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We’ve all heard of poison ivy. Many people have an allergic reaction, also known as contact dermatitis, after contact with poison ivy plants. Poison sumac and poison oak cause the same reaction. The resin of all three plants contains an oily substance called urushiol, which is responsible for allergic reactions. Poison ivy, poison oak, and poison sumac are the most common cause of allergic reactions in the United States. The American Academy of Dermatology states that up to 50 million urushiol-induced allergic reactions occur every year.
Most dermatologists are very familiar with urushiol reactions because the causative plants grow all over the country, including Southlake, TX. Poison oak is more common than poison ivy in the western and southern parts of the country, but this is a relative comparison. There is no shortage of poison ivy in Texas. The roots, stems, and leaves of these plants contain resin, commonly known as sap, which means contact with any part can trigger a reaction. Sap is colorless or pale yellow with an oily, and very sticky, consistency.
Exposure and Allergic Reaction
Urushiol is present on the surface of intact plants, but much more of the oil is released when plants are crushed or damaged. Damaged plants may have black spots because urushiol turns black after exposure to air. Never burn poison ivy, poison oak, or sumac. Airborne urushiol particles from burning plants create an inhalation risk. A potentially life-threatening allergic reaction can occur in the trachea or lungs.
An allergic reaction to urushiol doesn’t usually result in rash immediately. Reactions generally occur within 12-21 days after the first exposure, but the rash appears only 12-72 hours after repeated exposures. This type of allergy is described as delayed-type hypersensitivity.
Allergic reactions vary between individuals, depending on sensitivity and strength of immune responses. Approximately 15% to 30% of people are not allergic to urushiol, so they don’t develop a rash or any other symptoms after exposure. On the other hand, approximately 25% of the population can experience a severe allergic reaction.
Common signs and symptoms of a reaction to urushiol include:
- Intense itching
- red, swollen lines on the skin with streaks or patches
- small, fluid-filled red bumps
No one can ‘catch’ a rash or any other symptoms of an allergic reaction from another person. It may seem like the rash can spread to other parts of the body, but this is a misleading impression. Urushiol may penetrate thick or calloused skin at a slower rate, so a rash develops a little later. Talk to your dermatologist if new rashes appear and you aren’t sure of the source.
The most likely cause of new rashes on different parts of the body is fresh contact with urushiol oil that is still present somewhere. The sticky oil is easily transferred from one surface to another. Plant resin sticks to skin, clothing, tools, and even animal fur. Urushiol is an impressive, if extremely irritating, substance. It can stay active for over a year.
There is no cure for a rash caused by poison ivy. Prevention is the best treatment. Anyone that spends a lot of time outdoors in Southlake, TX, should learn to identify potentially toxic plants. ‘Outdoors’ doesn’t just refer to camping or hiking. Poison ivy and poison oak can grow in an average backyard. Poison sumac could grow in a person’s yard, but trees are more noticeable than plants that blend into undergrowth or bushes. All three plants produce resin all year round, whether leaves are present or not.
Sometimes a rash can be prevented after contact with poison ivy. Remove oils from your skin immediately after contact with the plant. Ordinary soap is fine for washing exposed skin, but be careful with bar soaps.
Rinse your skin with lukewarm water before using a soap bar so the oil won’t stick to the bar and spread to other parts of your body. Use caution with wash cloths, sponges and loofahs that may pick up oil from your skin. Wash these items thoroughly or dispose of them immediately after bathing to make sure the oil won’t spread.
Alcohol wipes work when you don’t have immediate access to a shower or soap and water. Wash all exposed areas three times to make sure the sticky resin is gone. Even a tiny amount of urushiol may trigger a reaction.
Dermatologists recommend washing clothes, shoes and anything else you were wearing or carrying after contact with poison ivy. The same advice applies to poison oak or poison sumac. Regular laundry detergent removes urushiol from most clothing, but it isn’t effective for suede or leather. Bleach deactivates the oil on clothing and most surfaces.
Most cases of poison ivy reactions don’t require a visit to a dermatologist. Leave blisters intact to heal on their own, even if they begin oozing or form a crust. Breaking blisters creates a very inviting entry point for bacteria that cause infection.
Unmedicated hand lotion, ice, and cold water aren’t effective against an allergic rash, but cooling the rash and surrounding skin might reduce inflammation and swelling. Most reactions heal within 10 to 14 days.
You can always visit a dermatologist for help. Burning and itching aren’t pleasant, and a dermatologist can help you manage symptoms. Dermatologists may recommend over-the-counter creams and baking soda or oatmeal baths. Other options include oral medications to counteract severe itching and steroid creams or injections to relieving itching, swelling, and inflammation.
Severe allergic reactions or an accompanying fever above 100 degrees F do require medical help. Always consult a dermatologist if bumps or blisters contain white, yellow or thick fluid that indicate infection. Untreated infected rashes can leave scars and may cause a systemic infection.
Contact Compassion Dermatology if you have a urushiol-induced rash. Sometimes we can brush up against a toxic plant or encounter sticky resin without realizing it. A dermatologist can help if you aren’t sure what caused a rash.