Poison Ivy Rash: What It Looks Like and How To Prevent It

The rash caused by poison ivy looks like red blotches or streaks. There may also be clusters of tiny blisters. The rash can be very itchy.

In the United States, poison ivy, poison oak, and poison sumac are among the most common causes of contact dermatitis. Medically, the rash is known as Rhus dermatitis.

You can take steps to deal with poison ivy, poison oak, or poison sumac at home, usually without the assistance of a healthcare provider. Relieving the rash usually involves washing the area with soap and water and applying creams to help reduce inflammation and soothe itching.

This article provides pictures of a poison ivy rash to help you identify it. It also explains how the rash develops and how to get rid of poison ivy and avoid getting it again.

What Do Poison Ivy and Its Relatives Look Like?

The three main types of plants that cause Rhus dermatitis vary in both their appearance and geographic location.1

• Poison ivy leaves are most often notched on the edges and arranged in groups of three (although some varieties are smooth-edged). Poison ivy is found throughout the continental United States, except for parts of the West Coast.
  
• Poison oak leaves grow in groups of either three, five, or seven. The leaves are smaller than poison ivy and have smooth, rounded edges. Poison oak grows as a small shrub in the eastern and southern U.S. and as a taller plant or vine on the West Coast.
• Poison sumac has seven to 13 leaves on one stem pointing at an upward angle. They are oval, smooth-edged, and about 10 centimeters long. Poison sumac is found in boggy areas in the Northeast, Midwest, and South.

Poison Ivy Rash Pictures

A poison ivy rash commonly appears as red, itchy patches. Symptoms may develop within four hours to four days after exposure to the plant.2

For many people, the rash develops in stages:3

• Itching: The skin becomes itchy in the area where the rash will appear. The intensity if the itch may vary from person to person.
• Red rash: Soon after the itching starts, a red rash appears. It usually looks like a red streak or patch that may reflect how the plant brushed against your skin. Skin swelling may also be present.
• Blisters: Blisters may develop as the rash progresses. If you have blisters, they will crust over and the the rash typically goes away in two to three weeks.

This photo contains content that some people may find graphic or disturbing.

See Photo

This photo contains content that some people may find graphic or disturbing.

See Photo

This photo contains content that some people may find graphic or disturbing.

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How Poison Ivy Causes a Rash

Poison ivy, poison oak, and poison sumac are in the Anacardiaceae family in the Toxicodendron genus. These plants produce a resin called urushiol, which causes a skin reaction in most people.

A poison ivy rash occurs when a person comes into contact with the leaf and/or internal parts of the stem or root. It typically develops within 24 to 48 hours of exposure, though it can develop sooner or later depending on whether you've had a poison ivy rash before.4

The resin itself can be active for years following exposure (meaning that it can be spread to others who come into contact with the clothing of an affected individual). By contrast, the fluid from the blisters cannot spread the rash.1

Urushiol can also be found in the cashew tree, mango tree, Japanese lacquer tree, and the marking nut tree.5 Ginkgo biloba contains a similar substance that can cause dermatitis in people who are sensitive to urushiol.6

What to Do For a Poison Ivy Rash

There are several ways to manage a poison ivy rash at home. Many poison ivy products are available over the counter.1

• Wash the skin with soap and water to inactivate and remove the resin that causes the rash. Washing is most effective if it is done within 15 minutes of exposure.
• While rubbing alcohol can be used immediately after exposure to help remove the oil from your skin, it should not be used on a poison oak rash. This is because it can irritate the skin and make the rash worse.
• Cold, wet compresses can help relieve itching and inflammation. Apply these for 15 to 30 minutes several times a day.
• Steroid creams or ointments can help reduce inflammation and itching. Hydrocortisone can be used on the face; a stronger, prescription-strength steroid may be needed for the arms or legs.
• Oral steroids may be required for severe cases and must be taken for at least a week.
• Short, cool tub baths with colloidal oatmeal can be soothing and can help control inflammation.
• Calamine lotion can help control itching, although excessive use can dry the skin and cause even more inflammation.

Antihistamines such as diphenhydramine (Benadryl) that are sedating may help encourage sleep, but won't generally help itching. This is because the source of the itching in Rhus dermatitis is not primarily caused by histamine, but by white blood cell (lymphocytes) infiltration into the skin.8

Poison ivy mostly occurs on exposed areas on the arms, legs, and face. The intensity of the rash can vary based on the person's sensitivity to the resin, as well as the amount and/or extent of exposure. Rhus dermatitis is incredibly itchy, so much so that a person may scratch the skin to the point of bleeding.

When to See a Healthcare Provider

Untreated, the rash usually heals in around two to three weeks.3 Some cases, however, should be evaluated by a healthcare provider. See a doctor for a poison ivy rash if:

• You have a rash on your eyes, mouth, or genital area.
• You have pus or yellow scabs on the rash.
• The rash covers all or most of your skin.
• You have difficulty breathing.
• You have a fever over 100 degrees.
• The itch is all over your body and not just in the location of the rash.1
  

Tips for Preventing Poison Ivy

Clearly, the best way to avoid poison ivy, poison oak, or poison sumac is to know what the plants look like and to steer well of them. Beyond that, there are a few handy tips you should remember if you live in an area where the plants are endemic:5

• Clothing serves as the most effective barrier. Wear pants, socks, and boots if plants are known to grow in areas of heavy brush. If contact occurs, remove your clothes carefully and launder immediately.
• Use vinyl gloves when pulling weeds. Urushiol can penetrate rubber gloves.
• A lotion containing 5% quaternion-18 bentonite (IvyBlock) can be applied to the skin and provides protection for up to eight hours. It must be washed off before reapplying.

Note that despite popular beliefs, you cannot desensitize yourself to poison ivy by chewing leaves or being injected with commercially prepared extracts.9

Summary

A poison ivy rash occurs when a person comes comes into contact with urushiol, a substance produced by the plant. A poison ivy rash typically appears as red, itchy patches. Skin swelling and blisters may also be present. This type of rash usually resolves on its own within two to three weeks. Symptoms can be treated using simple home remedies and OTC medications such as hydrocortisone cream.