Atopic dermatitis occurs when you scratch your skin when it starts to itch. When you start scratching the skin can crack leaving openings for the germs to get into your skin.
Once germs get in through the cracks, they cause skin inflammation. Once you start scratching, the tendency to scratch more increases and further damages the skin.
Urticaria is a type of atopic dermatitis that lasts only for a short while and disappears. They appear in a cluster of small red bumps. Sometimes the lips, eyes, hands or feet might swell up. This is called angioedema.
Contact Dermatitis occurs when you come in contact with an allergic substance. Your skin can be allergic to ingredients in cosmetics, detergents, body soap, metals used in jewelry etc.
In this case, the part of the skin which comes in contact with the allergic substance start to itch.
When your skin comes in contact with Poison Ivy, your skin starts to itch, and blisters appear on the skin. This is an example of "Contact Dermatitis."
Your skin can itch without any rash or outward symptoms. This can be due to an internal disease. For example, when you have diabetes, your skin can begin to itch when the sugar level in your blood increases.
There are many treatments available for curing allergies of the skin. Consult a dermatologist and do not self-treat the condition. This might make matters worse.
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