Eczema vs. Poison Ivy: What Are the Differences?

Eczema is a catch-all term that describes several skin conditions causing similar symptoms, including itching, dryness, and blisters. There are several types of eczema, such as atopic dermatitis and allergic contact dermatitis.

Atopic dermatitis is a common skin condition that causes eczema symptoms and can become chronic. Poison ivy is a plant that causes a skin reaction known as allergic contact dermatitis when you touch it. Though the two cause very similar symptoms, they are distinct.

This article will discuss the differences between chronic eczema and a poison ivy rash, including symptoms, causes, diagnosis, treatment, and prevention. 

Symptoms

Common symptoms of atopic dermatitis and allergic contact dermatitis rashes include:

• Itchy skin
• Sensitive, overly dry skin
• Inflammation and discoloration
• Crusting or oozing pustules or sores
• Swelling 
• Scaly patches of skin

A poison ivy rash is a type of eczema called allergic contact dermatitis. Though many people experience a reaction to the oily coating on poison ivy plant leaves, the severity of the reaction may differ from person to person. 

A rash from poison ivy will appear only in places where the skin was exposed to oil from the plant. The rash does not spread, but the oil can transfer from clothing and takes only a tiny amount to cause a reaction. So, sometimes additional areas of rash appear after the first patch.

The time it takes for the rash to develop after contact can vary from as little as four hours to up to 10 days after contact. The rash will usually clear up on its own without needing treatment. The first time you react poison ivy, the rash may last a long time—sometimes up to four weeks.

Atopic dermatitis is a chronic skin condition. It starts with an itch. When scratched, a rash develops. It is more common in places that are easy to scratch, such as the flexural areas: the inside of the elbow, behind the knee, in front of the neck, behind the ears, and folds of the wrists and ankles. In babies, it may appear on the face.

A difference between allergic contact dermatitis is that the rash appears in places that had contact with the allergen, which can differ from the usual sites of atopic dermatitis. A poison ivy rash will be in the area exposed to the plant material.

Causes 

Allergic contact dermatitis results from the body’s immune response to a potential trigger. With a poison ivy rash, the trigger is obvious. The oil from the plant can cause a skin reaction. Other common triggers are metals, rubbers, or latex, fragrances in cosmetics and toiletries, preservatives, and adhesives.

Atopic dermatitis may be triggered in many ways. It can occur after your skin gets too dry, is injured, is exposed to heat or cold, or is in contact with an irritant. People with atopic dermatitis may also find that certain foods cause symptom flare-ups. Stress may also play a role in making symptoms worse.

One underlying cause of atopic dermatitis is a lack of protein in the skin called filaggrin due to a genetic mutation. Without this protein, the skin tends to become dry, itchy, and more vulnerable to allergens in the air, like dander and dust mites, which can lead to inflammation. 

Diagnosis 

Like many skin conditions, healthcare providers, including dermatologists (specialists in skin conditions), typically diagnose poison ivy rash and atopic dermatitis by visual inspection and taking a medical history.

They may ask whether you’ve been hiking or potentially exposed to poison ivy recently. No specific test can confirm a diagnosis of atopic or allergic contact dermatitis.

However, they may use patch testing to check for a reaction if they think your rash results from contact dermatitis. They may also order skin or blood testing to check whether you have allergies because atopic eczema is more common in people with allergies.

Treatment 

Treatment for atopic dermatitis and poison ivy rash is similar. Both aim to reduce inflammation and symptoms such as itching and pain. 

Some common treatment options include:

• Keeping the skin moisturized and avoiding products that make symptoms worse are recommended for atopic dermatitis.
• Cool, wet compresses can help relieve poison ivy rash.
  
• Topical steroids are for atopic dermatitis and allergic contact dermatitis. For treating poison ivy, over-the-counter (OTC) topical hydrocortisone is also an option. Prescription topical steroids may be necessary. Oral steroids may be prescribed in cases of severe or widespread allergic contact dermatitis.
• Antihistamines can help with itching. They may be topical or oral. 
• Topical calcineurin inhibitors such as Elidel (pimecrolimus) and Protopic (tacrolimus) can help with atopic dermatitis and severe cases of contact dermatitis.
• Light therapy may help with severe, recurring symptoms that don’t respond well to other treatments.

Prevention 

Though you can sometimes prevent atopic dermatitis symptom flare-ups by avoiding triggers, it’s not possible to prevent this condition altogether.

With allergic contact dermatitis, avoiding the triggering allergen can prevent the rash. Here’s how to recognize the poison ivy plant:

• It’s common throughout most of the United States.
• It grows as a vine or shrub.
• Each leaf has three leaflets. 
• The edges of the leaves are either smooth or toothed. 
  

To avoid exposing yourself to poison ivy, learn what these plants look like. If you plan on gardening, working, walking, or hiking near poison ivy plants, make sure to protect your skin by wearing long pants, long sleeves, and gloves. 

If you come into contact with the plant, promptly wash your skin with soap and water. Launder any clothing that may have come in contact with the plant. Regularly clean any gardening tools, gloves, or boots that may have contact with the plant.

Summary 

Eczema is a group of conditions that cause itchy, dry skin. A poison ivy rash is a type of eczema called allergic contact dermatitis. It occurs where the skin has come into contact with oil from the plant. It typically produces an itchy rash with fluid-filled blisters.

Another very common type of eczema is atopic dermatitis. This chronic condition causes inflammation and symptoms similar to those of a poison ivy rash, but it mostly occurs on flexural surfaces that are easy to scratch and is more common in children.

Typically, recent exposure to poison ivy will make it clear that your rash is the result of touching the irritating plant. Treatment for both types of rashes is similar, including topical steroids and medications and remedies for atopic dermatitis or severe cases of poison ivy rash.

Though a poison ivy rash will recur without exposure to the plant, atopic dermatitis can recur.

A Word From Verywell 

Rashes are sometimes tough to identify, so if you have a rash that isn’t going away and you haven’t had a known recent run-in with poison ivy, it’s a good idea to see a healthcare provider or get a referral to a dermatologist.