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Plants that cause rash: How to identify and treat common plant rashes

How to identify and treat common plant rashes



How to identify and treat common plant rashes

Whether you enjoy hiking, doing yard work or just being outside, it’s likely that you’ll eventually encounter some of the Tri-state Area’s least favorite plants: poison ivy, poison oak and poison sumac. Learn how to spot the plants and what to do if you accidentally touch them.

What do poison ivy, poison oak and poison sumac look like?

There’s a reason for the saying “leaves of three, let it be.” That’s because both poison ivy and poison oak commonly have three green leaves per stem. Poison sumac, on the other hand, can have anywhere between seven and 13 leaves. See the differences here.

Why do poison ivy, poison oak and poison sumac cause a rash?

The plants are part of the Toxicodendron genus—a family of plants characterized by its mixture of oil and resin known as oleoresin. Within this oleoresin is a chemical called urushiol. Urushiol is allergenic, so much so that a rash develops in up to 90 percent of people who come into contact with as little as 50 micrograms of it. For reference, that’s less than one grain of table salt!

How can I tell if I have a rash from urushiol?

A urushiol rash usually has a linear (line-like) appearance. The rash may appear flat and red or as large blisters. What it looks like specifically, and how much area the rash covers, depends on how much poison ivy, poison oak or poison sumac you touched or if you previously were ever exposed to urushiol.

Will my rash spread from itching it?

Some people believe that itching or scratching a urushiol rash can make it spread on the body. This isn’t true. If it seems like poison ivy, poison oak or poison sumac rash is spreading, this is because of the amount of urushiol you touched.

For example, if you get a lot of urushiol on one part of your body, your immune system will recognize this large dose first and blossom a rash there more quickly. Other areas where you encounter less urushiol will take longer for a rash to pop up, making it seem like your rash is growing over time. (It can take up to three weeks for a rash to appear if you’ve never come into contact with urushiol before.)

Regardless, the next time you are exposed to urushiol, your body will already have immune cells waiting to make a rash. This means that with each subsequent exposure to urushiol, your rash will likely appear faster and be worse.

So, urushiol rashes aren’t contagious?

That’s right. While poison ivy, poison oak and poison sumac rashes aren’t contagious, urushiol can be spread by contaminated surfaces. Think dogs or cats. The oleoresin that contains urushiol can sit on an animal’s fur without causing a rash and then transfer to you.

What should I do if I touch poison ivy, poison oak or poison sumac?

If you have a known exposure to the plants, flush the area with plenty of water. And be sure to act quickly. After 10 minutes, you’ve missed your window of opportunity to rinse off and a rash will form. It’s also important to keep in mind that soap and alcohol can expand the area of oleoresin on your body, so don’t immediately use these substances. Stick to water.

What else can I do to treat a urushiol rash?

As for at-home treatments, taking a cool bath and applying calamine lotion can help. If your rash covers a lot of skin, talk to your healthcare provider about your options. They can help you understand the most effective treatments, including a prescription oral steroid that’s taken for two to three weeks.

Pictures of Rashes & Plants

Medically Reviewed by Dan Brennan, MD on November 25, 2022

Fact. Poison ivy, poison oak, and poison sumac grow in wooded or marshy areas throughout North America. The plants aren’t really poisonous. They have a sticky, long-lasting oil called urushiol that causes an itchy, blistering rash after it touches your skin. Even slight contact, like brushing up against the leaves, can leave the oil behind. Poison ivy and poison oak grow as vines or shrubs. Poison sumac is a shrub or tree.

Myth. Poison ivy is the only one that always has three leaves, one on each side and one in the center. They’re shiny with smooth or slightly notched edges. Poison oak looks similar, but the leaves are larger and more rounded like an oak leaf. They have a textured, hairy surface. There may be groups of three, five, or seven leaves. Poison sumac leaves grow in clusters of seven to 13 leaves, with one by itself at the end.

Myth. It forms within 24 to 72 hours of contact, depending on where the plant touched you. It usually peaks within a week, but can last as long as 3 weeks. A rash from poison ivy, oak, or sumac looks like patches or streaks of red, raised blisters. The rash doesn’t usually spread unless urushiol is still in contact with your skin.

