Physical urticaria

Five minutes following physical contact, the skin produces a weal that will last 15–30 minutes. Some people experience just the physical type of urticaria and others have it in combination with a more chronic type. The cause is unknown.

This literally describes skin writing and the individual experiences weals wherever the skin is touched be this through stroking the skin, touching it on furniture or the gentle pressure of clothes. The weals are usually itchy and aggravated when scratched, they can be worse when the individual is warm or upset.

Thermal
Certain temperature ranges can cause urticarial reactions. For example cholinergic describes the tiny red dots that appear on the skin following sweating, these can be very itchy. Cold contact urticaria usually strikes when cold skin is warming up after being exposed to cold outdoor temperatures. When the weals are widespread it can cause fainting attacks. Localised heat and solar urticaria are less common but describe the development of weals following exposure to said stimuli. Contact urticaria
This is caused by physical contact either through the skin or mucous membranes, with a substance leading to either an allergic or non- allergic response. An IgE elicited response may be caused by a range of substances including white flour, latex, cosmetics or fish. A non- allergic reaction is caused by contact with substances such as nettles, certain insects (e.g. a hairy caterpillar). Weals may be limited to the contact area or may become more widespread.