Is Psoriasis Vulgaris Infectious?
No, psoriasis vulgaris is absolutely not infectious or contagious—it cannot be transmitted from person to person through any form of contact.
What Psoriasis Actually Is
Psoriasis vulgaris is a chronic inflammatory, immune-mediated skin disease, not an infection 1, 2. The condition results from:
- Inappropriate activation of cutaneous T cells and dendritic cells
- Release of inflammatory cytokines and soluble mediators
- Keratinocyte hyperproliferation that creates the characteristic red plaques with silvery scale
This is an autoimmune/autoinflammatory process, not a communicable disease.
The Confusion: Infections as Triggers vs. Being Infectious
A critical distinction must be made—while psoriasis itself is not infectious, infections can trigger or worsen psoriasis in susceptible individuals 3, 4:
Common Infectious Triggers Include:
- Streptococcal infections (particularly associated with guttate psoriasis onset)
- Staphylococcal infections
- Viral infections (HIV, hepatitis C, HPV)
- Fungal infections (Candida, Malassezia species) 5
- Tuberculosis (can trigger disease onset) 6
These pathogens act as environmental triggers in genetically predisposed individuals by:
- Acting as superantigens that activate skin-seeking T cells
- Producing inflammatory cytokines that induce or aggravate psoriatic lesions
- Disrupting the skin microbiome balance
Clinical Implications
For patient counseling:
- Reassure patients emphatically that they cannot spread psoriasis to others
- Physical contact, sharing personal items, or proximity poses zero transmission risk
- The visible nature of lesions often causes social stigma based on this misconception
For clinical management:
- Screen for and treat concurrent infections that may be exacerbating disease 7
- Consider tuberculosis screening before initiating biologic therapies
- Address skin microbiome disruption as part of comprehensive management 3
Common Pitfall to Avoid
Do not confuse "infection-provoked" with "infectious." The fact that infections can trigger psoriasis flares does not make psoriasis itself contagious—this is a fundamental misunderstanding that causes significant psychosocial distress for patients.