Note: This review will focus primarily on nontargeted light therapies. Photochemotherapy, photodynamic therapy (PDT), photopheresis, ocular light therapy, and targeted light therapy, such as laser and intense pulsed light (IPL), will not be extensively discussed. The graded conditions reflect the level of scientific evidence to support the efficacy of nontargeted light therapy, used as a monotherapy.
Light therapy, also known as phototherapy, involves exposing skin to different wavelengths of light. Light therapy may be performed using lasers, light-emitting diodes (LEDs), fluorescent lamps, dichroic lamps, or very bright full-spectrum light. Treatments are performed regularly for a certain amount of time, under the supervision of healthcare professionals. Light therapy treatments may be given to the whole body or to smaller areas.
Light therapy is a first-line treatment for jaundice in newborns (yellowing of skin in babies), severe plaque psoriasis (flaky, itchy skin disease), and seasonal affective disorder (SAD). It is also used for many skin conditions including atopic dermatitis (itchy skin disorder), acne, morphea (hardened skin patches), vitiligo (loss of color in skin), urticaria (hives), and pruritus (itchy skin). Treatment with light has been extended to other conditions, including nonseasonal mood disorders, memory loss, circadian-related sleep disorders, and eating disorders.
Side effects of phototherapy are generally mild and short-term and include nausea, headache, and skin irritation. Like natural sunlight, long-term exposure to ultraviolet light may cause skin damage, skin cancer, or eye damage. Caution is needed in people who have a history of skin cancer or eye disease or are using agents that may increase their sensitivity to light.
In general, studies on the use of light therapy have been small and poorly reported. More high-quality research is needed.
Light therapy has been used for a variety of medical conditions, ranging from skin disorders to psychiatric illnesses.
The use of light therapy in medicine has a long history. Although research was lacking, natural sunlight was used for medical treatments in ancient Egypt and Greece. Later, Roman and Arab physicians introduced light therapy into general medical use.
Today it is known that the human body transforms light into energy, which activates a chain of reactions within cells, stimulating metabolism and strengthening the immune response of the entire body. The human response to light therapy is more complicated. Natural sunlight does not offer wavelengths of useful light in strong enough concentrations.
Effectiveness of phototherapy may depend on light energy and distance between the lamps and the person being treated. Different units and devices have different recommended treatment distances, with most suggesting a distance of 10 inches from the bulbs to the skin.
Many phototherapy devices have been developed using different light sources such as blue and special blue fluorescent tubes, halogen, fiberoptic, and light-emitting diode (LED) sources. Light may be delivered directly or through filters. Devices may deliver phototherapy to the entire body or to a specific area (spot treatment). Treatments may take place in a doctor's office, phototherapy center, or hospital. Home phototherapy systems are also available.
Acu-light therapy: This therapy involves the use of color light sequences applied to sets of points on the body to connect light between mind, body, and soul.
Balneophototherapy and bath PUVA phototherapy: This involves the use of long-wave ultraviolet (UV) radiation plus a psoralen (agent that increases light sensitivity) delivered in a diluted bath solution. Bath psoralen-ultraviolet A (PUVA) phototherapy is reportedly an effective alternative option to PUVA taken by mouth for skin conditions like psoriasis, with fewer side effects. Some types of bath PUVA use highly concentrated salt solutions to treat atopic dermatitis and psoriasis.
Fiberoptic phototherapy (Biliblanket®, Wallaby®): The bilirubin blanket is used to treat newborns with jaundice and delivers light through a fiberoptic cable to a pad. The pad is placed on the baby's back.
Intense pulsed light (IPL) therapy: This therapy produces high intensity light over a short length of time. It uses polychromatic light, a spectrum of different wavelengths as opposed to one wavelength like laser.
Ocular light therapy (OLT): Ocular light therapy delivers light and color through the eyes directly to the brain. This form of light therapy is being used for psychological disorders.
Photodynamic therapy (PDT): This therapy involves the use of agents that increase light sensitivity along with a light source and oxygen, and is used to treat cancers of the head and neck, brain, lung, pancreas, stomach cavity, breast, prostate, eyes, and skin.
Psoralen-ultraviolet A (PUVA) phototherapy: Psoralen plus ultraviolet A (PUVA) phototherapy combines UVA light with an agent called a psoralen. This agent increases light sensitivity and is taken by mouth or applied directly to the skin or in a bath solution (bath PUVA). This treatment is usually used in people who do not respond to ultraviolet B therapy, and is used for different types of psoriasis.
Ultraviolet A (UVA) therapy: This therapy exposes skin to UVA light of wavelengths around 320-400 nanometers. Broadband UVA irradiation (315-400 nanometers) contains both UVA1 (340-400 nanometers) and UVA2 (315-340 nanometers). Long-wavelength ultraviolet A light (UVA1, 340-400 nanometers) was developed as a "pure", high intensity UVA source. Unlike UVB which only penetrates the surface layer of skin, UVA1 penetrates deeper layers and is typically used for atopic dermatitis and psoriasis.
