Your dermatologist will explain how to prepare for your procedure. They will also have a chat with you about what happens before, during and after your procedure, and discuss any pain you might experience. This is a good opportunity to make sure you understand what will happen. It may help to have a think about what questions you’d like answered. These might include information about the risks, benefits and any alternatives to the procedure. Once you’re happy, you may be asked to give your consent for the procedure to go ahead by signing a consent form.
Before and during a course of light therapy, you will need to limit any additional exposure to natural ultraviolet light in sunlight. This is because you increase the risk of burning and skin damage. If you start the treatment with a suntan, higher doses of ultraviolet light will be required to achieve the same effect. You also need to make sure you don't put anything on your skin that can enhance the effects of the light.
Your doctor may give you the following advice.
- Cover your skin when out in sunlight and don’t use sunbeds.
- Don’t eat a lot of foods that contain natural psoralen, which will make you more sensitive to ultraviolet light. These include celery, carrots, figs, citrus fruits, parsnips and parsley.
- Don’t use perfumed products, creams, ointments and lotions, unless told to by hospital staff.not use perfumed products, creams, ointments and lotions unless told to by hospital staff.
- Don’t cut your hair during your treatment as it may expose skin that was previously covered by hair.
Before a treatment session, it's also important to let the hospital staff know about any new medicines you’ve started taking (including any herbal medicines). This is because some medicines can make your skin more sensitive to light.
Your dermatologist may only suggest light therapy if other treatments for your condition, such as emollients (moisturisers) and medicated creams, haven't worked. Some skin conditions are best treated by light therapy.
If light therapy doesn't work, or you’re unable to have it for any reason, your dermatologist may prescribe you a medicine instead.
If you’re having psoralen ultraviolet A (PUVA) treatment, you will usually be asked to take a psoralen tablet an hour or two before your ultraviolet A (UVA) therapy. Alternatively, you may be able to use a form of psoralen that you can add to bath water, but you will have the bath in hospital. You can also have psoralen as a cream or gel if you’re getting treatment for small areas of your skin. If you’ve had a psoralen tablet, you’ll be asked to wear ultraviolet protective glasses for 24 hours to prevent damage to your eyes. This is because psoralen makes your eyes, as well as your skin, more sensitive to natural sunlight.
Usually a trained phototherapy nurse at a hospital will administer your light therapy. Your dermatologist will work out the best dose for you to start on. This is based on your skin type and how easily you usually burn in sunlight. A test dose of ultraviolet light may be applied to a small area of your skin to help calculate the correct starting dose of ultraviolet light.
Your nurse will ask you to remove any clothing from the area to be treated. If your whole body is being treated, you will keep your underpants on or use a genital shield. You will also be given goggles to protect your eyes during treatment. Your nurse may ask you to apply sunscreen to protect certain parts of healthy skin, for example your neck, lips and nipples.
The ultraviolet light is produced by fluorescent tubes in specially designed cabinets. If you’re having treatment for your palms and or soles only, a smaller unit can be used to just treat these areas.
In the first few sessions, your treatment may last for less than a minute. The duration will be gradually increased in later sessions, depending on how you respond to light therapy.
You will usually be able to go home immediately after your treatment. Your nurse or dermatologist will give you some advice on how to manage any side-effects.
If you have had psoralen ultraviolet A (PUVA), you will be asked to carry on wearing ultraviolet protective glasses for 12 to 24 hours. You will also need to make sure your skin is covered if you’re outside or inside near a window.
As with every procedure, there are some risks associated with light therapy. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your dermatologist to explain how these risks apply to you.
Side-effects are the unwanted but mostly temporary effects you may get after having the procedure.
The following are possible side-effects of light therapy.
- Red skin, similar to sunburn. This should fade over the days following your treatment. You can use moisturisers to help relieve any discomfort.
- Dry and itchy skin. Moisturisers may help to relieve this.
- A rash.
- Cold sores (if you get them).
- Feeling sick if you’ve had psoralen ultraviolet A (PUVA) treatment. Your dermatologist may suggest that you try a different type of medicine or use a PUVA bath if you feel sick with psoralen tablets.
Complications are when problems occur during or after your treatment.
As with natural sunlight, repeated sessions of ultraviolet B (UVB) and PUVA light therapy can increase your risk of skin cancer and premature skin ageing over the long term. The risk is higher the more sessions of light therapy you have. Because of this, your dermatologist will always make sure that you receive the least UVB or PUVA treatment possible to provide a beneficial effect. They will also keep a record of the amount of light therapy you have had in total, to make sure your dose is within safe exposure limits.
