Many gardeners and hikers have endured some form of dermatitis after contacting certain plant species. Skin irritation, itching, rashes, blisters, swelling, and other symptoms can be caused by many parts of the plant, including sap, plant “hairs,” or thorns (thorn punctures can also introduce infection-causing bacteria or fungi).
Dermatitis rashes may be painful and can be quite serious. In some cases, sunlight may exacerbate the rashes.
Types of dermatitis caused by plants
Three types of plant-induced dermatitis include:
- Irritant contact dermatitis – chemical reaction on the skin after contacting the plant, which affects many people
- Phytophotodermatitis – secondary sun-enhanced reaction after contact with the plant
- Allergic contact dermatitis – occurs only in susceptible individuals
1. Irritant contact dermatitis
There is an extensive list of plants that cause irritant contact dermatitis, including
Flowering bulbs – gladiolus, tulip, daffodil, alstroemeria, etc.
- Ivy (Hedera spp.)
- Black walnut (Juglans nigra)
- Eucalyptus, blue gum (Eucalyptus spp.)
- Tomato plants
- Stinging nettle hairs (Urtica spp.)
- etc. . .
Sometimes the dermatitis is caused by irritant sap or latex in the plant, such as occurs with:
Agave, century plant (Agave spp.)
- Spurge, poinsettia (Euphorbiaceae family)
- Ranunculaceae family – Buttercup, anemone, ranunculus, pasque flower, etc.
- Frangipani, etc. (Apocynaceae family)
- Daphne (Daphne mezereum)
2. Phytophotodermatitis (“phyto-photo-dermatitis”)
Some plants sensitize the skin to UV light. Subsequent exposure to sunlight can cause a mild “sunburn,” or even severe secondary burns. Hyperpigmentation may also result after contact with these plants, which can persist for months. Examples of plants causing phytophotodermatitis:
- Figs (Ficus spp. – rubber plant, fig tree, etc.)
- Citrus (lime juice, etc.)
- Queen Anne’s lace, and carrot plants (Daucus carota)
Phytophotodermatitis is a common problem for susceptible gardeners who work outdoors and work repeatedly with offending plants — such as pruning fig plants.
3. Allergic contact dermatitis
Allergic contact dermatitis affects only certain individuals, and can be caused by many plants. Most people are familiar with the dermatitis caused by plants in the Anacardiaceae family:
- Poison oak (Toxicodendron diversiloba) Wild plant
- Poison ivy (Toxicodendron radicans) Wild plant
- Poison sumac (Toxicodendron vernix) Wild plant
- Sumacs (Rhus spp.) Ornamental
- Pepper tree (Schinus spp.) Ornamental
- Smoke tree (Cotinus coggygria) Ornamental
- Cashew (Anacardium occidentale) Food
- Mango (Mangifera indica) Food
If you know you are allergic to any of these plants, you should avoid exposure to them.
Prevention and treatment
Please do not use this information as medical recommendations. In case of a serious reaction to any plant, always seek immediate medical help from a professional or contact a poison control center (U.S. Poison Control Center: telephone 800-222-1222).
Preventing exposure to dermatitis-causing plants is always the best bet. When gardening or hiking, wear protective clothing, and launder the clothing after exposure. If skin comes in contact with plants that can cause dermatitis, wash the skin as soon as possible with cool water and mild soap.
Gardeners and landscape workers should be aware of plants that are notorious for causing dermatitis, and should wear protective clothing, including gloves, long sleeves, long pants, closed shoes, and sun-protective clothing (for plants that cause phytophotodermatitis).
I am not a medical professional, so I won’t give medical advice, but don’t hesitate to get professional medical help when dermatitis occurs — reactions can be severe in some people, so medical help may be necessary.
Plant lists / Websites
I maintain a website — Safe and Poisonous Garden Plants — with lists of toxic ornamental plants (including those causing dermatitis). Plants are listed by both common name and scientific name: http://ucanr.edu/sites/poisonous_safe_plants/
- Safe and Poisonous Garden Plants http://ucanr.edu/sites/poisonous_safe_plants/
- Poisonous Plants; Centers for Disease Control http://www.cdc.gov/niosh/topics/plants/
- Poison oak: More than just scratching the surface http://waynesword.palomar.edu/ww0802.htm