These are all very similar and it can be tricky to tell the difference between them in certain cases. Eczema causes severe inflammation in the skin, often presenting as a red, itchy rash and sometimes as small blisters. It is more common in children under 5 but the condition can flare up at any time, anywhere on the body.
Psoriasis sufferers develop red, flaky or crusty dry patches which are often covered with silvery scales. It is caused by the body producing too many new skin cells too quickly. These older cells build up on the skin and cause inflammation and flaky patches. Psoriasis alters the way skin cells are made, while eczema mainly increases their sensitivity to the environment.
Dermatitis is the term used to describe any skin inflammation and covers several different types ranging from eczema to dandruff. If the skin is swollen, red and itchy it is likely that your skin has some form of dermatitis. If you are still unsure, visit your GP for more information.