How Severe Is Your Psoriasis?

Medically Reviewed by Debra Jaliman, MD on February 29, 2024
3 min read

If you’re wondering whether you have mild, moderate, or severe psoriasis, think about these three things:

Body surface area: How much of your body has psoriasis? To figure this out, keep in mind that generally, your hand is equal to 1%.

Severity: What's the average scaling, thickness, and redness of your lesions? The more you have, the more severe your condition is.

Quality of life (QOL): How much does your psoriasis affect your daily life? Tools that measure this include questions about your condition, your skin, emotions, and relationships.

Severity and body surface area are used together to calculate something called a Psoriasis Area and Severity Index (PASI) score. It combines the severity and surface area for six regions of your body. Scores range from 0 to 72. A score of more than 10 generally translates to “moderate-to-severe.” A score of more than 40 is rare.

Usually, the higher your PASI score, the lower your quality of life.

Your doctor may use one of three surveys to figure out how your psoriasis affects your quality of life:

Psoriasis Index of Quality of Life (PSORIQoL): This tool focuses on how psoriasis changes how you deal with the needs of daily life. Questions cover things like sleep, your social life, and emotions.

Psoriasis Life Stress Inventory (PLSI): It's a 15-item questionnaire that asks you how stressful various daily tasks are for you.

Psoriasis Disability Index (PDI): The PDI looks at how psoriasis affects your daily activities, including work, leisure time, and personal relationships.

In general, mild psoriasis means less than 3% of your body is affected. This typically means you have isolated patches on your limbs and on your scalp. Psoriasis is also considered mild if a skin medication controls it or if it only affects your quality of life a little bit.

Moderate psoriasis is when 3% to 10% of your body has patches. This usually means it affects your arms and legs, torso, and scalp. It's also considered moderate if it can’t be controlled using a skin medication or if it has a significant impact on your quality of life.

If more than 10% of your body is affected, or if large areas on your face, palms or soles of your feet have patches, you have severe psoriasis. It can also be deemed severe if it is in places that are constantly irritated, such as folds of the skin, it can’t be controlled using a skin medication, or it has a serious impact on your quality of life. 

Knowing whether your psoriasis is mild, moderate, or severe will help you find the best treatment. It'll also let your doctor know whether the psoriasis is getting worse and how well your treatment is working.

Your doctor may use the PASI score to measure your progress. For example, if you hear you’re "PASI 75," that means your PASI score has dropped by 75%.