Identifying and Avoiding Giant Hogweed

Laura Mitchell's picture
By Laura Mitchell on July 25, 2018

Giant hogweed has made its way to Virginia, and with it comes fear of exposure. Giant hogweed sap is toxic to humans, causing rashes and burns on contact. While it has only been found in a few isolated locations, experts recommend that residents learn to recognize it in order to prevent exposure.

Carilion Clinic Emergency Medicine physician Stephanie Lareau, M.D., directs our Wilderness Medicine fellowship. We spoke with Dr. Lareau about the dangers giant hogweed presents, and what to do if you are exposed to it.
Risks of Giant Hogweed

Hogweed contains phytotoxins, or defensive chemical compounds, that are activated by ultraviolet light and damage human DNA, causing significant burns and long-lasting scars. Exposure to giant hogweed can also result in ocular (eye) burns, which can lead to blindness.
The harm hogweed can cause depends on the amount of exposure to the plant combined with subsequent exposure to sun.
According to researchers at Virginia Tech, giant hogweed is still rare in Virginia and can easily be mistaken for the more common cow parsnip, angelica or even Queen Anne’s lace. While all have umbrella-shaped clusters of white flowers, the more dangerous giant hogweed has a blotchy red stem and can grow to 15 feet tall with leaves as large as five feet across.

Don't get close to inspect for differences, though. Cow parsnip can also cause a mild skin rash, so experts recommend avoiding both plants altogether, and wearing gloves and protective clothing when doing yard or trail work.

Treatment for Exposure

Early recognition and treatment are very important in preventing potentially life-threatening reactions. If you think you’ve come into contact with hogweed, Dr. Lareau recommends that you immediately get out of the sun and wash the area with large quantities of cold water to attempt remove the sap from your skin.

You can also use a mild soap if you have it. If you must be in the sun, use sunscreen. If you see any evidence of skin changes, such as redness or blistering, seek medical care immediately.

Treatment for giant hogweed exposure depends on the severity of the exposure and the skin's response to it. According to Dr. Lareau, minor skin irritation may be treated with topical steroid cream and oral non-steroidal anti-inflammatory drugs, whereas more extensive burns may require surgical care in a burn center. 

What You Can Do

Because hogweed is a relatively new occurrence in Virginia, many clinicians may not be very familiar with it, so if you are exposed and seek treatment, try to provide as much information about exposure as you can, to help guide medical care.

If you suspect you have found giant hogweed at home or elsewhere, experts ask that you take photos of the leaf, stem and flower, and contact a Virginia Cooperative Extension agent or the Virginia Department of Agriculture and Consumer Services.