How to Identify Skin Rashes from Weeds and Plants

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Many plants and weeds can cause rashes. People with sensitive skin may experience skin irritation when touching plant matter without protective equipment, like gloves. But some plants are more likely to lead to terrible itching than others. The poison ivy plant, for example, is well-known for causing a painful, itchy rash.

This article outlines several common rash-causing plants you should avoid, along with the symptoms to look out for and when to see a healthcare provider. 

Skin rash on arm from poison ivy plant. Poison ivy blisters on human arm from gardening outdoors.

Jena Ardell / Getty Images

Plants to Avoid

Poison Ivy, Poison Oak, and Poison Sumac

Most people are allergic to the oil found in poison ivy plants called urushiol. When it comes into contact with the skin, it causes a rash. Other plants that also contain this oil include poison oak and poison sumac. 

The severity of the rash will depend on how much contact you've had with the plant and for how long. 

Keep in mind that you may only get a minor rash or none at all after touching any of these. But it's possible for your reaction to be different the next time you come into contact with the plant, so be cautious regardless.

The rash happens after your skin touches the plant and you develop red, itchy bumps and blisters on your skin. If you have never been exposed before, it may take two to three weeks to develop the rash. If you've had the rash previously, it can appear within a few hours of exposure.

A rash from poison ivy tends to last about three weeks if you've never had one before or between one day and two weeks if you've had a previous rash from these plants.

Treatment typically involves waiting things out and managing the intense itching. Options to relieve itching include:

  • Cool compress
  • Antihistamine medication such as Benadryl (diphenhydramine)
  • Topical creams or lotions that contain calamine or hydrocortisone
  • Lukewarm oatmeal baths (1 cup of colloidal oatmeal in a tub of warm water, soak for 15 to 20 minutes)

Identifying Poison Ivy, Poison Oak, and Poison Sumac

Remember the rule: "Leaves of three, let it be." Poison oak and poison ivy look similar since they both have a three-leaf pattern on a stem. Poison sumac has clusters of leaves—usually seven to 13.

Poison ivy climbing on a treee

Douglas Sacha / Getty Images

Poison oak with leaves of three

Darren415 / Getty Images

Poison sumac

Katie Dobies / GettyImages

Wood Nettle (Stinging Nettle)

This perennial (meaning it regrows each year) plant’s stinging hairs contain toxins that cause skin irritation upon contact. Both the leaves and stems have these tiny irritating hairs.

Itching, rash, and hives (raised, red, itchy bumps) can happen soon after the hairs touch your skin. Fortunately, the itching and burning that occurs after touching stinging nettle usually subside within a few hours.

Identifying Wood Nettle

Wood nettle, or stinging nettle, can grow up to 5 feet tall and has toothed leaves with pointy ends.

stinging nettle is a green weed with serrated leaf edges that grows in gardens

Treehugger / Nadia Hassani


You’re probably aware that ragweed can cause allergies of the sneezing and sniffling kind, but did you know the plant can also cause skin irritation? If you’re allergic to ragweed, you might also experience hives if you come into physical contact with the plant or its pollen.

Identifying Ragweed

There are different species of ragweed, but common ragweed is a tall plant with fern-like leaves. In late summer, the plant also produces green flowers.

Blurred person holds tissue to their nose in response to ragweed

Roy Morsch / Getty Images


Leadwort, or plumbago, is a shrub that’s often planted as a hedge. If you come into contact with the shrub’s sap, leaves, stems, or roots, you may experience a skin reaction that causes blistering and a rash.

Identifying Leadwort

This plant with a climbing growth habit has flower clusters that can be blue, white, or pink.

Plumbago in bloom

Icy Macload / Getty Images

Baby’s Breath

These delicate-looking flowers often show up in flower arrangements. They’re pretty, but their pollen can trigger allergies, and the sap can cause a nasty skin reaction that leads to a rash.

Identifying Baby's Breath

This perennial plant grows up to 3 feet tall and features branching clusters of hundreds of tiny white flowers.

