TO ZIGMA SERIES
Photodermatitis is an abnormal
skin response to ultraviolet (UV) rays, particularly sunlight. It can be acute
or chronic. UV rays are classified by wavelength and the greater the wavelength,
the greater the risk of developing photodermatitis. UVB rays range from 290 to
320 nm and may cause sunburn, tanning, aging, or cancer-causing changes to the
skin. UVA rays range from 320 to 400 nm and may cause reactions to light even
through window glass. Ninety percent of the UV radiation from sunlight comes
from UVA rays, 10% from UVB. Photoreactions from UV rays depend upon the amount
of light reaching the earth. This is influenced by the season or time of year,
latitude, thickness of the ozone layer, and topography.
Signs and Symptoms
- Itchy bumps, blisters, or raised areas
- Lesions that resemble eczema
- Hyperpigmentation (darkened discoloration compared to
one's normal skin tone)
- Outbreaks in areas of skin exposed to light
- Pain, redness, and swelling
- Chills, headache, fever, and nausea
- Less severe symptoms after repeated exposure
What Causes It?
Certain chemical agents and
drugs may predispose an individual to sunburn, an eczema-like reaction, or hives
in reaction to UV rays. In the United States alone, there are more than 115
chemical agents and drugs that are ingested or applied to the skin that may
elicit photodermatitis. The reaction may be related to an allergy or it may be a
direct toxic effect from the substance. Below are examples of agents or
circumstances that may trigger one or the other type of reaction:
Direct toxic effect:
- Tetracycline and sulfonamides, medications used for
- Griseofulvin, used for fungal infections
- Coal tar derivatives and psoralens, such as
methoxsalen and trioxsalen, used for psoriasis
- Tretinoin and other medications containing retinoic
acid used for acne
- Nonsteroidal anti-inflammatory drugs (NSAIDs), such as
- Chemotherapy agents used to treat cancer, such as
5-fluorouracil and vinblastine
- Sulfonylureas, such as glyburide and glipizide, oral
medications used for diabetes
- Quinine and other medications used to treat malaria
- Thiazide diuretics, such as hydrochlorothiazide
- Desipramine and other medications used for depression
(known as tricylics)
- Phenothiazines, a class of medications used for
- Benzodiazepines, such as alprazolam and tetrazepam,
medications used for anxiety disorders
- Fragrances containing, for example, musk ambrette and
- Sunscreens with p-aminobenzoic acid (PABA) esters
- Industrial cleaners that contain salicylanilide
Photodermatitis may also result
from some immune-related disorders such as systemic lupus erythematosus (SLE) or
certain states of nutrient deficiencies, including pellagra, which is caused by
niacin (vitamin B3) deficiency.
Who's Most At Risk?
- Skin type may influence the likelihood of a
photodermatitis reaction. Those with fair to light skin, or those with red
or blond hair, and green or blue eyes tend to be most sensitive, regardless
of their racial or ethnic background. This is categorized as skin type I.
- Exposure to UV rays for 30 minutes to several hours
increases risk of photodermatitis (outbreaks in spring and summer months are
- Exposure to UV rays from 11 a.m. to 2 p.m. also
increases risk of photodermatitis since 50% of UV radiation is emitted
during this time.
What to Expect at Your Provider's Office
A physical exam and a detailed
history of exposure to sensitizers (see section entitled What Causes It?) and UV
rays are important for diagnosis. A review of all body systems, including blood
and urine tests, helps detect any related disease. Allergy tests may help
identify substances that trigger or worsen the condition.
These measures may help prevent
- Limit skin exposure to sun, especially intense midday
- Use sunscreens that protect against UVA and have a sun
protection factor (SPF) of 30 to 50.
- Cover up with a long-sleeved shirt, long pants, and a
- Beware of using any product that causes sun
sensitivity. (If you are already taking a prescription medication, however,
do not stop taking it without consulting your healthcare provider.)
For blisters or weepy eruptions,
apply cool, wet dressings. With certain types of photodermatitis, doctors may
actually use phototherapy (controlled exposure to light for treatment purposes)
to desensitize the skin or to help control symptoms.
For extremely sensitive
patients, doctors may prescribe azathioprine to suppress the immune system.
