Poison Ivy vs. Poison Oak: What Are the Differences?

Spending time outside is great for physical and mental health. However, it comes with some risks, including exposure to poison ivy and poison oak. Many people wonder whether they may have a poison ivy vs. a poison oak rash. But once you have symptoms, which plant caused them isn’t particularly important. That’s because both rashes are caused by the urushiol oil that the plants produce. The symptoms and treatments are the same.

This article will cover poison ivy vs. poison oak rash. It will explain why both conditions have similar symptoms and when to seek treatment. 

Symptoms

Poison ivy and poison oak rash are both characterized by an itchy, blistering rash that appears on the skin. The blisters on the skin often break open and weep or pus. You may also experience red dots and areas of redness. Sometimes, people may have a rash with black spots or black streaks. This is known as black-spot poison-ivy dermatitis.

The rash does not spread on your skin. After you’ve been exposed to poison ivy or oak, it may take different amounts of time for the rash to appear on different areas of your body. This can make you think that the rash is spreading or getting worse.

Whether you have poison ivy or poison oak, the rash will be the same.

Causes

Both poison ivy and poison oak rash are caused by urushiol oil. Poison ivy and poison oak produce a chemical called urushiol found mostly on their leaves. More than 85% of people are allergic to urushiol and will get a rash even if they come into contact with an amount smaller than a grain of sand.

In short, poison oak and poison ivy rash are both allergic reactions to urushiol. They are also considered a form of allergic contact dermatitis. Scientifically and medically, poison ivy and poison oak are known as rhus dermatitis. “Rhus” refers to an older genus name for these plants. 

You might not get a rash the first time you’re in contact with urushiol oil, or the rash might appear two to three weeks after exposure to urushiol oil. After you have been sensitized or exposed to the oil, the rash will appear four to 48 hours after the oil touches your skin.

In addition to getting the rash from the plants, you can get it from other items and materials with urushiol oil on them that have come in contact with the plants or another person who has been exposed. This includes clothing, pets, or tools, really anything that's been exposed to the plants. If you or someone in your house has been exposed to poison ivy, wear gloves to carefully wash any items that might have come into contact with the plants. 

Diagnosis

Poison ivy and poison oak are diagnosed by looking at the pattern of the rash. Many people can diagnose the rash themselves if they’ve had it before. However, you should see a healthcare provider if you’re not sure what caused your rash. You should also see a healthcare provider if the rash is on your face or genitals.

Treatment

The rash from poison ivy and poison oak usually lasts about 10 days to three weeks. During that time, treatment is focused on making you more comfortable and reducing the itchiness from the rash. Treatments for poison ivy and poison oak rash are the same.

To treat poison ivy or poison oak, follow these steps:

• Wash your skin with soap and water. If you can do this immediately after you touch the plant, you may be able to remove some of the oil and reduce symptoms.
• Use cold compresses. Apply them for 15–30 minutes at a time, particularly during the first three days of the rash. Lukewarm baths can also help.
• Apply steroid creams. Hydrocortisone cream can reduce inflammation and redness. If you need a more powerful steroid cream, talk to your doctor. 
• Use anti-itch cream. Calamine lotion can help, but don’t apply too much or it may dry out your skin. 

When to See a Healthcare Provider

Some people can have severe reactions to poison ivy or poison oak. You should see a healthcare provider if you have:

• A rash on your face or genitals, or if the rash covers more than 25% of your body
• A fever of 100 degrees F or higher 
• Yellow pus or a rash that is painful to touch
• Itching that keeps you awake at night
• Difficulty breathing or any other alarming symptoms

Your healthcare provider may prescribe oral steroids to help fight the rash if it is severe. 

Prevention

Since there are few treatment options for poison oak or poison ivy, prevention is important. The best way to prevent the rash is to know what the plants look like and avoid them:

Poison Ivy:

• Found throughout the continental United States, except some areas of the West Coast
• Vine or short shrub
• Leaves with three glossy sections 
• Leaves that are reddish in the spring, green in the summer, and green, red, or orange in the fall
• Sometimes has white flowers

Poison Oak:

• Grows in tall clumps or on long vines in California and the Northwest
• Can grow in low shrubs in the eastern and southern United States
• Fuzzy green leaves with three sections 
• Sometimes has yellow-white berries 

Once You’ve Been Exposed

If you or other household members have come into contact with poison ivy or poison oak, taking action can help prevent more exposure. Once you know you’ve been exposed:

• Wash the skin with soap and water. 
• Find a pair of gloves. Then, remove your clothes and wash them immediately. 
• Wear gloves, wash pets, tools, and any other items that may have come into contact with the oil.

Summary

Poison ivy and poison oak both cause a blistering red rash that sometimes can appear with black spots too. The rash is caused by urushiol oil, a chemical these plants release. More than 85% of people are allergic to urushiol oil and will react if they are exposed. Once you have the rash, it can last up to 10 days or longer. Treatment is focused on controlling the itch through creams, cold compresses and baths.