The Content Of The Article:
- What is phototoxic?
- What happens in a phototoxic reaction?
- Meadow grass dermatitis and Co.
- What to do in meadow grass dermatitis?
- The most important phototoxic plants
Most gardeners have seen the symptoms before: In the middle of summer gardening suddenly red spots appear on the hands or forearms. They itch and burn and often get worse before they heal. An allergy is not known and the parsley just harvested is not toxic. Where does the sudden skin reaction come from? The answer: some plants are phototoxic!
Reactions of the skin, which occur in connection with sunshine, ie especially on hot summer days or on beach holidays, are usually summarized under the term "sun allergy" (technical term: Lichtdermatose). Exposure to intense sunlight on the skin causes itchy and burning red patches, puffiness and small blisters. Particularly affected are the trunk and the arms. Although about 20 percent of the fair-skinned population are affected by the so-called polymorphic photodermatosis, the causes are still not fully understood. However, if the skin reaction occurs after gardening or a walk in the woods in shorts and open shoes, there is probably another phenomenon behind it: phototoxic plants.
If you walk barefoot in the woods, you have to be careful where you are going
What is phototoxic?
Phototoxic refers to a chemical reaction in which certain non-toxic or only slightly toxic plant substances are converted into toxic substances in combination with solar radiation (photo = light, toxic = toxic). This causes painful skin symptoms such as itching, burning and rashes on the affected areas. A phototoxic reaction is not an allergy or photodermatosis, but a combination of plant ingredients and UV radiation that is completely independent of the person concerned. With a scientific name, the skin reaction resulting from a phototoxic effect is called "phytophotodermatitis" (dermatitis = skin disease).
What happens in a phototoxic reaction?
Many garden plants contain chemical substances that are not or only slightly toxic on their own. For example, if you get secretions on the skin when cutting plants, nothing happens at first. But keeping the affected part of the body in the sun and exposing it to such high-dose UVA and UVB radiation changes the chemical composition of the ingredients. Depending on the active ingredient, either the activation of new chemical processes by heating or the release of other chemical compounds that have a toxic effect on the skin then occur. The result is a few hours later redness and swelling of the skin to dandruff through dehydration in conjunction with itching and burning. In bad cases, a phototoxic reaction can lead to blistering - similar to what we know from blistering. Around the rash is often observed a darkening of the skin such as strong tan (hyperpigmentation). Since the appropriate body part for the development of a Phytophotodermatitis must first be exposed to the plant secretion and then strong sun, usually hands, arms, feet and legs are affected, rarely face and head or upper body.
The redness and blistering resembles a fierce sunburn
Meadow grass dermatitis and Co.
In the vernacular, the phytophotodermatitis is also called meadow grass dermatitis. It is mainly caused by the furocoumarins contained in many plants, more rarely by the hypericin contained in St. John's Wort. Upon contact with the sap and subsequent exposure to the sun, a strong rash develops with a delay of redness and blistering on the skin, similar to a burn. This reaction is so strong that it has a carcinogenic effect and should therefore be avoided if possible! Since furocoumarins are also found in many citrus plants, bartenders at sunny holiday resorts also speak of "Margarita Burn". Attention: Increased photosensitivity of the skin and phototoxic reactions can also be triggered by medications (for example St. John's wort preparations), perfume oils and skin creams. Please read the packing instructions!
Even after cutting parsley, a rash may occur
What to do in meadow grass dermatitis?
If you notice any onset of dermatitis after you have been in contact with plants (for example, during a walk), wash all potentially affected areas immediately and avoid further exposure to the sun in the days to come (for example, through long trousers and stockings). Meadow grass dermatitis is a harmless skin reaction, provided it is restricted to smaller areas. If larger areas of skin or small children are affected, in case of severe pain or blistering, it is necessary to visit the dermatologist. The procedure is similar to a sunburn treatment.Cooling pads and mild creams moisturize and soothe the itch. In no case scratch! Important to know: The skin reaction does not occur immediately, but only after several hours. The peak of the rash is usually reached after two to three days, so it gets worse before the skin irritation heals. After about two weeks - with strong reactions also longer - the rash disappears by itself. The tanning of the skin usually develops afterwards and can persist for months.
Citrus plants contain phototoxic substances
The most important phototoxic plants
The main plants that cause skin reactions in combination with sunlight include many umbelliferae such as bear's claw, meadow chervil and angelica (Angelika), but also Diptam (Dictamnus albus) and rue. Particularly common triggers are citrus fruits such as lemon, lime, grapefruit and bergamot, when the fruits are squeezed out with the bare hands. Wash yourself in the summer after harvesting the fruit and process your hands! Be careful when working with parsley, parsnips, coriander, carrots and celery. Buckwheat also causes itching and rashes due to the fagopyrin it contains (so-called buckwheat disease). Gardening gloves, closed shoes and long-sleeved clothing protect the skin.