Myth. It’s usually safe to breathe where poison plants grow. But if you burn them in your yard, the smoke could cause problems. When poison ivy leaves burn, they put out chemicals that can bother your eyes, nose, or lungs. You may need to see a doctor if you breathe the smoke. They’ll prescribe steroids to control your symptoms.

Fact. Keep your skin covered to avoid contact with these plants. Wear a long-sleeved shirt, long pants, gloves, and closed shoes if you’re in an area where they grow. Tie the bottoms of your pants legs or tuck them into your boots. Wear gloves when you handle bagged mulch or bales of pine straw. Keep a pair of shoes just for outside use and keep them outdoors. Try a lotion that has bentoquatam. It acts as a barrier between urushiol and your skin.

Fact. Urushiol begins to stick within minutes. If you know you’ve made contact with poison ivy, oak, or sumac, wash the area with lukewarm water and soap ASAP. If there’s no water, rubbing alcohol or alcohol wipes can remove it. Keep the area cool, dry, and clean. Wash your clothes and clean your boots or shoes. Hose down any garden tools that might have touched the plant.

Myth. But using them along with over-the-counter medicine can ease the itch and keep you more comfortable. Once a rash appears, keep it clean, dry, and cool. Calamine lotion, diphenhydramine, or hydrocortisone can help control itching. Cool compresses or baths with baking soda or oatmeal can also soothe the rash. Don’t scratch. It won’t spread the rash, but can cause scars or infection. Your doctor may suggest other treatments for your symptoms.

Myth. If someone in your household has poison ivy, oak, or sumac, you can’t catch it from them, even if you come into contact with the blisters. Just because you’ve never had a rash from one of these plants doesn’t mean you’re in the clear. Most people — about 85% — are allergic to urushiol. You can be affected by it at any age.

Myth. See your doc if the rash is close to your eyes or is widespread over your body. If needed, they can prescribe medications you take by mouth that will help with swelling and itching. Head to the emergency room if you have severe reactions in addition to the rash, like nausea, fever, shortness of breath, extreme soreness at the rash site, or swollen lymph nodes. Call 911 if you have any trouble breathing or feel faint.

Fact. A dog’s or a cat’s fur usually protects its skin from urushiol. But it can stay on the fur and rub off on you. If your pet explores areas where these plants are found, bathe them with soap and cool water. Be sure to wear gloves.

Myth. Don’t burn poison ivy, oak, or sumac. Particles of urushiol remain in the smoke and can aggravate your eyes, nose, and respiratory tract, and can land on the skin. Instead, dress appropriately and dig out the plants, getting as much of the root as possible. Put them in a plastic trash bag and throw it away. Have someone else do this if you’re super-sensitive to the plant. Some plant killers may work. Read the label carefully and use it at the right time of the year. Be careful — urushiol remains active, even on dead plants.


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American Academy of Dermatology: “Poison Ivy, Oak and Sumac.”
Asthma and Allergy Foundation of America: “Poison Plants.”
Occupational Safety and Health Organization (OSHA) Fact Sheet: “Working Outdoors in Warm Climates.”
University of Connecticut Integrated Pest Management: “Dealing With Poison Ivy.”
University of Oregon Health Center: “Facts & Fiction About Poison Oak and Ivy.”

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Burning “imprint”. What plants can be dangerous to humans? | HEALTH

Lilac Babaeva

Estimated reading time: 5 minutes


No. 25. “Arguments and facts in Western Siberia” 06/22/2017

“Imprint” from plants. What plants can be dangerous to humans? AiF

With the onset of hot days, more and more Tyumen residents began to turn to doctors with burns, blisters, redness after contact with herbs. The influx of such patients occurs only in sunny, hot weather, and up to seven people consult only one dermatologist per day.

Mostly summer residents suffer from phytophotodermatitis, but any person can have a reaction from contact with plants after walking outside the city, swimming in flowering water and even walking barefoot on the grass. Doctors expect mass appeals during haymaking.

“Phytophotodermatitis combines two reactions at once: to the sun and plants. They are combined because the sun affects the plants. In hot weather, under the influence of sunlight, they release essential oils, and when a person sweats, his sweat gland ducts expand, which contributes to the penetration of the allergen from plants into the skin. That is why such diseases practically do not occur in cloudy weather, ”says Lyubov Makarova, a specialist in medical prevention at the regional Dermatovenerologic Dispensary.

