Poison Ivy Rash

from MayoClinic.com

A poison ivy rash is a type of skin irritation called allergic contact dermatitis. Poison ivy rash is caused by a sensitivity to an irritant found in poison ivy and similar toxic plants, such as poison oak and poison sumac. Each of these plants contains an oily resin called urushiol (u-ROO-she-ol) that can irritate the skin and cause a rash.

Although the itching from a poison ivy rash can be quite bothersome, the good news is that a poison ivy rash or one caused by poison oak or poison sumac generally isn’t serious. Poison ivy rash treatment consists of self-care methods to relieve itching until the reaction disappears.

Signs and symptoms of a poison ivy rash include:

• Redness
• Itching
• Swelling
• Blisters

Often, the rash looks like a straight line because of the way the plant brushes against the skin. But if you come into contact with a piece of clothing or pet fur that has urushiol on it, the rash may be more spread out.

The reaction usually develops 12 to 48 hours after exposure and can last up to eight weeks. The severity of the rash is dependent on the amount of urushiol that gets on your skin.

In severe cases, new areas of rash may break out several days or more after initial exposure. This may seem like the rash is spreading. But it’s more likely due to the rate at which your skin absorbed the urushiol.

Your skin must come in direct contact with the plant’s oil to be affected. Blister fluid from scratching doesn’t spread the rash, but germs under your fingernails can cause a secondary bacterial infection.

When to see a doctor
See your doctor if any of the following occur:

• The reaction is severe or widespread.
• The rash affects sensitive areas of your body, such as your eyes, mouth or genitals.
• Blisters are oozing pus.
• You develop a fever greater than 100 F (37.8 C).
• The rash doesn’t get better within a few weeks.

Poison ivy, poison oak and poison sumac can all cause contact dermatitis and the resulting itchy rash.

• Poison ivy is an extremely common weed-like plant that may grow as a bush, plant or thick, tree-climbing vine. The leaves typically grow three leaflets to a stem. Some leaves have smooth edges, while others have a jagged, tooth-like appearance. In the fall, the leaves may turn yellow, orange or red. Poison ivy can produce small, greenish flowers and green or off-white berries.
• Poison oak can grow as a low plant or bush, and its leaves resemble oak leaves. Like poison ivy, poison oak typically grows three leaflets to a stem. Poison oak may have yellow-white berries.
• Poison sumac may be a bush or a small tree. It has two rows of leaflets on each stem and a leaflet at the tip.

The irritating substance is the same for each plant, an oily resin called urushiol. When your skin touches the leaves of the plant, it may absorb some of the urushiol made by the plant. Even a small amount of urushiol can cause a reaction. Urushiol is very sticky and doesn’t dry, so it easily attaches to your skin, clothing, tools, equipment or pet’s fur.

You can get a poison ivy reaction from:

• Direct touch. If you directly touch the leaves, stem, roots or berries of the plant, shrub or vine, you may have a reaction.
• Urushiol remaining on your skin. You may develop a poison ivy rash after unknowingly rubbing the urushiol onto other areas of your skin. For example, if you walk through some poison ivy then later touch your shoes, you may get some urushiol on your hands, which you may then transfer to your face by touching or rubbing.
• Urushiol on objects. If you touch urushiol left on an item, such as clothing or firewood, you may have a reaction. Although animals usually aren’t affected by urushiol, if it’s on your pet’s fur and you touch your pet, you may develop a poison ivy rash. Urushiol can remain allergenic for years, especially if kept in a dry environment. So if you put away a contaminated jacket without washing it and take it out a year later, the oil on the jacket may still cause a reaction.
• Inhaling smoke from burning poison ivy, oak or sumac plants. Even the smoke from burned poison ivy, poison oak and poison sumac contains the oil and can irritate or injure your eyes or nasal passages.

A poison ivy rash itself isn’t contagious. Blister fluid doesn’t contain urushiol and won’t spread the rash. In addition, you can’t get poison ivy from another person unless you’ve had contact with urushiol that’s still on that person or on his or her clothing.

Scratching a poison ivy rash with dirty fingernails may cause a secondary bacterial infection. This might cause pus to start oozing from the blisters. See your doctor if this happens. Treatment for a secondary infection generally includes antibiotics.

Contact Dermatitis

from Healthline.com
Definition:

Contact dermatitis is an inflammation of the skin caused by direct contact with an irritating substance.
Alternative Names

Dermatitis – contact; Allergic dermatitis; Dermatitis – allergic; Poison ivy; Poison oak; Poison sumac
Causes, incidence, and risk factors

Contact dermatitis is an inflammation of the skin caused by direct contact with an irritating or allergy-causing substance (irritant or allergen). Reactions may vary in the same person over time. A history of any type of allergies increases the risk for this condition.

Irritant dermatitis, the most common type of contact dermatitis, involves inflammation resulting from contact with acids, alkaline materials such assoaps and detergents, solvents, or other chemicals. The reaction usually resembles a burn.

