Allergy to plants

Many plants cause allergic reactions (eczema) if they are touched. In Denmark the most important plants in this group are members of the Primula family (in particular the species obconica) and members of the Asteraceae, or daisy, family.

 

The daisy family

The daisy family is one of the world’s largest plant families. It includes not only many familiar garden flowers, such as chrysanthemums, asters, sunflowers, marigolds and marguerites, but also weeds, such as dandelions, daisies, camomile and tansy. Lettuce, estragon and artichokes are among the edible plants of this family. Many of the plants from the daisy family have traditionally been used for medicinal purposes. In particular, camomile, arnica and marigolds are widely used in natural medicines and cosmetics.

What are the symptoms of plant allergy?

Typically, a red, itchy rash develops, sometimes with small blisters, on the area that has been in contact with the plant, usually the hands and arms and the face and neck. Rashes on the face and neck are caused by airborne allergens released by the plant when it is touched landing on exposed areas of the body, and by the plant allergens ‘evaporating’. The symptoms are more common in the summer months, when people are most often outdoors and frequently exposed to plants.

Who gets plant allergy?

If plant allergy develops it is usually only after prolonged exposure to a plant. Gardeners and florists are therefore particularly susceptible. People working with food preparation are also susceptible if they frequently handle vegetables from the daisy family. In Denmark, many cases are seen in people who have gardening as a hobby and who have long tended their gardens with chrysanthemums, marguerites and other members of the daisy family. Pet owners are also susceptible if they frequently pick dandelions and lettuce leaves, for example, for their rabbits and guinea pigs.

The chrysanthemum–a member of
the Asteraceae, or daisy, family

How is it diagnosed?

Allergy to plants is diagnosed using a patch test, also called a plaster test. An adhesive strip with small foil pockets containing the plant allergens or plant extracts to be tested is attached to the patient’s back where it remains for 48 hours. When the plaster is removed any eczema-like skin reaction under where the plaster was will indicate an allergy. To have a patch test, you must be referred by your general practitioner to a dermatology clinic or to the dermatology department of a hospital.

In the general population, it is unknown how often plant allergy occurs. In eczema patients tested in a hospital dermatology department, approximately 1% had Primula allergy and 1%–3% had Asteraceae (daisy family) allergy. 

Treatment

 

Severe cases of plant allergy eczema can be treated with adrenal cortex hormone cream. This must be prescribed by your doctor or a dermatologist. Avoid handling the plants that cause your allergy. If you have Primula allergy, avoiding the plants should not be difficult; however, because of the many plants in the daisy family, avoiding the allergenic plants might pose a problem. With allergy caused by the daisy family, a preventative treatment is often prescribed during the summer months. This is in tablet form and it works by desensitizing the skin to the plant allergens.

 

What can you do yourself?

Plant allergens are on the plant itself and are released when the plant is touched. The allergens are also in the plant juice, which can come into contact with the skin if the plant is picked or damaged. Therefore it is a good idea to always use gloves whenever you handle plants, particularly if you are planting up, pruning or removing dead heads and leaves. Avoid all direct skin contact with the plant; use scissors to remove dead heads etc. Be especially careful if you already have eczema on your hands, as you will be more vulnerable to other allergies.
If you develop work-related plant allergy, you are eligible for compensation. Therefore you should be examined so that the allergy can be registered with the Danish Working Environment Authority and the National Board of Industrial Injuries.

About Primula allergy

Some new types of primula have been developed that are not allergenic, for example, the type ‘Touch me’.

About Asteraceae allergy

If you have Asteraceae allergy, you should not have any daisy-family plants on window sills, in window boxes and in flower pots or beds. Using gloves will not sufficiently protect you from these plants’ allergens, as they are also airborne. You can find out more about which houseplants, bedding plants, and shrubs belong to the daisy family in the books listed below.