Backache ordinary (sleep-grass) causes burns on the skin. Photo: From the personal archive / Elena Kozhina

Most often, such a reaction is caused by sedge, cow parsnip, primrose and others. These plants produce allergenic essential oils.

Without contact

As a rule, signs of illness appear immediately after contact with the plant or throughout the day, in some cases on the second or third day. After exposure to the allergen, edema may occur, after it – small bubbles, the opening of which leads to micro-ulcers with a clear liquid in the middle. Necrotic ulcers may appear on the skin, affecting not only the upper layers, but also extending deeper and leading to scarring. And after recovery, age spots may remain in this place.

Phytophotodermatitis blisters are often confused with signs of food allergies and even burns.

“Sometimes, patients come and say that they apparently burned themselves somewhere and did not notice it themselves, but in fact it is phytophotodermatitis,” says Lyubov Makarova.

Most often, the rash appears on the feet, hands and knees – in those areas that come into contact with the grass.

The treatment of the disease is individual and depends on the area and depth of the lesion. With phytophotodermatitis, the first thing to do is to stop contact with the plant that caused it. Most often, it is treated topically, with the help of ointments, lotions and powders. It is also forbidden to sunbathe at this time, both in the sun and in the solarium.

To prevent phytophotodermatitis, try not to contact the grass on sunny days, do not lie on it without bedding, try not to walk barefoot and not swim in a flowering pond.


Which herbs are better not to touch?


Its juice, if it comes into contact with the skin, can cause severe burns, up to I degree of severity. It is especially dangerous at the time of flowering in sunny weather. Sometimes, after a couple of minutes, under the influence of sunlight, in the place where the hogweed juice got into, inflammation begins and a bubble swells. With prolonged exposure, deep, long-term non-healing ulcers form, leaving scars.

Larkspur (Delphinium)

Poisonous plant from the insidious ranunculus family. May cause allergic reactions (burning and itching) on ​​contact with unprotected skin. If you are breeding delphiniums as ornamental flowers, wear gloves when handling them. And do not allow children to pick beautiful flowers.

Ash tree (burning bush)

The vapors of essential oil released during the maturation of seeds in the heat can severely burn even at a distance of up to two meters.

Meadow parsnip

Causes almost the same burns as hogweed. Once in the meadow, pay attention to light greens on 1.5-meter stems with inconspicuous flowers of the same color – do not touch it.


It is no coincidence that wild and domestic animals bypass these yellow flowers. The poisonous buttercup juice causes irritation, itching, and blisters on the skin. So it’s not worth collecting bouquets from them and even smelling them.

Backache (dream-grass)

Another relative of buttercup. Both wild and cultivated species are poisonous. The juice causes burns on the skin in the form of redness, blisters and abscesses.


Which plants can cause phytophotodermatitis? Nettle, sedge, spurge, primrose, hogweed

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Phytophotodermatitis – rashes from plants – Articles

Phytophotodermatitis – rashes from plants

in childhood, before a walk, did my mother tell us not to pick unfamiliar flowers and plants and not to climb into various thickets? And this was done for a reason, but because many plants that seem harmless can be very poisonous. What is one cow parsnip worth. Such a beautiful name, but on contact you can get not just a burn, but phytophotodermatitis. And quite a lot of different plants are capable of this. Today in the article we will talk about what phytophotodermatitis is, what to do if contact has already happened, and we will also tell you which plants to be wary of.

What kind of animal? Description

Phytophotodermatitis is a skin reaction to contact with a certain plant and parallel exposure to solar radiation. This reaction is caused by substances contained in plants – furanocoumarins.

Plants causing such a reaction belong to the families Umbelliferae, Rosaceae, Leguminous, Rue. For example, hogweed. In addition to hogweed, plants containing such substances include parsley, celery, parsnips, carrots, figs, limes, lemons, bergamot, and some types of wildflowers. Not all of these plants cause a strong reaction, but they may well.

