How to spot poison ivy

With summer just around the corner, it’s time to get outside and enjoy the warm weather that Mother Nature has to offer. When spending time outdoors, it's important to be mindful of a poisonous plant called poison ivy, which can cause an itchy skin rash. These plants produce an oily sap containing urushiol, which triggers skin irritation and itching (4). The best way to identify poison ivy is to examine the leaves. First, check if the plant has three leaflets; second, see if the middle leaflet's stem is longer than the side leaflets. Poison ivy can grow as a climbing or strangling vine or sprawling shrub, and its appearance varies with the seasons (3). 

In the summer, the leaves are typically green, while in the spring they may appear reddish. The leaves turn red, yellow, or orange in the fall and the plant may also produce white berries (1). Poison ivy exists throughout the United States, except in Hawaii and Alaska. The plant is commonly found in woodlands, fields, pastures, farms, and home landscapes (2).

Encountering Poison Ivy 

About 85% of the population is allergic to poison ivy, with 10–15% being extremely allergic. Identifying this plant is essential, as it only takes 50 micrograms of urushiol—less than a grain of salt—to cause an itchy reaction (1). Age does not affect sensitivity to poison ivy, meaning anyone who encounters it can experience a reaction. Some summer activities that may lead to encounters with poison ivy include hiking, camping, farming, gardening, or yard work. Therefore, it is important to keep an eye out for the three-leafed plant when participating in outdoor activities.

Symptoms

If you come into contact with poison ivy, wash the oil off your skin immediately with soap and water to reduce the chances of developing an itchy rash. If you are unaware of the contact, a rash will typically begin to appear 12–48 hours after exposure. Symptoms may include redness, itching, swelling, blisters, and—if smoke from burning poison ivy is inhaled—difficulty breathing. The rash often appears in a straight line, usually from brushing against the plant directly, but it can also be more spread out if you've touched clothing, pet fur, or other objects that have urushiol on them.

Treatments

There are several treatments for poison ivy, including anti-itch creams, calamine lotion, and hydrocortisone. If blisters begin to weep or drain, topical astringents made with aluminum acetate can be used. Antihistamines such as diphenhydramine may also help relieve symptoms. If the reaction becomes severe, your healthcare provider may prescribe an oral steroid, such as prednisone (1). 

 Relieving the itch

It is important not to scratch the affected area, as this can lead to potential infections. Instead, try a few simple at-home remedies to help relieve the persistent itch. One option is to take a clean washcloth, wet it with cold water, wring it out, and place it on the itchy area. Another remedy is to take a lukewarm bath with colloidal oatmeal, which can help soothe the skin. If the itching persists, consider using a steroid cream such as hydrocortisone and applying it to the affected areas (4).

Prevention

To prevent yourself from potentially contacting poison ivy make sure you can 

• Identify the plant 
• Stay on cleared pathways when hiking and wear socks, pants, and long sleeves
• Keep pets from running through wooded areas to prevent urushiol from sticking to fur 
• Remove or kill the plant by applying an herbicide or pulling it out by the roots using gloves (DO NOT BURN THE PLANTS) 
• Clean objects like clothing that have brushed against poison ivy

When to Seek Medical Attention

You should seek medical attention if the reaction is severe or widespread, your skin continues to swell, the rash affects your eyes, mouth, or genitals, blisters begin to ooze pus, you develop a fever over 100°F (37.8°C), or the rash does not improve within a few weeks (1). If your reaction is severe or if at-home remedies are not helping, schedule an appointment with your primary care provider or with one of our same-day clinics. 

References 

1. Cleveland Clinic. Poison Ivy, Poison Oak and Poison Sumac. 2023

https://my.clevelandclinic.org/health/diseases/10655-poison-plants-poison-ivy--poison-oak--poison-sumac

2. Children's Hospital of Philadelphia. Recognizing Poison Ivy, Oak and Sumac. 2025

https://www.chop.edu/news/health-tip/recognizing-poison-ivy-oak-and-sumac

3. University of Maryland Extension. How to Identify Poison Ivy. 2023

https://extension.umd.edu/resource/how-identify-poison-ivy/

4. American Skin Association. Poison Ivy, Sumac and Oak. 2020

https://www.americanskin.org/resource/poisonivy.php