There are many different types of psoriasis and associated conditions, though some are rarer than others.
The most common form of psoriasis, named plaque psoriasis (psoriasis vulgaris), occurs in 90% of people with psoriasis
Plaque psoriasis involves red, inflamed ‘plaques’ or patches of skin which can be scaly, itchy and painful. If you have this form of psoriasis, you may only have a few, spaced out plaques, or they may form together into larger plaques. These plaques are an irregular round or oval shape and most commonly form on the scalp, trunk, buttocks and limbs, and especially areas around the joints, such as elbows and knees.
Psoriasis can cause changes to the nails, such as pitting (deep to shallow holes) or ridges (lines running from the nail bed to the end), crumbling, loss of nails, and the ‘oil drop sign’ – a salmon pink discoloration of the nail bed.
Damaged and inflamed areas form in folds of the skin, like around the buttocks, genitals, armpits or beneath the breasts. These are typically sensitive areas, which can be worsened due to sweat and friction.
Psoriatic arthritis is a type of arthritis that can develop in some people with psoriasis, where joints may become stiff, swollen, tender and painful - though not everyone with psoriatic arthritis has been affected by psoriasis and the related skin symptoms.
Cells from the immune system collect in the top layer of skin due to inflammation. This can cause pustules to form. Pustules are bumps on the skin filled with fluid, which can be in one or a small number of areas (often on the hands and feet), or across the whole body. They are not contagious.
Drop shaped swellings form. These drops are red, scaly, small, and not as thick as the ‘plaques’ that form in plaque psoriasis, though they may cluster together. If you have these drops, they could be the first sign of psoriasis, or occur alongside plaques. They can be triggered by bacterial infections, including throat infections, tonsillitis, and the common cold. Guttate psoriasis usually clears within a few months with minor or no treatment, though it may progress to chronic plaque psoriasis. It is most common in younger people under 30 years-old.
Redness and scaling form all over the body. It is a severe form of psoriasis. If you have reddened skin everywhere, this can change the way the skin manages temperature, leading to chills, dangerously low body temperature (hypothermia), fluid loss and dehydration.