Psoriasis is usually a long-term problem. Symptoms tend to come and go in a cycle of flares, when symptoms get worse, and remission, when symptoms improve and go away for awhile. In other cases psoriasis may persist for long periods of time without getting better or worse.

Several things can make symptoms worse, depending on the type of psoriasis. These factors, or triggers, include:

• Cold.
• Dry climates.
• Stress.
• Infection.
• Skin injury.
• Certain medicines.

A few cases of psoriasis may go away without treatment. But it's usually best to treat psoriasis so that it doesn't get worse. If it becomes severe and widespread, it may be much harder to treat.

Mild, moderate, and severe psoriasis

The severity of psoriasis is indicated by the amount of redness and scaling, the thickness of the large areas of raised skin patches (plaques), and the percentage of your skin that is affected.

Mild

• Plaques cover a small portion of the body, such as the elbows or knees.

Moderate

• Plaques cover several large areas. For example, most of the scalp may be affected.
• Plaques may cover up to 20% of the skin (about equal to having both arms completely covered).
• Any joint pain is mild, but not disabling.
• Plaques tend to be visible to other people.

Severe

When severe, psoriasis can be:

• On the face.
• Plaques that may cover large areas (20% to 30%) of the body. When determining the percent of coverage, consider that the palm of your hand equals about 1% of your body surface, and the total surface of both arms equals about 20%.
• Pustular psoriasis with large, fluid-filled plaque and severe scaling.
• Erythrodermic psoriasis with severe inflammation and shedding (sloughing) of the skin.
• Psoriatic arthritis, which includes ongoing joint swelling, tenderness, limitation of range of motion, or joint warmth or redness. Severe cases can result in joint destruction.

Learn more about the different types of psoriasis.