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
