How Does UVB Therapy Work?

by | Oct 5, 2023

Ultraviolet B (UVB) phototherapy delivers shortwave ultraviolet radiation to treat skin conditions such as psoriasis. Phototherapy works by suppressing DNA synthesis, which in turn reduces inflammation.

Narrowband UVB phototherapy (311–312 nm) is increasingly used compared to broadband UVB phototherapy (270–350 nm). This is because exposure and treatment times are shorter and result in longer periods of remission. Here at Skin Matters Bristol, we use wavelengths between 311-312 nm.


How is UVB phototherapy delivered?

UVB phototherapy is delivered within a specially designed cabinet or handheld device, depending on the severity of your condition. Fluorescent light tubes are positioned to target affected areas with ultraviolet radiation (eg, hands or feet). For full body treatments, patients need to protect their eyes or full face with goggles or a face mask.

Most patients will have treatment three times a week, at least 24 hours apart. Session length is initially 5 minutes, and may be uptitrated as required to a maximum of 30 minutes per session. The number and length of sessions vary for each individual, taking into account their skin type, skin condition, and previous response to treatment. We can give you advice on this.

Phototesting to determine the minimum dose that produces skin redness (MED testing) is recommended and a starting dose of 70% of the MED is often used.  The dose is escalated by 20% each treatment, provided there are no side effects or episodes of burning.

Targeted phototherapy devices (eg, excimer laser, brush or comb devices) have also been developed as treatment options for more challenging areas while sparing uninvolved skin.



Psoriasis is a chronic inflammatory skin disorder, which varies considerably in extent and severity. UVB is suitable for most people with extensive psoriasis. It may not suit those with very fair skin or those whose psoriasis gets worse in sunlight.

Most patients will have clearance or improvement in their psoriasis after 12 to 24 treatments. After treatment is discontinued the skin may remain clear for months. If psoriasis flares up again, further UVB treatment may be necessary. Here are some of the products we have available in our online store.

Handheld UV308E1 UVB Unit

Handheld UV308B1 UVB Unit

Handheld UVB Narrowband



UVB is occasionally used for severe cases of dermatitis, especially atopic dermatitis (eczema). Frequency and dosage of treatment are usually longer than for psoriasis.



UVB is effective in treating vitiligo by immune suppression and stimulation of cytokines. Treatment is given twice a week for 3–4 months and continued until re-pigmentation is complete or for 1–2 years. It may take several months to see an improvement and caution must be taken with fair skin.


What are the benefits of UVB phototherapy?

  • Can be used to treat the whole body or localised areas.
  • Narrowband UVB phototherapy is less likely to cause cancer than PUVA (photochemotherapy) as there is less UV exposure and a narrower range of UV radiation.
  • In some places, home phototherapy may be offered.
  • Safer and often cheaper alternative to systemic therapy.


Phototherapy using UVB light is rarely used in the UK because of limited availability and the number of hospital visits required (the backlog with the NHS can leave you waiting a long time). But a study of 200 patients found the same results with home treatment.

One UK expert said the British Medical Journal study highlighted an important treatment gap in psoriasis care. In this area of work, there are very large numbers of people who don’t have access to phototherapy, which is a shame as it’s a very effective and safe treatment. Especially in built up areas such as Cheltenham, Bristol and Gloucester, finding hospital bookings can be hard to come by. Psoriasis light treatment is the solution for you.

Gladys Edwards, chief executive of the Psoriasis Association, said “the guidelines on treating psoriasis should be reviewed in light of the new research. Patient choice is important and for some patients managing their UV treatment at home would clearly be preferable. It is crucial, however, that there is absolutely clear guidance and information on when this is appropriate and how it should be managed for patients and doctors alike.”

This is why we offer home treatments, as this is available for you to use 24/7 for the duration of your hire, or if you buy the appliance completely. This takes away the struggle of balancing appointments with doctors or experimenting with other methods such as using sunbeds. Sunbed skin damage is a real factor as to why you should NEVER use these as a skin remedy source.

Make sure to contact us for more information on our UVB products available in stock.