Psoriasis is caused by an overactive immune system that mistakenly attacks healthy skin cells, leading to rapid skin cell production and inflammation. Normally, skin cells take about 3 to 4 weeks to mature and shed, but in psoriasis, this process accelerates to just 3 to 7 days, causing a buildup of immature skin cells that form scaly patches

. The exact cause of this immune system dysfunction is not fully understood, but both genetic and environmental factors play key roles. Psoriasis tends to run in families, suggesting a genetic predisposition involving multiple genes that affect immune function and skin cell behavior. Specific genes linked to psoriasis include those in the PSORS1 locus (such as HLA-Cw6) and genes related to immune signaling like IL12B and IL23R

. Environmental triggers can provoke or worsen psoriasis in genetically susceptible individuals. Common triggers include:

• Skin injury (cuts, scrapes, insect bites, sunburn)
• Infections, especially streptococcal throat infections
• Stress
• Certain medications (lithium, some blood pressure drugs, antimalarials)
• Cold, dry weather
• Smoking and heavy alcohol consumption
• Hormonal changes (e.g., puberty, menopause)

In summary, psoriasis results from a complex interplay of immune system malfunction, genetic susceptibility, and environmental triggers that cause skin cells to grow too quickly and inflame the skin