|
||||||||||
|
|
||||||||||
Drugs can cause skin reactions
Originally published in Mayo Clinic Health Letter, July 1998
You were only in the sun a short while. You wore sunscreen. So why is your skin suddenly red, blotchy and blistered?
The cause of your problem may be something you applied to your skin or consumed. Some drugs and skin-care products can make your skin more sensitive to sunlight. Knowing what may trigger a reaction like this might keep your day in the sun from turning into days and nights of discomfort.
A chemical reaction
Certain chemicals in medications and products can make skin more sensitive to ultraviolet (UV) light from the sun or from artificial sources, such as tanning beds. They make you "photosensitive."
If you're photosensitive, you're at risk of experiencing a "photoreaction." After even brief sun exposure, your skin may become red, itchy, bumpy, swollen or blistered.
Photoreactions are not the same as a sunburn. If you have a sunburn, the sun is the only thing affecting your skin. With a photoreaction, the sun acts in combination with a chemical in or on your body to cause the reaction. Photoreactions also typically last longer than a sunburn perhaps 72 hours or more and can be more painful.
Will you react?
Anyone, at any age, can develop a photosensitive reaction to a medication or product. Fair-skinned people are no more susceptible to photosensitivity than dark-skinned people. You can develop a reaction even if you tan easily.
The degree of your reaction may vary. You may take a photosensitizing medication one time and have a mild reaction to the sun. Another time, with the same drug, you may have a severe reaction. Once sensitized to a substance, you can react to it again and again, often with increasing severity.
In addition, as long as any amount of the drug is in your system, your skin will remain photosensitive. That means you may be photosensitive for a few days after you stop taking a medicine.
Reactions also vary from person to person. What affects you may have no effect on someone else.
A variety of causes
Chemicals that produce photoreactions are called photoreactive agents or photosensitizers. Products that contain these are said to be "photosensitizing." Some common photosensitizing drugs include:
Most photosensitizing medications carry a warning.
Over-the-counter skin and hair products that may make your skin more sensitive to sunlight include:
Over-the-counter products may not carry a warning. To be safe, you may want to read labels and avoid products that contain known photosensitizers, such as quinoline, musk ambrette, 6-methyl-coumarin, bergamot oil and sandalwood oil. In addition, the herbal remedy St. John's wort may cause photosensitivity in some people.
What you can do
If you have to be on a photosensitizing medication, take extra precaution in the sun. Avoid peak sun hours, and use a sunscreen (preferably one containing a total sun block, such as zinc oxide or titanium dioxide).
A sunscreen alone, though, is not necessarily adequate. It's also important to wear protective clothing, including a broad-brimmed hat and sunglasses.
If you do have a photosensitive reaction, treat it as you would a sunburn. Take a cool bath or shower and use over-the-counter pain relievers (follow label directions). You may also want to contact your doctor. For severe reactions, prescription medications may help ease symptoms. In some cases, you may be able to switch to a nonphotosensitizing drug.
Any unexplained rash that persists for more than a few days should be evaluated.
|
ถ้าท่านชอบ
web นี้
|
mailto:vichiena@yahoo.com