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

Poison ivy and poison oak rashes are both caused by the urushiol oil that the plants produce. When the oil gets on your skin, it can cause a rash if you are sensitive to it. The severity of the symptoms differs from person to person, but you can usually treat the condition at home with over-the-counter medications. In severe cases, you may need to see a healthcare provider.

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 of Poison Ivy and Poison Oak Rashes

There is no difference between a poison ivy vs. a poison oak rash. The stages of this rash include:

• Th skin itches.
• A red rash occurs, sometimes with swelling.
• Blisters appear with a clear liquid inside.
• Healing: Eventually the blisters break, weep, or ooze, and become crusty.

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.

Causes of Poison Ivy and Poison Oak Rashes

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 directly from the plants, you can get it from any items and materials that have come in contact with the plants. This includes:

• Your clothing or the clothing of others
• Shoes
• Pets
• Tools
• Anything that has touched 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. 

Treatment of Poison Ivy and Poison Oak Rashes

Treatments for poison ivy and poison oak rash are the same. 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.

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.
• Wear gloves. Then remove your clothes and wash them immediately.
• Prevent more exposure. Wear gloves to wash pets, tools, and any other items that may have come into contact with the oil.
• 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

Poison ivy and poison oak are diagnosed by looking at the pattern of the rash. Some people can have severe reactions to poison ivy or poison oak. You should see a healthcare provider if you’re not sure what caused your rash or 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.

Identifying Poison Ivy

These characteristics can help you identify poison ivy:

• It's found throughout the continental United States, except in some areas of the West Coast, Alaska, and Hawaii.
• The vine or small shrub can be found trailing along the ground or climbing on low plants, trees, and poles.
• Leaves have three glossy sections. 
• Leaves are reddish in the spring, green in the summer, and green, red, or orange in the fall.
• It sometimes has greenish-white flowers and whitish-yellow berries.

Identifying Poison Oak

Look for these characteristics to identify poison oak:

• It grows in tall clumps or on long vines in California and the Northwest.
• It can grow as a low shrub in the eastern and southern United States.
• Fuzzy green leaves have three sections. 
• It sometimes has yellow-white berries. 

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. If the rash is severe, your healthcare provider may prescribe oral steroids.