Psoriasis is a chronic condition where the immune system mistakenly triggers inflammation, causing skin cells to multiply up to ten times faster than normal. This rapid turnover leads to the formation of thick, red or discolored patches often covered with silvery scales, known as plaques. Intense itching, medically termed pruritus, affects up to 90% of people with psoriasis. While the urge to scratch is understandable, this simple act of relief can paradoxically worsen the underlying disease.
The Science Behind Scratching and Psoriasis Flares
Scratching definitively makes psoriasis worse due to a biological mechanism called the Koebner phenomenon. This phenomenon describes the appearance of new psoriatic lesions on previously unaffected skin following a physical injury or trauma. Scratching, rubbing, burns, or even a bug bite can trigger this process.
When the skin is damaged, the immune system activates the healing process. In a person with psoriasis, however, this trauma-induced immune response overreacts, leading to the characteristic inflammatory cycle. This reaction causes T-cells and inflammatory molecules to migrate to the injury site, effectively “turning on” the psoriatic process.
For 25% to 30% of people, a new psoriatic plaque will form exactly where the skin was scratched. The new lesions can appear anywhere from a few days to a few weeks after the trauma. This flare-up is an extension of the autoimmune disease, transforming a temporary injury into a persistent psoriatic patch.
Physical and Health Risks of Broken Skin
Beyond triggering the underlying autoimmune response, scratching creates immediate physical damage that compromises the skin’s protective barrier. When skin is aggressively scratched, it can crack, bleed, and develop open wounds. These breaks in the skin serve as entry points for external threats, significantly increasing the risk of secondary bacterial or fungal infections. A secondary infection will cause further pain, redness, and swelling, often requiring antibiotic treatment.
Repeated, long-term scratching also leads to a permanent thickening of the skin, known as lichenification. This thickening occurs as the skin attempts to protect itself from constant friction and can make the area itchier and harder to treat. This heightened inflammatory state prolongs healing time and intensifies the itch sensation, making the desire to scratch even stronger.
Practical Methods to Relieve Psoriasis Itching
Managing the intense itching of psoriasis requires practical strategies focused on soothing the nerves and interrupting the itch-scratch cycle. One effective method is to apply a thick, emollient-rich moisturizer frequently throughout the day. Ointments containing ingredients like petrolatum or glycerin help seal moisture into the skin, reducing dryness and calming the nerve endings responsible for the itch.
The application of cold is another highly effective technique, as the cool temperature temporarily short-circuits the nerve signals that transmit the itch sensation. This can be achieved by placing a cool, damp washcloth or a cold compress on the itchy area for several minutes. Similarly, short, warm baths infused with colloidal oatmeal or Dead Sea salts can help soften scales and soothe irritated skin.
Instead of scratching, individuals can gently pat or rub the area, or immediately apply a moisturizer or an over-the-counter anti-itch cream containing menthol or camphor. For severe nighttime itching that interferes with sleep, a healthcare provider may recommend specific topical medications or oral antihistamines. Maintaining trimmed fingernails and employing distraction techniques, like engaging in a focused activity, can also minimize unconscious skin damage.