Phytophotodermatitis occurs within 24 hours after contact with the plant, it is worth noting that contact may be short-term and unnoticed. The strength of the reaction depends on the amount of plant juice, the concentration of furanocoumarins, or rather their compounds – psoralens in them, as well as the strength of ultraviolet radiation.

How does it manifest itself?

First, a person comes into contact with the juice of the plant, and then the affected area of ​​the skin is exposed to the sun. After a few days, the skin area darkens in the form of spots that have clear boundaries. At this stage, discomfort is usually absent. After a while, blisters swell in this place, which in no case should be pierced. After the blister itself opens or the liquid inside it is absorbed, the bubble begins to hurt badly. The sensations are more like burning and pain than itching.

After a while, a trace of pigmentation remains in place of the blister, which is difficult to remove. Since it is almost impossible to influence the pigmentation, you can use protection from UV radiation so as not to aggravate the process. UV protection, by the way, protects against the appearance of phytophotodermatitis, it is important to use it before a walk.

If phytophotodermatitis has already happened: algorithm

In the case when contact with the plant sap has already happened and you notice it, you need to wash the affected area as soon as possible with plenty of soap and water. Then, for the next 14 days, apply UV protection to the affected area and cover it with clothing, since it cannot be exposed to solar radiation, in order to avoid burns and phytophotodermatitis.

If contact happened, you did not notice it in time, but you already found blisters, then you should not open them, because not only will the place be very painful, but there will also be a risk of a secondary infection. You can wrap this place with a bandage so that mechanical damage does not happen.

After the blister resolves itself, the place where the blister is located will start to hurt and burn. Cold compresses can help relieve the condition. With severe rashes, anti-inflammatory steroid drugs, which will be prescribed by a doctor, will help. Since we cannot influence a significant regeneration process, it is necessary to relieve pain with ibuprofen or paracetamol and drink plenty of fluids.

If there is itching, redness, irritation, then topical corticosteroids will be the first-line drugs; in mild cases, cooling creams and talcs with zinc, Calamine lotion will help.

In some cases where lesions are very large, hospitalization and hospitalization may be necessary.

How to protect yourself?

If we are talking about our own garden plot, then it is necessary to eradicate poisonous plants, for example, cow parsnip. Be sure to tell the children and all family members about its harm and explain that its flowers, leaves, tops are not a toy, it is a danger and poison.

When destroying hogweed thickets, be sure to protect yourself with waterproof clothing with long sleeves and trousers. It is better to do this in cloudy weather, and pay attention to the UV index, the strength of the sun’s effect on the skin depends on its value.

If there are no such plants on the site, but there are in the area, then be sure to instruct at home, especially with children, and remind them of the danger of such plants before the walk.

And don’t forget about UV protection, that is, creams. Choose a cream with maximum sun protection, i.e. SPF50. Creams, where the figure is above 50, is already a marketing ploy. It is important to renew your sunscreen every 2 hours of sun exposure.

So which plants are dangerous?

And now the most interesting thing – let’s talk about plants that can cause phytophotodermatitis. Not only hogweed is dangerous and poisonous.

  1. Sosnowski’s hogweed and ash. The juice of these plants contains furanocoumarins, which have a phototoxic effect, that is, they cause burns under the influence of the sun.
  2. Buttercup is caustic. Contains ranunculol, which can cause dermatitis.
  3. Marigolds. Yes, yes, those beautiful flowers in Grandma’s garden contain thiophenes, which cause phototoxic burns.
  4. Castor oil. The plant and all its parts contain ricin, which causes dermatitis. Especially a lot of this substance in the seeds. If swallowed, it causes severe poisoning.
  5. Ivy. It is also completely poisonous, causing burns and blisters, and if ingested, acute poisoning.
  6. Croton and spurge. The juice of these plants is similar to milk, when it comes into contact with the skin, it irritates it, and when it enters the body, it causes vomiting.
  7. Dieffenbachia. The juice of this plant is extremely dangerous if it enters the mouth, as it causes paralysis of the ligaments and loss of voice.
  8. Primula. It contains alkaloids that cause nausea and dizziness, and the juice of leaves and flowers can cause dermatitis.

Phytophotodermatitis is a skin reaction to contact with a poisonous plant and simultaneous exposure to solar radiation.