As the weather warms up, many of us are starting to spend more time outdoors with our families. Tending the garden, mowing the lawn, or just enjoying a walk in a local park can be a great way to get exercise, relieve stress, and spend time together as a family. Unfortunately, the warm weather brings with it many allergens that leave people sniffling, sneezing, and itching. Poisonous plants, namely poison ivy, oak, and sumac, are some of the summer’s biggest outdoor menaces. According to Dr. Kyle Kaltwasser of U.S. Dermatology Partners in Baytown and Clear Lake, Texas, “Many people react to poisonous plants, and even a minor exposure can be very uncomfortable. These reactions untreated can last days to weeks so treating the rash right away can help to minimize discomfort and get the skin back to normal faster.” In this blog, Dr. Kaltwasser will walk through how poisonous plants can impact skin health, ways to prevent skin irritation from poisonous plants, and good treatment options to soothe itch, pain, and discomfort after exposure.
How Poison Ivy, Oak & Sumac Affects the Skin
Poison ivy, oak, and sumac all contain a compound called urushiol oil that can cause a severe reaction if it comes into contact with the skin. Since the compound is the same in all three plants, if you become allergic to one of them then you are allergic to all three of them. We are not born with this allergy but the compound is so reactive to the skin that even with the first exposure people may develop a severe skin reaction. This reaction has to be learned by the body so the skin reaction following the first exposure to urushiol oil may be delayed for days up to three weeks. Once the body has learned the allergic reaction though, skin irritation begins as quickly as four hours up to four days after exposure. It is possible for a person’s allergy to urushiol to decrease as they get older but for most people, the reaction actually becomes stronger with each exposure.
This type of reaction is what we call allergic contact dermatitis in which the skin responds strongly to chemicals or compounds that come into contact with the skin. Once the skin comes into contact with compounds such as urushiol oil, a cascade of inflammatory reactions follow that ultimately lead to redness, swelling, and severe itching at the site of exposure. Often the reaction is so strong that the skin even blisters.
Contact dermatitis due to these plants is sometimes so severe that the reaction will last for weeks until it finally calms down. During this time the itching and discomfort can be unbearable. The inflammation in the skin can become so severe that the inflammatory response from the body can spill over into other areas of the skin that were not exposed to the plants. This is actually very common with severe exposure to urushiol and referred to dermatologists as an id reaction. As with the initial area of involvement, these areas will eventually remit with time. Medical treatment is targeted at reducing this inflammation which leads to a reduction in the symptoms of the skin and an accelerated time to recovery.
After the skin reaction resolves some people will notice either darker or lighter colored skin at the sites of reaction. This is what we call post-inflammatory pigment changes and it may take many weeks even up to 6 months in some individuals to completely resolve. Permanent changes to the skin are not typical with poison ivy, oak, or sumac exposure.
Symptoms of Allergic Reaction to Poison Ivy, Oak & Sumac
Each person’s response to poison ivy, oak, and sumac is a little different. As previously discussed, the exposure can be delayed up to 3 weeks with the first exposure or as early as 4 hours to 2 days with repeated exposure. While some people have mild symptoms that are tolerable, we frequently see patients with severe reactions that can continue to worsen for weeks. If you suspect you are developing skin reaction due to these plants you should consider discussing it with your dermatologist as soon as possible to hasten recovery and decrease your symptoms.
Some of the most common symptoms of an allergic response to poison ivy, oak, and sumac include the following:
- Itching is typically the first sign of exposure. The skin can be so itchy that it keeps you awake and makes you feel very uncomfortable. Do your utmost not to scratch the skin as this can increase the inflammation in the area leading to more itching later.
- After the itching starts, the skin will develop a red rash over the area that itches. The skin may or may not be swollen in these areas.
- In rare cases, people develop black spots or streaks in conjunction with or instead of a red rash.
- After a few days, the rash will blister and leak fluid.
- After the blisters dry up, the skin will scab over and begin to heal.
