Some plants can cause itchy rashes when touched. Poison ivy may come to mind, but many common garden plants can also be skin irritants for sensitive people. Sometimes it is just a certain part of the plant that irritates, like the sap of Euphorbia or the roots of hyacinth. Although, for some extremely sensitive people, any part of a plant they are affected by can cause irritation.
Types of Plant Irritation
There are three general ways plants become skin irritants:
- Chemical irritation: In the common case of poison ivy, the irritating chemical compound, urushiol, is absorbed right into the skin. Some people remain unaffected while others can have an extreme reaction. Unfortunately, just because you've been immune to urushiol in the past does not mean you will never be affected by it, so everyone should use caution around poison ivy plants. Irritating chemicals also can be transmitted to your skin in the winter when a plant looks dormant.
- Light sensitivity: Some plants are irritants only when they are exposed to sunlight, which also happens to be when most people are in their gardens. This is the case for plants in the carrot family, like parsnips and Queen Anne's Lace.
- Mechanical injury: Plants such as nettles have sharp edges or thorns that can break the skin and introduce their toxins through the wound.
What to Do if Exposed to One of the Plants
You may notice your skin becoming itchy, even before any visible irritation appears. At the first sign of irritation, wash the area with soap and water and gently blot dry. Avoid touching your eyes or mouth area. An over-the-counter cream may be all you need for relief, but call your doctor if the rash worsens or if you develop blisters.
Here are 36 plants of varying toxicity, and the health problems and conditions they cause.
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Bishop's Weed (Aegopodium podagraria)
Bishop's weed, also known as goutweed, is a popular ground cover, but it can cause the skin to develop a sensitivity to ultraviolet light, causing itching, rashes, or blisters.
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The scratchy hairs of black-eyed Susan can cause mild skin irritation that usually subsides when the area is washed with soap and water.
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All parts of blanket flower contain sesquiterpene lactones, a chemical compound that is common in many plants and can cause skin irritation if you come in contact with the sap.Continue to 5 of 36 below.
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Bleeding heart and its relative, Dutchman's breeches (or britches), contain alkaloid toxins similar to those contained in poppies. All parts of the plant are poisonous if ingested, and they can cause skin irritation in some people.
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Skin irritations from carrots develop more commonly after they are eaten, rather than through skin contact. In people with carrot allergies, histamine, and other chemicals can be released into the bloodstream, resulting in swelling and an itchy, red rash as well as a runny nose. This usually dissipates shortly after eating but can be more severe in some cases.
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Dill can cause an itchy irritation if the juice comes in contact with skin. However, this is usually minor. Dill can also cause photosensitivity or acute sensitivity to sunlight on the skin.Continue to 9 of 36 below.
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The leaves and stems of elephant ears contain calcium oxalate crystals, small, sharp formations that can cause painful swelling if they come in contact with the skin or mouth. Several houseplants also contain oxalate crystals, including dumb cane (Dieffenbachia), mother-in-law's tongue (Sansevieria trifasciata), Philodendron, and the peace lily (Spathiphyllum).
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English ivy contains falcarinol, a fatty alcohol also found in carrots, which can be an allergen to some people if they come in contact with the sap. Just touching the leaves should not result in the blistering rash; however, most people should use caution when clearing a large patch of English ivy.
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Fennel is sometimes used as an insect repellent and can cause contact dermatitis in sensitive people. Washing the area with soap and water should alleviate the symptoms.
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Allergic contact dermatitis can occur in people who have previously been sensitized by fleabane and can take up to two days before showing symptoms.Continue to 13 of 36 below.
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Gas Plant (Dictamnus albus)
The gas plant is one of a handful of plants that cause what is called photodermatitis. A chemical in the plant reacts to UVA light and causes blistering that can take a few hours to develop. The skin can remain discolored for months after the blisters fade.
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Hops can cause contact dermatitis from handling the oil and also from contact with the scratchy hairs on the stems and hops. People who harvest hops occupationally can become extremely sensitive and experience a much stronger reaction, such as asthma, but the home gardener is rarely affected this way.