Ultraviolet B (UVB) therapy: This therapy exposes skin to UVB light of wavelengths around 280-320 nanometers. Narrowband UVB phototherapy of wavelength 311 nanometers uses a smaller spectrum of light.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Light therapy has been used in combination with other treatments to reduce acne and acne scars. Blue light therapy and red light together may improve acne and fight the bacteria responsible for causing the condition. Non-targeted blue and red light treatments have also been found to be useful for people with acne vulgaris. More studies are needed comparing the effects of light therapy to those of other acne treatments.
Phototherapy may be used in combination with other treatments for adults who have atopic dermatitis, an itchy skin rash. Both UVB and UVA light have been used for this condition. Light therapy is believed to benefit children as well, but there is debate surrounding the potential increased risk of skin cancer with long-term use. Long-wavelength UVA1 in medium doses may benefit people who have acute eczema, while narrowband UVB treatment may be more effective for chronic disorders.
Light therapy may be considered as an alternative treatment for the herpes virus when drug therapy is not possible. Short-term phototherapy has been shown to be effective in reducing cold sore healing time. Additional research is warranted.
Phototherapy is currently used to treat cutaneous T-cell lymphoma. Narrowband UVB phototherapy has been found to be effective in the early stages of the disease. Some researchers believe that it may have advantages over broadband UVB and photochemotherapy (PUVA), such as fewer long-term side effects. UVB phototherapy and PUVA are considered first-line treatment options for people who have early stage lymphoma. The use of phototherapy alone is not recommended for people with late-stages of mycosis fungoides, a common form of cutaneous T-cell lymphoma.
Jaundice is a common problem for newborns during the first week of life. Failure to treat may result in severe side effects such as brain damage. Phototherapy is the first line treatment for babies with jaundice in both developed and developing countries of the world. The effectiveness of light therapy depends on body surface area, wavelength of light, distance from light, and length of exposure.
Light therapy using UVB or PUVA is considered one of the main treatment options for psoriasis. Lasers and a combination of salt bath and phototherapy may also benefit people with this condition. Light therapy has been combined with retinoids (compounds related to vitamin A) for the treatment of psoriasis. This may be more beneficial than phototherapy alone and is thought to reduce the risk of skin cancer that may increase with long-term light therapy use.
Light therapy may benefit people with scleroderma. Broadband UVA and UVA1 may be effective for damage deeper beneath the skin, while narrowband UVB therapy may be effective for damage closer to the surface. There is strong evidence in support of the use of broadband UVA, narrowband UVB, and UVA1.
Light therapy is recommended as a first treatment option for people with SAD. It has been used in combination with other treatments for long-term, major depressive disorder, and less severe depression that relates to seasonal changes. Fluorescent light box is recommended, but optimal timing and length of light exposure vary between studies.
Light therapy may be used alone or in combination with other agents or treatments for vitiligo. Narrowband UVB is considered a first-line option for this disease. Combination therapy may be more effective than UVA, broadband UVB, and narrowband UVB alone.
Light therapy may be effective in promoting wound healing and tissue repair. However, the optimal treatment method is unclear and more study is needed before conclusions can be made.
People with disorders such as Alzheimer's disease may experience sleep problems. Light therapy may be a good treatment option for sleep difficulties and may also improve behavioral and psychiatric disturbances. Some results are still unclear and more research is needed to clarify these findings.
There is conflicting evidence for the use of light therapy in treating nonseasonal depression. Research suggests that light therapy may benefit women who have depression during the menstrual cycle or during pregnancy. However, results are inconclusive.
Limited evidence shows that light therapy may help people with bulimia. Preliminary results suggest that bright light therapy may also help people with anorexia or night eating syndrome. However, more research is needed to confirm these results.
Light therapy may increase the rate of healing and reduce the time to heal in people with pressure ulcers. However, more research is needed before conclusions can be made.
UVB light appears to be promising for the treatment of pruritus caused by kidney disease. However, more research is needed before a conclusion can be made.
Light therapy may be useful for treating sleep disorders, including difficulty falling asleep and jet lag. Effectiveness depends on the dose and length of light exposure, as well as time of day the exposure takes place. However, there is limited data and conclusions are lacking. More studies are needed to look at the effectiveness of light therapy in older people compared to other populations.
Phototherapy with or without the use of a psoralen, a natural plant product that increases light sensitivity, may benefit people with hives. Although results are promising, more studies are needed to determine the proper dose and long-term effects.
Preliminary research suggests that a combination treatment that includes light therapy may benefit people with brain tumors. Large, well-designed clinical trials are needed before further conclusions can be made.
Light therapy in combination with other treatments may benefit people who experience complications from eye diseases like macular degeneration (loss of vision due to retina damage). Light therapy may help reduce risk of vision loss, but the effectiveness of light therapy alone is not clear at this time.
Phototherapy has been studied for the treatment of lichen planus in the mouth. Narrowband UVB phototherapy and PUVA may benefit people with this disorder. However, preliminary research shows that PUVA may have many side effects. More studies looking at the use of light therapy alone are needed before conclusions can be made.
Combination treatments that include light therapy may be used to treat skin warts. However, there is a lack of evidence to support this treatment and a lack of evidence for the use of phototherapy alone. More studies are needed before a conclusion can be made.
