A full history and physical examination are needed to diagnose Contact Dermatitis and to determine whether it is Allergic or Irritant. For determining and knowing the cause of allergic contact dermatitis, a technique called “patch testing” might be useful. A series of exposures are needed to manifest that the person has allergic reaction to a particular substance. In this case, Allergic contact dermatitis is more challenging to diagnose than Irritant Contact Dermatitis. Dermatitis caused by plants may be easy to confirm because of the pattern it makes to the affected skin. It usually appears as a linear eruption because the affected skin moves past the leaves of the plant in a line, distributing the allergenic material linearly.
Getting rid of the cause would be the best treatment. If you know what causes your rash, better avoid contact with the substance again. For easing the discomfort, a hydrocortisone cream may be used to cover a small affected area. Washing your skin with mild soap and cool water right away may also help in treating the symptoms.
Avoidance of the substance that causes contact dermatitis is all you need. However, if contact with these particular substances would be inevitable, you can try some precautionary methods such as wearing of protective clothing or applying barrier creams.