House Plants Can Cause Allergic Reactions


   Hamburg - When people come down with a runny nose and itchy eyes in their homes, they often think the cause is an allergy. The usual suspects are dust mites and any pets in the home. They should, however, also consider their house plants, although it is difficult to definitively prove they are the cause.

   Initially, tests must be conducted to rule out dust mites. The search for the cause then moves on, using important tips taken from the understanding of known allergies. Apart from that, patients and their dermatologist or family doctor should discuss whether anything in the home has changed. That includes any newly-acquired house plants.

   "Basically, any house plant can set off an allergy," said Stefan Gentzen, director of the German garden retailers' association in Berlin. "At the time of the sale customers generally don't know that they will have an allergic reaction to the plant."

   There are, however, plants that are known to cause allergic reactions. If one of these plants is in the home, it should be included in the test.

   The best known example is the ficus, (Ficus benjamina), also known as weeping fig or Benjamin's fig, but that doesn't mean that when it comes to allergies that the plant is more dangerous that other house plants.

   "The ficus is found in almost every office building and in many private homes. That's why it is known for touching off allergies," Gentzen said. The plant's allergens come from the milky sap on the surface of the leaves.

   "It attaches itself to dust particles and that's how it spreads throughout the room. This process can take a long time," said Anja Schwalfenberg, patient adviser at the German allergy and asthma association in Moenchengladbach.

   People with latex allergies are the most likely to react to this allergen. The ficus' allergens are very similar to the latex protein.

   "The types of immediate reactions are running nose, itchy eyes and respiratory problems similar to asthma. Hours later eczema could develop," Schwalfenberg said. People who have a latex allergy should therefore avoid the ficus. The same applies for other plants in the mulberry family such as rubber tree plants (Ficus elastica) and plants in the Euphorbia family such as the poinsettia (Euphorbia pulcherrima).

   Less well-known is the allergic potential of plants in the Asteraceae family such as chrysanthemums and daisies. This is particularly important for people who garden.

   "Their allergens are dispersed in an area through pollen and can cause sniffles or asthmas," said Thomas Fuchs, president of the professional association for Germany allergists. The most vulnerable people are those with a mugwart allergy because there can be a cross sensitivity.

   Many early blooming plants also harbour dangers, however, they are more critical for florists than gardeners.

   "Frequent contact with tulip bulbs or primroses can cause contact allergy on the hands," said Fuchs. One of the most common is a particular type of primrose (Primula abconica). Its allergen sits on the underside of the leaves, and on the top surface of the leaves if the plant is wilting. There is only one thing that can help: avoid touching the plant.

   Apart from the plant, the soil also is a risk factor for allergies.

   "Plant soil as well as hydroponics contain mould spores, which find ideal conditions in the pot and distribute themselves through the air," said Schwalfenberg. It's not easy to avoid this problem. If there is mould in the soil, the plant can be transplanted. "But the problem isn't necessarily solved. The organic material contains spores, so mould can start forming again," said Gentzen.

   The incidence, however, can be limited.

   "The humidity is too high in most rooms. This makes it very important to air out the room regularly," said Fuchs. "In addition, house plants should get only as much water as they actually need."

   People who know that they are allergic to mould spores or to a specific plant should keep away from that plant, Fuchs advised. "In such cases the affected person should remove the plant from the apartment or at least from the bedroom."