* Key to grades
A: Strong scientific evidence for this use B: Good scientific evidence for this use C: Unclear scientific evidence for this use D: Fair scientific evidence for this use (it may not work) F: Strong scientific evidence against this use (it likley does not work)
Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Autoimmune disorders (immune system attacks own body), cancer, fibromyalgia (joint pain and tenderness), graft healing (skin transplant surgery), immune disorders, inflammatory conditions, multiple sclerosis (nervous system disease), nerve damage, pain, Parkinson's disease (brain disorder and muscle shaking), tuberculosis (bacterial lung infection).
Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.
Note: It is recommended that people use light therapy under the supervision of a qualified professional, rather than attempting to self-medicate. Experts suggest that people wear eye protection when undergoing light therapy. People may need to wear special clothing to protect sensitive areas, such as the genitals, from being burned during light therapy.
Light therapy is likely safe when used to treat conditions for which studies or long history of use have shown is safe and effective, such as psoriasis, seasonal effective disorder (SAD), and neonatal jaundice, under a doctor's care.
Light therapy is possibly safe when used in combination with a psoralen agent taken by mouth or applied to the skin prior to undergoing psoralen-ultraviolet A (PUVA) for fewer than 250 treatments or for less than three years under a doctor's care.
Non-targeted light therapy used alone is possibly safe during pregnancy and breastfeeding.
Drowsiness or sedation may occur. Use caution if driving or operating heavy machinery.
Sun allergy or sun poisoning is an immune system reaction triggered by the sunlight. There are different types of sun allergy and symptoms may vary, but typically produce an itchy red rash. Blisters, hives, skin eruptions, chills, headache, nausea, and a feeling of being unwell may also occur.
Use cautiously in people who are taking agents that may affect the immune system, agents that may increase light sensitivity, depressants, vitamin A, vitamin C, and vitamin D or vitamin D analogues.
Use cautiously in people with autoimmune disorders, changes in bowel habits, dementia, eating disorders or changes in appetite, headaches or migraines, human immunodeficiency virus (HIV), light sensitivity disorders, muscle pain and weakness, nausea, Parkinson's disease or other movement disorders, psychiatric disorders, risk of dehydration, risk of eye problems, sexual dysfunction, skin cancer, stomach disorders, stomach pain, and weak immune systems.
Use cautiously in combination with cyclosporine. Combined use may increase the risk of cancer (squamous cell carcinoma), high blood pressure, kidney problems, and liver toxicity.
Use cautiously in combination with hydroxychloroquinine. Combined use may cause skin reactions.
Use cautiously in combination with methotrexate. Combined use may increase the risk of cancer of the immune system (lymphoma) and cirrhosis (liver scarring).
Use cautiously in combination with retinoids applied to the skin, such as tazarotene. Combined use may thin the skin and increase the risk of burn when given with ultraviolet (UV) light.
Use cautiously in combination with melatonin. Combined use may worsen behavior in people with dementia.
Use home phototherapy systems cautiously for the treatment of psoriasis. Medical supervision is recommended.
Use cautiously in elderly people, as they may be using one or more sun-sensitive agents and may have a higher risk for light sensitivity reactions.
Avoid using PUVA during pregnancy. Avoid taking retinoids by mouth in combination with phototherapy for the treatment of psoriasis in pregnant women.
Light therapy may also cause side effects such as aggression, aging of skin, agitation, anxiety, birthmarks (in babies), blisters, burning sensation, changes in appetite, changes in body temperature, changes in sleep duration and quality, constipation, darkening of skin, decreased sex drive, delusions, diarrhea, disruption of mother-baby relationship, dry skin, elevated mood, eye damage, dryness, or strain, first-degree burns, flushing, headaches, heat sensation, herpes simplex recurrence, increased skin cancer risk, interruption of breastfeeding in babies, irritability, itchiness, jitteriness, loss of skin, male erection problems, muscle pain, tremors, or weakness, nausea, nervousness, skin inflammation or irritation, skin rash or redness, sleep difficulty, stomach problems, sweating, thinning of skin, vision disturbances, impaired transfer of water from body to skin, weight loss (in babies), worsened dementia symptoms, or worsened depression symptoms.
Light therapy may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, and alcohol. Caution is advised while driving or operating machinery.
Light therapy may also interact with agents that affect the immune system, agents that cause movement problems (extrapyramidal), agents that increase light sensitivity, antibiotics, antidepressants, antiretrovirals, antivirals, depressants, cyclosplorine, hydroxychloroquine, immunoglobulins, metalloporphyrins, methotrexate, phenobarbital, retinoids, and vitamin D analogs.
Light therapy may increase the amount of drowsiness caused by some herbs or supplements.
Light therapy may also interact with herbs and supplements, including antibacterials, antidepressants, antiretrovirals, antivirals, herbs and supplements that affect the immune system, herbs and supplements that cause muscle tremors, herbs and supplements that increase light sensitivity, khellin, melatonin, Polypodium leucotomos, Picrorhiza kurroa, vitamin A, vitamin B12, vitamin C, vitamin D, and vitamin E.
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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.