Psoriasis is a condition where the immune system mistakenly signals skin cells to grow at an accelerated rate. This rapid cell turnover leads to the formation of raised, thick, discolored patches known as plaques. When these plaques appear on the scalp, the condition is referred to as scalp psoriasis, affecting up to 80% of people with psoriasis. While scalp psoriasis itself does not directly destroy the hair follicle, the inflammation and scaling interfere with healthy hair growth, leading to noticeable shedding. This relationship involves both the disease’s direct impact and secondary factors like physical trauma.
The Direct Link Between Scalp Psoriasis and Hair Thinning
The primary mechanism linking active scalp psoriasis to hair thinning is the chronic inflammatory response. Psoriatic plaques are areas of intense inflammation and rapid cell buildup, which physically surround and weaken the hair shaft as it emerges from the follicle. This inflammation disrupts the normal, cyclical process of hair growth.
Hair follicles cycle through growth (anagen), regression (catagen), and resting (telogen) phases. Severe inflammation can prematurely force growing hairs into the resting phase, a phenomenon called telogen effluvium. This results in increased hair shedding approximately two to four months after the inflammatory trigger begins.
The thick, silvery scales and plaque buildup associated with severe scalp psoriasis can also mechanically impede the hair shaft. These scales adhere tightly to the hair strands, and their bulk can cause the hair to break or fall out when the scales are disturbed or shed. Fortunately, this type of hair loss is temporary and non-scarring. The hair follicle remains intact and is capable of resuming normal growth once the underlying inflammation is effectively controlled.
Mechanical Stress and External Factors That Worsen Loss
Hair loss is often worsened by external factors and the behaviors a person adopts to manage their symptoms. The intense itching that accompanies scalp psoriasis can lead to excessive scratching, causing physical trauma to the scalp and hair shaft. This action weakens the hair, leading to breakage and dislodging the hair from the follicle.
Picking or forcibly removing the thick, dry scales and plaques is another common behavior that contributes to shedding. Since the scales are often firmly attached to the hair, pulling them off inadvertently rips out hair strands along with them. This trauma further contributes to localized thinning.
Certain topical treatments, while necessary for managing the condition, can also contribute to hair fragility if used improperly. Overusing strong topical steroids can potentially lead to thinning of the skin, making the scalp more susceptible to damage. Harsh topical agents, if left on too long or used too aggressively, can dry out the surrounding skin and hair, increasing the risk of breakage. Gentle handling of the scalp during a flare-up is important for minimizing hair loss.
Managing Scalp Psoriasis and Promoting Hair Regrowth
The primary strategy for halting hair loss and promoting regrowth is to gain control over the underlying scalp inflammation. Since the hair loss is secondary to the psoriasis, successful treatment of the skin condition is the most effective hair restoration method. Treatment plans are highly individualized.
Topical treatments are the first line of defense for mild to moderate cases. These include corticosteroid solutions, which quickly suppress the immune response and reduce redness, and vitamin D analogs, which help regulate skin cell growth. Medicated shampoos containing ingredients like coal tar or salicylic acid are also used to break down the thick scales, making them easier to remove gently without damaging the hair.
For more widespread or stubborn cases, dermatologists may recommend phototherapy using ultraviolet B (UVB) light. This controlled exposure slows the rapid turnover of skin cells and decreases inflammation. Significant clearance may be observed within six to eight weeks of regular phototherapy sessions.
When topical and light therapies are insufficient, systemic or biologic treatments become necessary for severe psoriasis. Systemic medications, such as methotrexate, work internally to suppress the overall immune response. Biologic drugs, administered via injection or infusion, are highly targeted therapies that block specific immune proteins responsible for the inflammatory cascade. Biologics can produce measurable improvements and near-total scalp clearance in a short time frame.
Once the inflammation is successfully managed, the hair follicles can exit the resting phase and return to the active growth cycle. Hair regrowth is probable, but the process takes time. It can take six to twelve months for the affected areas to achieve significant density. Permanent scarring alopecia is a rare outcome, occurring only in extremely chronic, untreated cases where severe, deep inflammation has caused irreparable damage to the follicle structure.