What is Urushiol?

Urushiol is a mixture of organic compounds which has properties of an irritant. The mixture is oily in nature and is found in the plants belonging to the family of Anacardiaceae. The exact composition of the mixture depending on the plant source. Some of the members of family Anacardiaceae are: Cashew, poison ivy and Asiatic lacquer tree etc.

The name urushiol comes from the Japanese word for the lacquer tree – “Urushi”

Urushiol structure:

(Image source: Wikipedia)

Where R can be an unsaturated alkyl chain whose length can be from 15 to 17 carbons.

Example: (CH2)7CH=CHCH2CH=CHCH2CH=CH2

Where is urushiol present in plant?

The location of urushiol in plant varies across species. In mango it is present on the skin of the fruit, in cashew it is found on the surface of the outer shell, but in case of Asiatic lacquer tree it is present in sap of the tree which is extracted by cutting 5-10 lines on the trunk. In poison ivy it can be found in the leaves, stem, fruits roots and the sap of the plant.

Allergic Response:

Coming into contact with urushiol usually causes rashes, itching and blisters. Once exposed the allergic reaction continues for roughly 2 weeks and medications exist to reduce the severity of the symptoms. It is to be noted that the allergen can stay on cloths for over a week in a dry environment.

Treatment:

It takes 10-20 minutes for urushiol to penetrate the skin and bind with the proteins present in the skin. It can be removed before it penetrates the skin by using generous amounts of soap and water. It is also recommended that one clean their clothes thoroughly once exposed to urushiol.

Calamine (a combination of zinc oxide and ferric oxide- Example: DERMOCALM) and oatmeal baths are recommended for symptomatic relief. For severe cases anti histamines such as ALLEGRA-M can provide relief.

For the pain caused analgesics and Non-steroidal Anti-inflammatory drugs are also given.

Systemic steroids and high potency steroidal creams are used for severe cases.

Consult a doctor immediately after exposure to Urushiol.

Mechanism of action:

Urushiol itself is too small to cause any reaction from the body, therefore it attaches itself to certain proteins which are present in the skin. By doing this it acts as a hapten (Hapten is a small molecule which when combined with a larger molecule/ carrier such as protein can act as an antigen) leading to hypersensitive reaction.