Light Therapy for Psoriasis: How It Works and What Else Helps
From UV phototherapy to vitamin D and injections, here's how psoriasis treatment has expanded beyond creams.
Key takeaways
- Phototherapy (UVB light) is a well-established, prescription-supervised treatment for moderate psoriasis.
- Red light therapy has some early evidence for skin inflammation but is less studied than UVB for psoriasis specifically.
- Low vitamin D is common in people with psoriasis, and topical vitamin D analogues are a standard treatment.
- Biologic injections are reserved for moderate-to-severe psoriasis not controlled by topical treatment or light therapy.
When creams and shampoos aren't enough to control psoriasis, dermatologists often turn to light-based treatments or systemic medication. Here's how the main options work.
How does light therapy for psoriasis work?
Medical phototherapy uses controlled doses of ultraviolet B (UVB) light, administered in a clinic or with a home unit prescribed by a dermatologist, to slow the overactive skin cell turnover that drives psoriasis plaques. Treatment is typically given two to three times a week for several weeks, with the dose carefully increased to avoid burning.
What about red light therapy?
Red light therapy (low-level light therapy) uses visible red or near-infrared light rather than UVB, and is marketed for various skin concerns including inflammation and wound healing. There's less direct clinical evidence for red light therapy specifically in psoriasis compared with established UVB phototherapy, so it's generally considered an adjunct or unproven option rather than a replacement for medically supervised phototherapy.
Vitamin D and psoriasis
Many people with psoriasis have lower vitamin D levels, and UVB exposure itself boosts vitamin D synthesis in skin. Topical vitamin D analogues (like calcipotriene) are a standard prescription treatment that slows skin cell growth, often combined with a topical steroid. Oral vitamin D supplementation for psoriasis specifically hasn't shown the same strong evidence as topical analogues, though correcting a true deficiency is reasonable for general health.
When are injections used?
- Biologic injections (e.g., targeting TNF-alpha, IL-17 or IL-23) — used for moderate-to-severe psoriasis not controlled by topical treatment.
- Methotrexate or other systemic medications — an alternative or add-on for widespread disease.
- Injections are typically started under a dermatologist's supervision, with monitoring for side effects.
Where natural options fit in
Compounds in black seed oil have shown anti-inflammatory activity in lab studies relevant to psoriasis-type inflammation,[1] but they are not a substitute for phototherapy or prescribed systemic treatment in moderate-to-severe disease. They may be used as a gentle adjunct for scalp or mild plaque care — see our scalp psoriasis guide.
When to see a doctor
Black seed oil and oregano oil are not a substitute for diagnosis or prescribed treatment. See a healthcare professional if symptoms are severe, getting worse or not improving.
Frequently asked questions
How many phototherapy sessions does psoriasis need before improving?
Many people see improvement after several weeks of consistent sessions (often 2–3 times weekly), though timelines vary by individual.
Is red light therapy proven for psoriasis?
Not to the same degree as UVB phototherapy — more research is needed before it can be considered an established psoriasis treatment.
Do psoriasis injections work quickly?
Biologics often show noticeable improvement within weeks, though full effect may take a few months.
The bottom line
Light-based and systemic treatments have transformed care for moderate-to-severe psoriasis, with UVB phototherapy and biologic injections offering the strongest evidence. Vitamin D and natural anti-inflammatories may offer supportive benefits but work best alongside — not instead of — these treatments.
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