Burns, sore spots, and huge eerie-shaped blisters are a common reason for seeking medical attention after contact with hogweed. This plant is widespread, its tall (sometimes more than two meters) stems with wide leaves and a large umbrella of flowers attract with their exoticism. As a result, after close contact with hogweed (many people want to touch it, pluck it, take pictures in its thickets, walk between plants), patients get photodermatitis and rush to a dermatologist for help.
Why there are severe skin lesions from contact with hogweed
The frightening appearance of lesions after contact with hogweed is due to the fact that the leaves of this plant contain a lot of essential oil, which includes photosensitizing chemical elements – furanocoumarins. When these substances, upon contact with the plant, are on the skin – at first nothing happens, but as soon as the sun's rays of a certain length fall on the skin patches where the furanocoumarins remain, these substances change their chemical structure under the action of the sun and release energy in the form of heat. The result is a skin lesion that is closer to a chemical burn than to dermatitis. The degree of skin damage is higher, the stronger was the insolation. The energy released by furanocoumarins destroys cells, causes processes in the skin that lead to hyperemia, edema and the appearance of blisters. Later, hyperpigmentation occurs on the affected area of \u200b\u200bthe skin – as a kind of protection that the body puts up against excessive insolation.
Clinical picture of photodermatitis caused by hogweed
Photodermatitis caused by contact with plants and subsequent insolation has been described in relation to various herbs and flowers, in foreign literature it even has the name "combiner dermatitis". Patients of a dermatologist usually complain of severe burning in the affected area, the appearance of hyperemia and blisters, resembling a severe burn.
Signs of photodermatitis after contact with hogweed do not appear immediately, but after 1-2 days – at first it is erythema, then rather quickly there are blisters that turn into blisters – from large to gigantic. Most often, patients complain not of itching, but of a burning sensation in the affected area. The patient's temperature may rise to febrile values, but this is a short-term phenomenon.
Rashes appear at once, and sometimes they line up with a characteristic pattern – along the line of skin contact with the plant; they are strictly limited to the site of such contact and do not extend to other areas of the body, but only where the plant touched the skin, and then the sunlight hit.
The blisters that have arisen on the affected areas are usually transparent, their contents do not suppurate. After 2-4 days, the blisters open on their own, erosions form in their place, which persist for 1-2 weeks, and then turn into erythema. It all ends with the development of hyperpigmentation, which can persist for about 2 months, and then the skin structure is usually completely restored.
Photodermatitis provoked by cow parsnip is a purely phototoxic reaction, which does not depend on the patient's gender, age, or the state of his immune system. However, it is most severe in fair-skinned people.
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Treatment of photodermatitis caused by contact with hogweed
The tactics of treating photodermatitis provoked by contact with plants, in particular with hogweed, causes serious discussion and requires further research. So, some experts recommend washing off the irritant with water, while others indicate that this increases the area of contact with the furanocoumarins contained in hogweed, which means that the amount of skin damage increases.
Early use of local steroid preparations has shown to be ineffective, since in this type of photodermatitis there is no classical phase of inflammation, but in the phase of erosion formation, such therapy is justified – drugs in the form of an emulsion work effectively. The use of systemic steroids does not affect either the duration of the disease or its course. Topical corticosteroids for photodermatitis can relieve some pain and burning, and reduce the intensity of hyperpigmentation.
NSAIDs are used as symptomatic therapy, which in the first two days after the onset of the disease help to reduce pain and slightly limit the spread of inflammation. You can reduce the intensity of burning with the help of antihistamines that have a sedative effect.
In the bullous phase of photodermatitis caused by cow parsnip, the use of any local medicines provokes an early opening of the blisters and slows down the process of restoring the skin. In case of photodermatitis, the blisters should not be opened, because this can form secondary scar tissue, and also increases the risk of infection.
The patient should be aware that even after the end of treatment, he should avoid sun exposure and use sunscreens to prevent possible pigmentation in areas of skin affected by cow parsnip.
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