UVB Info

Most psoriasis sufferers benefit from exposure to UVB light, one of the forms of ultra violet light that comes from the sun. There are 3 forms: UVA, UVB and UVC. Short wavelength UVC is absorbed by the ozone layer and does not reach the earth’s surface. The UV light which does reach us is mainly long wave UVA, with some intermediate UVB and it is the UVB rays which are beneficial to those of us with psoriasis. UV light aids chemical reactions that affect the function of cells. In psoriasis this means that the cells do not multiply so rapidly and behave more like normal skin.

Too much UVB however is not a good thing because it burns. UVA is also not harmless and too much of both can prematurely age the skin and increase the risk of skin cancers. So you do need to take care even if you find that the sun helps your skin. The people at highest risk are those who have fair or red hair and those whose skin does not tan easily.


What is UVB Treatment?

UVB treatment can be used for a number of skin conditions such as psoriasis, vitamin D deficiency, eczema, vitiligo, acne and scleroderma. Even though we specifically mention psoriasis our notes apply to all these conditions and some other skin conditions that react positively to UVB light. If in doubt please consult your doctor or dermatologist.


UVB contains a wide range of wavelengths and can be used to treat guttate or plaque psoriasis (plus acne and eczema), which is proving resistant to “topical” treatments (i.e. creams and ointments). In the past few years a more refined form of UVB has been developed, known as “narrowband” and this is proving to be very effective. Narrowband is proved to be more readily absorbed into the skin and therefore is generally more effective than traditional broadband UVB treatments. Scientists have established that UVB at a certain wavelength (311nm) is particularly theraputic for skin conditions.

The aim is to clear the skin and this can take up to 30 treatments over a period of approx 6 weeks depending on the severity of the condition.

Compared with broadband UVB in the treatment of psoriasis:

  • Exposure times are shorter but of higher intensity. 
  • The course of treatment is shorter.
  • It is more likely to clear the psoriasis.
  • Longer periods of remission can occur before the psoriasis reappears. 

Another common ailment, but completely different to psoriasis, is vitamin D deficiency. Our main source of vitamin D is that made by our own bodies. 90% of our vitamin D is made in the skin with the help of sunlight.

UVB sunlight rays convert cholesterol in the skin into vitamin D. Darker skins need more sun to get the same amount of vitamin D as a fair-skinned person. The sunlight needed has to fall directly on to bare skin (through a window is not enough). 2-3 exposures of sunlight per week in the summer months (April to September) are enough for normal people to achieve healthy vitamin D levels that last through the year. Each episode should be 20-30 minutes to bare arms and face. This is not the same as suntanning; the skin simply needs to be exposed to sunlight.

For some people this is not enough and UVB narrowband treatment is excellent for increasing Vitamin D levels within the body. Again this must be applied directly onto bare skin but with the narrowband treatment this should be for 30 seconds up to 2 minutes per session.

Side effects

Narrow-band UVB can result in burning, just like sunlight and broadband UVB. Frequent emollients should be applied to burned skin, and if recommended by the therapist, topical steroids. It sometimes provokes polymorphous light eruption. Long term exposure to ultraviolet radiation ultimately causes skin ageing and skin cancers. If used sensibly Narrowband is certainly less risky than Broadband treament because most of the UVB is within the theraputic wavelength of 311nm, Broadband light is over a much wider wavelength – less UVB in total (and much less within the theraputic wavelength) and a greater percentage of UVA.

More generally, you must remember that all UV radiation can cause skin damage and treatments therefore have to be rationed. Doctors will not put patients at unnecessary risk. Care should be taken with the number of treatments over one year and indeed over a lifetime. This will vary from person to person depending on skin type and total dose administered.

What does the treatment involve?

The units are fitted with the latest Philips TL01 Medical Narrowband high UVB tubes exactly the same as those used in many hospitals. The whole body or just the infected areas can be exposed to the UVB.  Usually the whole body is exposed to the UVB for a short time (seconds to minutes) and precautions must be taken to protect the eyes (use Goggles provided) and genital areas should be covered.

The amount of UV is carefully monitored. A number of protocols exist depending on the individual’s skin type, age, skin condition and other factors. The skin may remain pale or turn slightly pink after each treatment. Stop treatment immediatley if you experience any discomfort. Patches of psoriasis generally start to become thinner after five to ten treatments. Most patients with psoriasis need about 15-30 treatments to clear.*

To UVB or not to UVB?

There are large numbers of studies showing the positive effect of UVB on patients. Generally 80% of psoriasis patients will be cleared within 6 weeks*, with 3 treatments per week. Patients who experience a reoccurrence within a short time after healing may use maintenance programs of treatment, once or twice per week. This also applies to other ailments such as vitamin D deficiency but these sufferers may find it more beneficial to use the lamps more in the winter months when natural sunlight (and hence Vitamin D levels) is at a minimum.

An independent study by the BMA states “that treatment of skin conditions outwith hospital is no less beneficial than the treatment in hospital” as long as the user controls their session times and frequency in accordance with the guidelines set out. Treatment independantly is much more convenient and generally more stress free than actually spending time (possibly hours) getting to a hospital, taking time off work every few days – for just a few minutes treatment.

Wrinkling of the skin (Actinic Elastosis) and skin malignancies are associated long-term side effects. However, in one study in a Swedish clinic of patients who had been on UVB treatment during a 20 year period, no increase of wrinkling of the skin or skin malignancies were found, when compared to an age and sex matched group from the same city. Narrowband minimises the risk further because most of the light emitted is now at the theraputic wavelength of 311nm.

Short-term side effects can be totally avoided by following the instructions with care. These are blistering with redness (erythema), which is uncomfortable but absolutely not dangerous. Every person has a different skin type and some burning may be experienced if session times are slightly too long for a particular skin type (particularly fair skin), this can be completely avoided by being sensible and reducing session times.

To summarise, the risks involved with UVB are about the same as for an outdoor worker such as farmer or builder, who are exposed to sunlight on a daily basis. It is advised that anyone undertaking UVB Therapy visits a dermatologist once or twice a year for regular check up.