Identifying Poisonous Plants
In order to avoid unnecessary exposure to poisonous plants, you need to be able to identify them. For poison ivy and poison oak you can follow the old rule, “Leaves of three, let it be.” Both of these plants have three leaves or more specifically leaflets grouped together coming off a common stem from the branch though they can sometimes contain as many as 5 leaflets. Poison sumac, on the other hand, typically has 7 to 13 leaflets.
Though not generally recommended due to possible exposure, you can test plants to see if they contain urushiol. Perform the “black-spot test” by using a stone to thoroughly crush the plant, especially the leaf stalks between two folds of white paper. If present, the urushiol should turn dark brown within 10 minutes and black within 24 hours. Despite a negative test, if a plant looks suspicious then you should avoid it.
Remember that these plants contain urushiol year-round so you must always be watchful.
Poison ivy is one of the most prevalent poisonous plants across the U.S. It’s found in almost all U.S. states apart from Alaska, Hawaii, and parts of the west coast. Even though it’s called poison ivy, this plant may grow as a vine or a shrub. In most cases, you’ll find poison ivy growing near trees, shrubs, and along fence posts. A commonly shared rule for identifying poison ivy is “Leaves of three, let it be.” Each leaf of the poison ivy plant is made up of three smaller leaflets. The leaves are glossy, and the leaf edges may be smooth or textured. In the spring, leaves appear reddish. In the fall, leaves are yellow, orange, or red. In the summer months, leaves are green. Some varieties of poison ivy have flowers or berries growing on them.
The type of poison oak that grows will depend on the location across the U.S. In the south and east, poison oak is usually a low shrub. On the west coast, poison oak grows as long vines or tall clumps of plants. The leaves are fuzzy and green, again often found in clusters of three. Leaves have rounded tips, but they may be lobed or toothed around the edges. In some varieties, the plants grow yellow or white berries.
Found in the north and southeastern coast of the U.S and throughout the midwest, poison sumac usually looks like a tall shrub or short tree. The leaves cluster in clumps of seven to 13 smaller leaflets. Leaves appear orange in spring, they may be yellow, orange, or red in fall, and they are green in the summer months. Some varieties of poison sumac have small flowers or green or white fruit that grows in small clumps similar to grapes or berries.
Preventing Poison Ivy, Oak & Sumac Reactions
According to Dr. Kaltwasser, “The easiest way to prevent a rash from poisonous plants is to avoid contact with these plants. You should learn which plants grow in your area and how to correctly identify them.
Unfortunately, it isn’t always possible to correctly identify or avoid the plant but there are steps you can take to prevent getting the poison ivy rash. If you know you’re going to be spending time outside in an area where these plants grow such as hiking, camping, or hunting, you should plan ahead to protect yourself.” Whenever possible, keep skin covered with long sleeves, pants, and shoes. Extra layers are always best to prevent the oil from soaking through to the skin. If you are gardening or otherwise working with plants, you should wear gloves, specifically heavy-duty vinyl gloves as the oil can soak through rubber gloves.
There are products called ivy blockers you can apply to your skin to create a protective barrier that may help keep the urushiol oil from accessing and irritating skin. Organoclays such as bentonite, kalin, silicone, and quaternium-18 bentonite have been proven effective ingredients. Jewelweed (Impatients biflora) has been studied and found to be ineffective at blocking urushiol oil.
After being exposed to poisonous plants, you’ll need to carefully remove the oil from your clothing, outdoor items, and pets. Clean your clothing, including hats and gloves, right away. To remove the oil from your skin, start a hot shower and begin by rinsing with water only as using soap initially can spread the oil on your skin. Then take a washcloth with soap (more on specific soaps later) and wipe in a repetitive, high-pressure, single-direction under hot, running water. Both friction and heat help to remove the oil. You should wash your entire body for 3 rounds of about 3 minutes. Be careful not to scrub back and forth but only in one outward direction if possible. There are specially formulated body washes for poison ivy, oak, and sumac that have been shown to be the most effective, but using a dish soap such as Dial or oil-removing compounds such as Goop have also been proven to be successful. Regardless of the soap type, you should try to get the oil off of your skin within 1-2 hours of exposure if possible.
