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Hogweed Dermatitis
Figure 2.

Differential Diagnosis

  • Arthropod bites or stings
  • Hogweed dermatitis
  • Solar urticaria
  • Sunburn


The correct diagnosis in this case is hogweed dermatitis. Exposure to the giant hogweed plant (Heracleum mantegazzianum) can cause phytophotodermatitis, especially in sunlit environments. A toxic psoralen present in the sap, furocoumarin, is highly lipid-soluble and penetrates into the epidermis. Absorption of ultraviolet A by the psoralens leads to nucleic acid damage and formation of free radicals. Subsequent cell death leads to the quick formation of painful blisters.

What to Look For

  • Preceding the skin lesions, the patient may experience a burning sensation. This is followed by erythema, edema, and vesicle formation within 24 hours of contact with the hogweed sap
  • If severe, patients experience headaches and generalized fatigue; they may also complain of feeling hot
  • Contact of the sap with the eyes can cause temporary or even permanent blindness
  • Symptoms usually develop within 18-48 hours following contact with the sap and sunlight exposure, and symptoms may continue for a month
  • The plant is large with a hollow stem, and children may be inclined to use it as a play telescope or sword

Pearls for Urgent Care Management

  • Ensure the area has been cleaned with soap and water to remove all sap
  • Initial treatment is with a topical steroid
  • Use over-the-counter non-steroidal anti-inflammatories for pain management
  • If the patient has severe wounds, demonstrating 2nd or 3rd degree burns, contact a burn center

Read More

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