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

Experts have warned the plant can result in anything from blisters to long-term scars

Some of Sheffield's rivers are home to a highly hazardous plant with toxic sap - which can cause severe burns, blisters and in worst cases long-term scarring.

Giant hogweed is not native to the UK. It originates from the Caucasus Mountains and Central Asia, but it naturalised in the wild in the 19th century. Not only is it now classed as an invasive species - it is also considered to be very fast growing and toxic to the touch.

The sap of Giant Hogweed contains furocoumarin - making skin extremely sensitive to sunlight (phytophotodermatitis). If the sap gets onto your skin and it's then exposed to the sun, your skin can blister badly. Blistering can then recur over months and even years. This is known as phytotoxicity.

If you happen to come in contact with the plant, it is important to remember a few key steps: Firstly, do not touch the plant and make sure to keep children and pets away. If you do happen to come into contact with the plant, it is important that you 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.

As well as being toxic, it's non-native nature means that it impacts the environment around it - In short, Giant Hogweed is not good news.

With this in mind, many environmentalists are trying to not only raise awareness of the plants toxic nature, but get rid of the species entirely. The River Stewardship Company, Riverlution have been managing Giant Hogweed along Sheffield’s five rivers for around 15 years, thanks to support from local businesses and agencies.

Geoffrey Guy, Managing Director at Riverlution, explained that locals can help reduce the growth of the invasive species in the future: "Any sightings should be reported via the INNS Mapper so that the plant can be professionally controlled. 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."

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 their 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.

Yorkshire Live