-Rash appears in areas on the body that came in contact with the poison ivy.

-Rash appears:

-red, swollen, and with small

hive-like bumps

-extremely itchy

-fluid-filled

-scaly or peeling

-The area around the rash may be painful or tender to the touch. Swelling around the rash may also be present.

-If the irritant is avoided, the rash usually resolves in 2-4 weeks.

-Be aware of what poison ivy looks like and where it can be found outdoors.

-Wear protective clothing (ex. long sleeves/pants) to prevent contact with the irritant.

-Use of OTC anti-itch creams, antihistamines, and/or corticosteroids can help with the management of the rash.

-Call 911 if signs of troubled breathing occur as this could be a sign of anaphylaxis. A shot of epinephrine can counteract the reaction.

• CD4+ T-Cells

• CD8+ T-Cells

No antibodies are considered a primary mechanism in contact dermatitis.

Haptens (for example: Urushiol from poison ivy plants bonded to proteins) penetrate the skin. That complex is then taken to the nearby lymph nodes by dendritic cells to T lymphocytes. As a response, CD4+ and CD8+ T cells are activated and proliferate creating a pool of T-Cells that are specific to the antigen. This inflammatory response is essentially stored and will occur with subsequent exposure.

Contact dermatitis formed from contact with poison ivy is a result of an allergic reaction to urushiol, an oil of the poison ivy plant. This oil can be found in the stems, roots and leaves of the poison ivy plant. The reaction to urushiol exposure takes several hours to days to take effect and can be worsened by transferring the oil via touch to other areas of the body. The more urushiol oil one is exposed to has a direct impact on the severity of the reaction. 

Contact dermatitis can be formed from other exposures as well such as that with metal ions or chemicals. While contact dermatitis is not contagious, it is a very unpleasant condition that can often take two to four weeks to fully clear up.

The above picture shows how the skin reacts in a type four sensitivity reaction to poison ivy. The urushiol oil in the plant is an allergen. Typically the first contact with this oil, will result in a reactive T cell recognition of the allergen. It is after the second exposure, as seen above, where the body will react to the allergen resulting in contact dermatitis.

Monica Glowacki

Izabella Tedesco

• Delayed Response (24-72 Hours)

• Cell Mediated (T-Lymphocytes)

Cleveland Clinic. (2024, May 1). https://my.clevelandclinic.org/health/diseases/6173-contact-dermatitis 

Litchman, G., Nair, P., Atwater, A., & Bhutta, B. (2023, September 4). Contact dermatitis. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK459230/

López CB;Kalergis AM;Becker MI;Garbarino JA;De Ioannes AE; (n.d.). Cd8+ T cells   are the effectors of the contact dermatitis induced by urushiol in mice and are regulated by CD4+ T cells. International archives of allergy and immunology. https://pubmed.ncbi.nlm.nih.gov/9831807/

Marwa, K. (2023, August 12). Type IV hypersensitivity reaction. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK562228/

Mayo Foundation for Medical Education and Research. (2024, May 2). Contact dermatitis. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/contact-dermatitis/symptoms-causes/syc-20352742

Murphy, P. B. (2023, July 13). Allergic contact dermatitis. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK532866/ 

Rogers, J. (2022). McCance & Heuther’s Pathophysiology: The Biology Basics for Disease in Adults and Children (9th ed.). Elsevier.