Allergic contact dermatitis, the second most common type of contact dermatitis, is caused by exposure to a substance or material to which you have become extra sensitive or allergic. The allergic reaction is often delayed, with the rash appearing 24 – 48 hours after exposure. The skin inflammation varies from mild irritation and redness to open sores, depending on the type of irritant, the body part affected, and your sensitivity.

Overtreatment dermatitis is a form of contact dermatitis that occurs when treatment for another skin disorder causes irritation.

Common allergens associated with contact dermatitis include:

* Poison ivy, poison oak, poison sumac
* Other plants
* Nickel or other metals
* Medications
o Antibiotics, especially those applied to the surface of the skin (topical)
o Topical anesthetics
o Other medications
* Rubber or latex
* Cosmetics
* Fabrics and clothing
* Detergents
* Solvents
* Adhesives
* Fragrances, perfumes
* Other chemicals and substances

Contact dermatitis may involve a reaction to a substance that you are exposed to, or use repeatedly. Although there may be no initial reaction, regular use (for example,nail polish remover, preservatives in contact lens solutions, or repeated contact with metals in earring posts and the metal backs of watches) can eventually cause cause sensitivity and reaction to the product.

Some products cause a reaction only when they contact the skin and are exposed to sunlight (photosensitivity). These include shaving lotions, sunscreens, sulfa ointments, some perfumes, coal tar products, and oil from the skin of a lime. A few airborne allergens, such as ragweed or insecticide spray, can cause contact dermatitis.

Symptoms

* Itching (pruritus) of the skin in exposed areas
* Skin redness or inflammation in the exposed area
* Tenderness of the skin in the exposed area
* Localized swelling of the skin
* Warmth of the exposed area (may occur)
* Skin lesion or rash at the site of exposure
o Lesions of any type: redness, rash, papules (pimple-like), vesicles, and bullae (blisters)
o May involve oozing, draining, or crusting
o May become scaly, raw, or thickened

Signs and tests

The diagnosis is primarily based on the skin appearance and a history of exposure to an irritant or an allergen.

According to the American Academy of Allergy, Asthma, and Immunology, “patch testing is the gold standard for contact allergen identification.” Allergy testing with skin patches may isolate the suspected allergen that is causing the reaction.

Patch testing is used for patients who have chronic, recurring contact dermatitis. It requires three office visits and must be done by a clinician with detailed experience in the procedures and interpretation of results. On the first visit, small patches of potential allergens are applied to the skin. These patches are removed 48 hours later to see if a reaction has occurred. A third visit approximately 2 days later is to evaluate for any delayed reaction. You should bring suspected materials with you, especially if you have already tested those materials on a small area of your skin and noticed a reaction.

Other tests may be used to rule out other possible causes, including skin lesion biopsy or culture of the skin lesion (see skin or mucosal biopsy culture).

How can I help my doctor diagnose my skin condition?

Keep a “diary” of when your symptoms appear, get worse or improve. It also helps to write down where your symptoms occur on your body, and how long they last. If you notice that your skin gets worse after certain activities, record the reaction and the activity in as much detail as possible.

Workers in some occupations are more likely to develop allergic contact dermatitis, so it’s important to describe your work to your doctor. If you handle chemicals during the day, make a list of these or find their Material Safety Data Sheets (MSDS).

Treatment

Successful treatment of dermatitis symptoms depends on getting an accurate diagnosis from your physician. Depending on the type of dermatitis and the severity of skin reactions, a physician may prescribe corticosteroids, antifungal agents, antihistamines, barrier creams, and moisturizers for your skin, shampoos with salicylic acid, selenium, zinc, or coal tar, and oral medications. These treatments are intended to treat your symptoms and improve your skin’s condition.

Because there is often no cure for dermatitis, your physician should discuss ways to avoid allergen and/or irritant contact, and how to take better care of your skin. In addition, reducing stress can improve your immune system response and help restore your skin’s normal integrity

Initial treatment includes thorough washing with lots of water to remove any trace of the irritant that may remain on the skin. You should avoid further exposure to known irritants or allergens.

In some cases, the best treatment is to do nothing to the area.

Corticosteroid skin creams or ointments may reduce inflammation. Carefully follow the instructions when using these creams, because overuse, even of low-strength over-the-counter products, may cause a troublesome skin condition. In severe cases,systemic corticosteroids may be needed to reduce inflammation. These are usually tapered gradually over about 12 days to prevent recurrence of the rash.

Contact dermatitis usually clears up without complications within 2 or 3 weeks, but may return if the substance or material that caused it cannot be identified or avoided. A change of occupation or occupational habits may be necessary if the disorder is caused by occupational exposure.
Complications

Secondary bacterial skin infections may occur.

Call your health care provider if symptoms indicate contact dermatitis and it is severe or there is no improvement after treatment.
Prevention

Avoid contact with known allergens. Use protective gloves or other barriers if contact with substances is likely or unavoidable. Wash skin surfaces thoroughly after contact with substances. Avoid overtreating skin disorders.
References

Gober MD, DeCapite TJ, Gaspari AA. Contact dermatitis. In: Adkinson NF Jr, ed. Middleton’s Allergy: Principles and Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 63.

Habif TP. Contact dermatitis and patch testing. In: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 4.