top of page

Safety Alert: Giant Hogweed and Wild Parsnip


At The Shaw Group, we are continuously looking for hazards that could harm us, there are a couple of plants that can be found in New Brunswick and Nova Scotia that can cause serious burns. The purpose of this Hazard Alert is to inform everyone of this potential hazard so we can continue to drive our safety culture forward through hazard recognition.

Giant Hogweed/ Wild Parsnip Burns: Symptoms, Treatment, and How to Avoid

Wild parsnip (Pastinaca sativa) is a tall plant with yellow flowers. The roots are edible. Giant hogweed (Heracleum mantegazzianum) can grow up to 14 feet tall and has white, upwards-facing flowers that in summer, arranged in umbels that can be as large as 2ft (60cm) across. It is part of the carrot family. Both plant's sap can result in burns (phytophotodermatitis).

The burns are a reaction between the plant’s sap and your skin. The reaction is triggered by sunlight. It isn’t an immune or allergic response, but rather a sun-sensitive skin reaction due to the furanocoumarin in the plant. Furanocoumarin makes skin extra sensitive to UV light.

If your skin has come in contact with sap from either of these plants, immediately cover the affected area. Your goal is to shield your skin from sunlight to prevent a reaction.

Once inside and out of the sun, wash the contact area with mild soap and warm water. Even after washing, the area might be sensitive for about 8 hours and must be kept out of the sun and away from UV light for that period.

Symptoms of phytophotodermatitis burns

About 24 hours after getting the sap on your skin and being exposed to sunlight, you’ll begin to experience symptoms. Symptoms start with an intense local burning sensation, followed by a red rash. Over the next couple of days, the rash may get worse — sometimes with severe blistering (see below).

Some people may not recall any redness or blistering. Instead, you may see irregular patches on the skin, sometimes as linear streaks, a random cluster of small spots, or even fingerprint-sized spots.

After about 3 days, the symptoms start to get better. Eventually, like after a bad sunburn, the burned skin cells die and flake off.

As symptoms improve, the rash may appear lighter or darker. Discoloration and sensitivity to sunlight in the affected areas can remain for up to 2 years.

How to treat phytophotodermatitis burns

The burns will resolve on their own with time. It’s important to keep the affected area from being exposed to sunlight to avoid further burning and prevent further discoloration. Sunscreen is essential to prevent dark spots from darkening in the sun.

If contact with wild parsnip or giant hogweed sap followed by exposure to sunlight causes a burn and blisters, you can try ice packs for pain relief.

If needed, try an over-the-counter (OTC) hydrocortisone cream to help soothe the inflammation. You might also consider using ibuprofen or acetaminophen for pain relief.

If the burn and blistering are severe, see a doctor. They may recommend a systemic or more potent prescription topical steroid to help relieve your discomfort.

Your skin will typically heal without an infection. Get immediate medical care if you see the signs of infection, such as:

  • fever of 100.4°F (38°C) or higher

  • increasing swelling or redness

  • pus coming from the affected area

To avoid, or at least reduce the risk of exposure to wild parsnip or hogweed sap, wear full-coverage shoes, long pants, and long-sleeved shirts when involved in outdoor activities. Do not attempt to cut these down or disturb them without proper PPE and training or leave it to a professional landscaper with experience to do so safely.


bottom of page