Baby's breath

Neringa Simanskaite / EyeEm / Getty Images

Giant Hogweed

The sap of this tall plant with large flower clusters can cause severe skin irritation in some people. If you get giant hogweed sap on your skin and stay in the sun, the combination of the two can lead to painful skin blisters. In some people, the sap can also produce black or purple scarring. 

If you encounter giant hogweed sap, be sure to cover the area until you can get out of the sun and wash off the clear, watery fluid as soon as possible. 

If you have minor burns from the plant, try applying aloe vera or other topical creams to soothe the skin and reduce swelling. Serious irritation warrants a visit to your healthcare provider.

Once the skin is exposed to hogweed sap, it’ll be more sensitive to the sun. This increased sun sensitivity can continue for years.

Identifying Giant Hogweed

This very tall umbrella-shaped plant is topped with wide flower clusters. It can grow up to 14 feet tall and has very big leaves that span up to 5 feet across.

Giant hogweed in bloom
Giant hogweed in bloom.

lucentinus / Getty Images

Symptoms of a Plant Rash

Many rashes have a similar appearance. But if you develop a rash after coming into contact with a plant, the plant material is the likely culprit. 

Plant rashes may also:

  • Be red in color
  • Involve bumps or streaking
  • Produce blistering 
  • Cause skin swelling 
  • Cause severe itching

General Treatment

Plant rash treatment largely depends on the severity of the rash. But the following first aid tips apply for most situations:

  • Wash off the area with dishwashing soap to remove any plant oils that may cause irritation.
  • Wash your hands to avoid spreading the rash to other areas.
  • Manage the pain and itching with topical creams or lotions, antihistamines, cool compresses, or oatmeal baths.

When to See a Healthcare Provider

You should see your healthcare provider if you’re not sure of the cause of your rash. A doctor’s visit is also a good idea if the rash isn’t going away or you suspect infection. Signs of a skin infection include redness, swelling, sores, and pus.

An infection may occur when the plant rash becomes infected by bacteria, or you may have an infectious rash rather than a plant rash. You may have other signs, such as a fever, with a rash due to an infection.

If you have a severe allergic reaction that makes it difficult to breathe, call 911 or get taken to the emergency room. 


Many plants can cause skin irritation that can lead to a rash. These include poison ivy, poison oak, poison sumac, stinging nettles, ragweed, leadwort, baby's breath, and giant hogweed. Often, treatment involves managing the symptoms until the rash goes away. 

16 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Dermatology Association. Poison ivy, oak, and sumac: Who gets a rash and is it contagious?

  2. American Academy of Dermatology Association. Poison oak, ivy, and sumac: What does the rash look like?

  3. American Academy of Dermatology Association. Poison ivy, oak, and sumac: How to treat the rash.

  4. Missouri Department of Conservation. Wood nettle (stinging nettle).

  5. Baumgardner DJ. Stinging nettle: The bad, the good, the unknownJournal of Patient-Centered Research and Reviews. 2016;3(1):48-53. doi:10.17294/2330-0698.1216

  6. Iowa State University. Recognition and avoidance of toxic plants.

  7. American Academy of Allergy Asthma & Immunology. Ragweed plants packed with pollen.

  8. Cornell University. Common ragweed.

  9. Queensland Government. Plumbago (plumbago auriculata).

  10. North Carolina Extension Gardener. Plumbago auriculata.

  11. Texas capital. Worst flowers and plants for people with allergies.

  12. Minnesota Wildflowers. Gypsophila paniculata (baby's breath).

  13. New York State Department of Health. Giant hogweed - Health advice.

  14. New York State Department of Environmental Conservation. Health hazards & safety instructions for giant hogweed (with graphic photos).

  15. New York State Department of Environmental Conservation. Giant hogweed identification.

  16. National Insitute for Occupational Safety and Health (NIOSH). Poisonous plants: Symptoms and first aid.

By Steph Coelho
Steph Coelho is a freelance health and wellness writer and editor with nearly a decade of experience working on content related to health, wellness, mental health, chronic illness, fitness, sexual wellness, and health-related tech.She's written extensively about chronic conditions, telehealth, aging, CBD, and mental health. Her work has appeared in Insider, Healthline, WebMD, Greatist, Medical News Today, and more.