A Gardner's Nightmare: Poison Ivy

With warmer weather and COVID restrictions, more and more people are participating in outdoor activities, such as hiking and gardening. As you can imagine as a result, more and more people are visiting the dermatologists this summer for POISON IVY rash!

What is a poison ivy rash?

Poison ivy rash, also referred to as rhus dermatitis, is typically caused by contact (even limited) with a poison ivy plant. This type of rash may occur with contact with poison oak or poison sumac as these plants all contain an oil called urushiol.

When our skin is in contact with this oil this causes a "Type IV" or Delayed Hypersensitivity Reaction. What does this mean? This is an allergic reaction that occurs 24-72 hours after exposure to an allergen (in this case the urushiol oil). When the sap is in contact with our skin through our clothes or direct contact on the skin (when the leaf brushes against the skin) our body recruits certain immune cells that release substances called cytokines that cause fluid-filled bumps and pink-red welts.

What does a poison ivy rash look like?

Great question! This rash usually begins as pink-red itchy bumps usually linearly arranged. Think about the plant stroking your skin as a paintbrush stroke...with each stroke comes small bumps which often evolve into vesicles, which are fluid-filled bumps. This rash is extremely itchy and often weeps.

What if I find a black spot? What does that mean?

Some people may develop a small black spot or black streak on the skin in the middle of the rash. As the poison ivy sap is in contact with the skin, the chemicals in the sap oxidize in the air and form a black mark. This is not a permanent scar. It is important to contact your dermatologist if you do have a black spot as it may also represent a tick.

When does the rash appear?

As we mentioned above, the rash usually appears around 1-3 days. However, it can develop as early as a few hours if you had prior exposure to the plant before. In some individuals who have never been in contact with poison ivy, sumac or oak it can take as long as 2-3 weeks before the rash appears!

How long can I expect this rash to last?

Without treatment, if you have never had poison ivy contact in the past it can take about 2-3 weeks for the rash to resolve. With treatment, it can resolve within 1-10 days.

Can children have poison ivy dermatitis?

Yes, children and infants when exposed to poison ivy, oak or sumac can mount a similar immune response against this allergen. Children may sometimes have a more exuberant rash than an adult would. If your child is exposed to poison ivy, it is important to thoroughly wash all of their clothing and clothing of those in contact with the child to prevent further contact with sap.

Can I spread my rash to someone else?

The rash itself is not contagious meaning if a friend or loved one touches your skin they will not necessarily get the rash, unless they were exposed to the sap as well.

What if I was not in direct contact with poison ivy, but my dog or cat was possibly exposed, can I still get the rash?

Why yes you can! A common scenario is a household pet was playing around in a wooded area or a garden and then brushes against your skin. This frequently occurs and so it is important to bathe your household pet anytime you suspect potential poison ivy, sumac or oak exposure.

Let's talk about treatment:

The most important step: Wash your skin with water and soap as soon as possible to remove all sap from skin. Wash your clothes (including undergarments!) that you were wearing when you had contact with poison ivy. Make sure you either wear gloves or thoroughly wash your hands after contact with clothing and shoes.

When to treat at home vs see a provider:

When the rash is mild, you have identified contact with poison ivy (no other reason for the rash) and you are overall feeling well, the rash may be controlled with at-home over-the-counter creams and oral anti-histamines. However, when the rash is extensive, itching is interfering in daytime activities, work or sleep, and/or you feel unwell, have difficulty breathing, a fever, etc. it is important to contact your dermatologist and/or primary care physician for further care.

Topical and oral steroids:

Over-the-counter topical steroids may be helpful when you have limited exposure and a small area of the skin is affected. When the rash is more diffuse, spreading, itching worsens, it is important to contact your board-certified dermatologist to discuss prescription topical steroids and oral steroids. When prescribed oral steroids it is important to note that a short 3 week taper is often prescribed because with a 1 week course of oral steroids, the rash may recur and flare. It is important to discuss with your dermatologist if you are a candidate for oral steroids and the potential side effects.

Oral antihistamines:

Oral antihistamines are essential for controlling the itching. Over-the-counter non-sedating anti-histamines are important to take during the daytime and nighttime to help control the itching and rash.

Cool compresses and calamine lotion:

These at-home remedies will help soothe the itching. It is important to avoid itching the skin to prevent skin infection and scarring. Moisturizing our skin is essential. We recommend placing any moisturizers in the refrigerator to have a cooling effect on the skin with each application.

Don't pop the blisters:

Avoid popping the blisters and vesicles--they will crust over themselves with time. This may increase the risk for skin infection by opening the skin to skin bacteria.

How can I prevent contact with poison ivy?

  1. Wear protective clothing when hiking, outdoor activities, gardening in a wooded area.

  2. Wash clothing and rinse skin thoroughly after any potential contact with poison ivy, sumac or oak or when spending any amount of time in a wooded area. When washing your skin it is important to wash your hands and underneath nails thoroughly (especially if you were touching any plants).

  3. Clean gardening and/or hiking tools with soap and water.

  4. As we mentioned before, bathe your household pets.

  5. Educate yourself on whether or not your area is rich in poison ivy, oak or sumac. CLICK THE LINK BELOW PROVIDED BY THE AMERICAN ACADEMY OF DERMATOLOGY FOR A HELPFUL MAP.


Kunin A. "Poison ivy, oak, and sumac: Don’t let them ruin your great outdoors.” In: The DERMAdoctor Skinstruction Manual. Simon & Schuster. United States, 2005: 202-8.

Margosian E. “More than poison ivy: Identification and treatment of hazardous plant exposure.” Dermatol World. 2018:28(6):36-42.

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