You should also wash gardening tools, hiking gear, camping equipment, outdoor furniture, and other items that might have been exposed to poisonous plant oils. Urushiol oil will remain in place on any surface until it is washed away completely, and until these items are cleaned, they can re-expose you, leading to a new rash. You can use dish soap and water to clean these items. If pets come in contact with poisonous plants, you should make sure to wash them regularly as urushiol oil can be transferred to your skin from pet fur.
If you do see these plants around your home, take care to remove them without allowing the plants to contact your skin. If you decide to remove the plant be sure to wear heavy-duty vinyl gloves as the allergen can pass through rubber gloves. After removing the plants, remove and wash all clothes and shower right away to minimize the risk of developing a reaction. NEVER burn the plant as the smoke can cause severe respiratory tract inflammation, dermatitis, and even temporary blindness. Eating the plant can also cause serious complications. It is best to either use a herbicide to kill the plant from afar, call a professional to come to remove the plant, or wear proper protective clothing and dispose of the plant into sealed garbage bags to be thrown away. After removing the plant, you should immediately wash all clothing/gloves and shower within 2 hours washing your skin as previously described regardless if you think you were exposed.
Treating Poison Ivy, Oak & Sumac
According to Dr. Kaltwasser, “If you do end up with a skin reaction to these poisonous plants despite your best preventive efforts, it is okay to let the skin reaction run its course if it is mild and tolerable. That being said, I personally recommend all of my patients seek treatment from a dermatologist if possible as there is no reason to suffer with the rash. For mild reactions, we typically will use only a topical medication but more severe reactions often necessitate oral therapy to get the rash under control. If you have been exposed to burning poison ivy, have ingested poison ivy, have a severe reaction on your face, excessive swelling of your skin/soft tissues, or other serious adverse effects, you need to contact your nearest urgent care or emergency room immediately.” To treat poison ivy at home, you should take the following steps:
- Don’t scratch the rash as it increases the risk for infection and makes the itching worse later
- Take short, lukewarm baths with colloidal oatmeal to soothe the itch. These baths can also help to dry out the blisters more quickly.
- Anti-itch creams like calamine lotion or hydrocortisone creams can be applied directly to the affected area to reduce the itch.
- Cold compresses can also be applied directly to the rash to relieve itch.
- Oral antihistamines (allergy pills) can also help relieve itch. Do not use topical Benadryl cream as it is not effective.
When to Visit U.S. Dermatology Partners for Poison Ivy, Oak, or Sumac Treatment
If you have a rash possibly from poison ivy, oak, or sumac that is not responding to at-home therapies or is moderate to severe, you should contact U.S. Dermatology Partners for an appointment. We can offer prescription oral and topical medications to soothe skin and help you recover completely in less time. We have resumed offering in-office appointments for non-emergency patients, and you can get started with a visit to our practice by completing our online request form. After completing the form, a member of our team will reach out to confirm your appointment date and time.
- Epstein WL. Topical Prevention of Poison Ivy/Oak Dermatitis. Arch Dermatol.1989;125(4):499-501.
- Guin JD. The black spot test for recognizing poison ivy and related species. JAAD.April 1980;2(4):332-3.
- Long D, Ballentine NH, Marks Jr JG. Treatment of poison ivy/oak allergic contact dermatitis with an extract of jewelweed. Amer J Contact Derm.Sept 1997;8(3):150-3.
- Marks JG, Fowler JF, Sherertz EF, Rietschel RL. Prevention of poison ivy and poison oak allergic contact dermatitis by quaternium-18 bentonite. JAAD.Aug 1995;22(2):212-16.
- McGovern TW. Dermatoses due to Plants. In: Bolognia JL, Jorizzo JJ, Schaffer JV, et al. Dermatology. 3rd Philidelphia. Elsevier;2012. p. 281-287.
- Neill BC, Neill JA, Brauker J, et al. Postexposure prevention of Toxicodendron dermatitis by early forceful unidirectional washing with liquid dishwashing soap. JAAD Online Clinical Pearl.Feb 2019;81(2):E25.
- Stibich AS, YAgan M, Sharma V, et al. Cost-effective post-exposure prevention of poison ivy dermatitis. Int J Derm.Dec 2001;39(7):515-8.
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