Short-term use of glucocorticoids may help control eruptions. For those who
cannot be treated with phototherapy, doctors may prescribe hydroxychloroquine,
thalidomide, beta-carotene, or nicotinamide (see section entitled Nutrition for
details regarding the latter two). Note: Thalidomide causes severe birth defects
and therefore should never be used by women who either are or wish to become
Complementary and Alternative Therapies
deficiencies can contribute to photosensitivity. Pellagra, for example, is
caused by a niacin deficiency. Recent research results suggest that antioxidant
nutrients, including beta-carotene, may help lessen the severity of
and Other Carotenoids: Despite the fact that beta-carotene is considered
part of standard treatment for photodermatitis, the results of studies
regarding this supplement have been mixed. One study of the effect of
beta-carotene supplements on sunburns in humans showed no significant
protection. In another trial, though, 20 healthy subjects received either
carotenoids alone, mainly from beta-carotene, or carotenoids plus vitamin E.
Both groups improved significantly. Vitamin E did not appear to add to the
benefits of the carotenoids alone.
Oil/Omega-3 Fatty Acids: In one study, 13 patients with a particular
type of photodermatitis received supplements of fish oil, which contains
omega-3 fatty acids, for three months. Tests afterward showed that the
patients were significantly less sensitive to UV rays. Similarly, case
reports of three children with hydroa vacciniforme, a rare scarring
photosensitivity disorder, found that omega-3 supplements lessened symptoms
for two of the three children. Photosensitive patients could consider eating
a diet rich in omega-3 fatty acids, such as from cold water fish.
Actinic prurigo, a form of photosensitivity marked by ongoing outbreaks of
itchy bumps during hot weather, is seen mainly in malnourished individuals.
Research suggests that the condition is related to a diet deficient in
protein or a specific amino acid (the building blocks of protein). Patients
treated with a high-protein diet have improved but tend to relapse a few
weeks after returning to their standard diet.
- Vitamin B3:
Nicotinamide (a form of niacin, or vitamin B3) may make a photosensitive
reaction less likely. In a pilot study, 42 people with photodermatitis were
given nicotinamide; despite extensive sun exposure, 25 of these people did
not develop lesions.
- Vitamins C and
E: Antioxidants, including vitamins C and E, help remove free radicals,
harmful by-products that result from cells' use and generation of energy.
Free radicals are linked to skin damage. Oral supplements of vitamins C and
E seem to work together to possibly reduce UV-induced skin reactions.
- Vitamin D:
In animal studies, vitamin D helped trigger the effects of an antioxidant
protein found in skin cells of rats. This protein helps to protect against
damage from UVB rays. It is not clear yet whether vitamin D supplements may
help protect humans in the same way.
- Green Tea:
The antioxidant properties in green tea (Camellia sinensis) may provide
protection against reddening of the skin caused by UV light.
Epigallocatechin-3-gallate (EGCG), an active component of green tea has
demonstrated photoprotection in animal studies. In a human study, tests on
skin samples showed that EGCG does not block the absorption of UVB light but
it does appear to inhibit redness, some cell damage, and other changes
normally associated with UVB rays.
- Calendula: Although
not studied scientifically, this herb has been used clinically for skin
conditions including sunburn. It may also be used as a homeopathic remedy at
doses consistent with that kind of therapy.
Similar to photosensitizing
medications, certain herbs can trigger photodermatitis; such herbs include St.
John's wort (Hypericum perforatum), angelica seed or root (Angelica archangelica),
celery stems (Apium graveolens), rue (Rutae folium), and lime oil/peel ( Citrus
While scientific studies of
homeopathy specifically addressing photodermatitis have not been conducted to
date, individual reports suggest that homeopathic remedies may be a useful
adjunct for the prevention and treatment of photodermatitis. An experienced
homeopath considers each individual case and may recommend treatments tailored
to address both the underlying condition and any current symptoms.
Most photosensitivity reactions
go away on their own and cause no permanent harm. However, symptoms can be
severe when associated with a systemic disorder or when the exposure has been
severe. Some photosensitivity reactions can continue for years after exposure
Complications may include:
- Ongoing photosensitivity, resulting in chronic
- Hyperpigmentation or dark discoloration compared to
normal skin tone even after inflammation has resolved
- Premature aging of the skin
- Squamous cell or basal cell skin cancer or melanoma
Patients who need steroids to
treat photosensitivity reactions must be monitored closely. In addition, anyone
with a history of photodermatitis or photoreactivity should keep track of the
frequency and duration of symptoms. This information can help determine the
cause and appropriate treatment.