Urticaria and/or angioedema can be caused by things around us, like a change in temperature, something pressing on the skin, or even vibration. Two rare but serious causes of hives are being exposed to sunlight and touching water.
Cold-dependent Disorders
Cold urticaria is caused by being in cold weathers (e.g. rainy, snowy, windy) in a cold environment (e.g. after swimming) and while holding cold objects (e.g. cold glass of juice). It usually only affects the skin that was exposed to the cold. A small test can be done by placing an ice-cube on the arm for four to five minutes. If it is cold urticaria, the rash will appear there in the shape of the ice-cube a few minutes later.
Cold-dependent dermatographism is a condition where hives form when the skin is scratched and then chilled. It affects four to five percent of the population. It’s usually less pruritic than other causes of urticaria.
Cholinergic or Generalized Heat Urticaria
This manifests as small wheals surrounded by a large area of redness that appears after or during exercise, hot showers, sweating and anxiety. The rash starts on the neck and chest along with severe itching. It spreads slowly to the face, back, arms and legs. The wheals get bigger. Sometimes, they come together and look like angioedema. It could be associated with watery eyes, drooling and diarrhea all together. This is the only type of hives that can be caused by a change in your emotions.
Exercise-induced anaphylaxis is when itching, skin rash, swelling, wheezing and low blood pressure occur after or during exercise. The hives seen with exercise-induced anaphylaxis are large in size. Exercising should be stopped at the start of any symptoms.
Pressure-induced Urticaria/Angioedema
Pressure-induced urticaria/angioedema happens four to six hours after constant pressing on the skin. There may be either a rash or swelling, or both on skin areas covered by tight clothing, on feet and hands after using them for a long time (e.g. hammering, walking), and on the buttocks after sitting for long hours. Pressure-induced urticaria is commonly seen in patients with chronic urticaria.
Solar Urticaria/Angioedema
This is a rare disorder. Itching and redness occur in the first few minutes (one to three minutes) after being out on sunlight. Redness and swelling can happen on the parts of your body not covered by clothes. It usually goes away within three hours.
Aquagenic Urticaria/Angioedema
This is a rare kind of urticaria that some people can get after contact with water.
