Difference Between Poison Ivy and Poison Oak

Poison Ivy vs Poison Oak

Poison ivy and poison oak are the most common causes of allergy. They all belong to the family of Anacardiaceae. Both are in the same genus Toxicodendron. The former species is radicans whereas the species name of poison oak diversilobum.

Contact dermatitis is the allergic condition occurring when certain substances comes into contact with skin.

Though plants like poison ivy are the sources of allergies such as dermatitis, there are other irritants also.

Irritant dermatitis is the most common form of rash in allergies caused by the group of these plants. The allergic responses are a response to the urushiol oil in the plants.

Poison ivy

Poison ivy rashes are quite common in people who like to spend most of the time outside. The rashes are usually reddish and appear like blisters. The allergy is not contagious and the spread can be limited by not using soap. The first-aid involves cleansing the area with alcohol followed by washing in water. Using soap can move the urushiol oil causing the spread and makes it worse. After the first washing with plenty of water, use soap and take a shower.

If you don’t take immediate steps, this will usually settle on your skin and trigger the heavy rashes.

Poison oak

Poison oak is a similar plant causing irritant dermatitis. The plant also has urushiol oil which is the causative agent for allergy.

The plant is found commonly in the western US and Canada. It occurs in both ivy forms and brushy oak like structures. There is another species Toxicodendron pubescens which is commonly called as Atlantic Poison-oak which occurs in Southeastern United States including Texas and Oklahoma states.

The appearance is hairy and the allergen is same urushiol oil which is most potent irritant among those derived from plants.

Difference between Poison Ivy and Poison Oak


Both of them belong to the same family and same genus differing in the species. The poison oak leaves resemble the leaves of oak tree and hence the name.


Three leaflets, hairy surface, white berries are characteristics of poison ivy. Poison oak leaves are similar but resemble oak tree leaves.


The poison ivy grows as bush, shrub or vine whereas poison oak grows as a shrub in most cases although a few vine forms are prevalent.


Poison ivy plants are common in the western half of US. Poison oak is found in the eastern side particularly along the coast of Mississippi.


The first aid for all rashes is same. For the rashes by poison ivy and poison oak, further treatment is done with calamine lotion and prednisone.


Both are not contagious if the urushiol oil is not spread by chance. Infections can rarely result from itching

Both plants appear similar, produce the same kind of rash and require the same treatment. It depends on where you are residing in to differentiate a poison ivy rash from poison oak rash. The resin urushiol is the causative agent of contact dermatitis. The best way to prevent such rashes is avoiding exposure to them.