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About 6 percent of the hyacinth bulb is composed of calcium oxalate crystals. Although tiny, these crystals are sharp and can irritate skin on contact. They can also become airborne and cause rashes on other areas of skin.
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Iris rhizomes contain a substance called irisin, which can be toxic if ingested and can also cause a mild skin rash on contact.Continue to 17 of 36 below.
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Lady's slipper (Cypripedium)
The stems and leaves of lady's slipper are covered in coarse hairs that can cause skin rashes when handled. Photosensitivity can also occur.
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May Apple (Podophyllum peltatum)
Although may apple fruits are edible when fully ripe, the rootstock can cause skin rashes in some people, as can the juices from the broken leaves and stems.
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Mugwort allergies can be common in people who are allergic to other plants, especially those in the chrysanthemum family. One of the common reactions is contact dermatitis.
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Parsnips can cause phytophotodermatitis, a blistering rash that is the result of exposure to the plant's sap while out in sunlight. It can occur with any member of the carrot family and is generally worse with wild cow parsnip than with cultivated parsnip.Continue to 21 of 36 below.
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Poinsettia plants have gotten the undeserved reputation of being extremely poisonous. They are not as toxic when ingested as is commonly believed, but the milky sap can cause contact dermatitis.
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Poison Hemlock (Conium maculatum)
Poison hemlock is in the carrot family and looks like a giant parsley plant. The plants can reach 7 feet tall, and the stems are marked with purple blotches. Poison hemlock can be fatal if ingested and also has oils that can be absorbed through the skin.
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Most people are aware that poison ivy can cause an itchy rash or worse. Be very careful removing it, and do not burn it, or you could breathe in the oils. Poison ivy can be either a vine or a low-growing shrub.
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Poison oak, like poison ivy, has "leaves of three," so let it be. However, the leaves of poison oak are lobed, like an oak tree leaf, and have fuzzy hairs on them. Poison oak causes a rash similar to poison ivy. The plant grows as a shrub.Continue to 25 of 36 below.
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Not all sumacs are poisonous and cause an itchy rash. Poison sumac has hairless, berrylike drupes that start off green and ripen to a grayish-white. Non-poison sumacs tend to have fuzzy, red seed clusters.
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Allergens in the hairs along the stems and leaves of primrose plants can cause contact dermatitis that can sometimes be quite severe.
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Queen Anne's Lace (Daucus carota)
Queen Anne's lace, or wild carrot, is another plant that can cause phytophotodermatitis, a blistering rash that occurs when the sap comes in contact with the skin in sunlight. Allergies to Queen Anne's lace are not as common as with its relative wild parsnip, but more people come in contact with Queen Anne's lace.
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Rue contains the same furocoumarin chemicals as gas plant and can cause a photochemical reaction resulting in blistering and skin discoloration.Continue to 29 of 36 below.
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Helenium plants contain a substance known as sesquiterpene lactone, which can cause a skin rash in some people and, if ingested, is extremely toxic to people, pets, livestock, and fish.
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A milky sap that exudes from Euphorbias causes skin irritation. This includes ornamental spurges and weeds, such as cow parsnip. Exposure to sunlight can make the irritation even worse. Giant hogweed rashes can be so severe that they leave scars. Euphorbia sap is also toxic if ingested and is considered a carcinogen.
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Stinging nettle plants have small hairs that puncture the skin and exude a combination of histamine, serotonin, acetylcholine, and formic acid, which results in welts and very itchy, stinging skin. Formic acid is one of the irritants in bee stings, and the reaction can be similar to a sting.
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Contact with tansy plants can cause a dry, itchy rash due to the sesquiterpene lactones in the plant parts.Continue to 33 of 36 below.
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Rashes from handling tulip bulbs are so common they have their own name: "tulip bulb dermatitis" or "tulip itch." The reaction can be anything from red, itchy skin to blistering.
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Wild Ginger (Asarum)
Although wild ginger is often used as a medicinal herb, the oils from the leaves can cause contact dermatitis in some people.
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Yarrow is one of many plants that contain sesquiterpene lactone, which can cause contact dermatitis, hives, and photosensitivity.