scarring.

In partnership with the River Stewardship Company, we have been managing Giant Hogweed along Sheffield’s five rivers for around 15 years, thanks to support from local businesses and agencies.

Below, I've answered some of the key questions about Giant Hogweed and how you can stay safe this summer.  

Why is Giant Hogweed a risk? 

Aside from the health risk the plant poses, Giant Hogweed is also an invasive species which is an ecological threat to the environment. 

As a result of it being a fast-spreading plant, it can crowd out native plants as well as destabilise riverbanks, which can increase erosion and the risk of flooding.

What should I do if I spot Giant Hogweed? 

Firstly, DO NOT touch the plant and make sure to keep children and pets away from it.

Giant Hogweed can cause severe burns and even brief contact, followed by sun exposure, can pose a serious risk. 

“Any sightings should be reported via the INNS Mapper so that the plant can be professionally controlled.

What should I do if I accidentally come into contact with Giant Hogweed? 

Make sure to wash the area thoroughly and seek medical attention. It’s also best to keep the area covered and out of the sunlight to avoid worsening burns and blisters.” 

Currently, the team from Riverlution and the River Stewardship Company are treating all of the main rivers and tributaries within the catchment area, including the Don, Sheaf, Porter, Riverlin, Loxley and Rother systems. This follows an extensive set of surveys, which were carried out earlier in the year. 

Including our work with invasive species like Giant Hogweed, through the collaboration between Riverlution and the River Stewardship Company, the partnership has delivered over £1.2 million in social value during 2024/25 and has focused on habitat improvement, flood defence, ecological restoration, and hands-on community training and apprenticeships.