There's also a risk of damage to your eyes with PUVA. However, wearing eye protection will reduce this risk.
Why can't I just use natural sunlight and sunbeds to treat my psoriasis?
Natural sunlight is known to be helpful for many people with psoriasis. However, it can be hard to control how much you get and keep it within a safe amount. Sunbeds are of limited or even no value in treating psoriasis, as they don’t usually produce the most effective wavelength of light.
Ultraviolet light therapy in a hospital is carefully controlled in terms of both the dose that is delivered to your skin and the wavelength of the light used. Both of these factors will be recorded as your treatment is gradually increased. This means you can be given the most effective light treatment in the safest way.
While natural sunlight can be helpful for people with psoriasis, you need to be careful to avoid overexposure to the sun and sunburn. Talk to your doctor about how to get the most from the sun while keeping safe. If you’re already receiving light therapy in hospital, you will be advised to avoid sunlight during a treatment course.
Unfortunately, high street sunbeds aren’t tightly controlled, so the exact spectrum of light emitted or dose of light delivered may not be optimal to balance treating the condition against your risk of skin cancer. In addition, the amount of ultraviolet B (UVB) light, which is the most effective type of light for treating psoriasis, is frequently reduced in high street units, as it can be associated with burning if not used carefully. This means that the light produced by sunbeds may be of no benefit in treating psoriasis or it may even be harmful. There is very good evidence demonstrating the link between sunbed use and the risk of skin cancer.
Is light therapy for seasonal affective disorder (SAD) the same as that for skin conditions?
No. With SAD, you can buy your own light-emitting device, such as a light box or dawn simulator, to use at home or at work. You don't have to go to hospital for this type of light therapy as it’s a different type of light to that used in the treatment of skin conditions.
The devices that are used for this type of light therapy contain bright light tubes that emit visible (non-ultraviolet) light at least 10 times the intensity of ordinary household light bulbs. To use them, you need to make sure the light is directed towards your eyes. The wavelength of the light is not the same as in ultraviolet B (UVB) or psoralen ultraviolet A (PUVA) therapy.
UVB or PUVA therapy for skin conditions uses only the ultraviolet part of light, as this is the part that is beneficial. You will usually have it in a hospital under the supervision of medical staff. It’s directed at your skin, while your eyes are protected.
Should I carry on using creams and other treatments for psoriasis while I have light therapy?
It can be effective to take other treatments at the same time as having light therapy, but talk to your dermatologist about what is best for you.
Your dermatologist may recommend light therapy in combination with other treatments such as steroid cream. This may help to improve your psoriasis if your symptoms aren’t clearing with topical treatment alone.
It can also help to carry on using emollients during your treatment, as this can affect how much ultraviolet light penetrates your skin. However, ask your dermatologist for advice about any creams you’re using as some may protect your skin from the light and reduce the effect of the treatment.
If you’re taking tablets for psoriasis, it’s important to let your dermatologist or phototherapy nurse know, as some tablets can increase your skin’s sensitivity to sunlight.
- Seasonal affective disorder. PatientPlus. www.patient.co.uk/patientplus.asp, published 12 September 2013
- Phototherapy for jaundice. Medscape. www.emedicine.medscape.com, published 19 September 2013
- Psoriasis. NICE Clinical Knowledge Summaries. cks.nice.org.uk, published December 2012
- Psoriasis. Medscape. www.emedicine.medscape.com, published 3 April 2014
- Menter A, Korman NJ, Elmets CA, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: Section 5 – Guidelines of care for the treatment of psoriasis with phototherapy and photochemotherapy. J Am Acad Dermatol 2010; 62(1):114–35. doi: 10.1016/j.jaad.2009.08.026
- PUVA. PatientPlus. www.patient.co.uk/patientplus.asp, published 20 June 2014
- Chronic plaque psoriasis. PatientPlus. www.patient.co.uk/patientplus.asp, published 20 November 2012
- Psoriasis: the assessment and management of psoriasis. National Institute for Health and Care Excellence (NICE). October 2012. www.nice.org.uk
- Phototherapy. National Psoriasis Foundation. www.psoriasis.org, accessed 22 July 2014
- Psoriasis (chronic plaque). BMJ Clinical Evidence. www.clinicalevidence.bmj.com, published 9 January 2009
- Glickman G, Byrne B, Pineda C, et al. Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs). Biol Psychiatry 2006; 59(6):502–7
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