What is a photosensitivity reaction?
Some medications and foods contain photosensitizing substances, which are actually a class of compounds such as furanocoumarins, the most common. When the body is exposed to sunlight after using a drug or food containing a photosensitizing substance, the skin’s difficulty in absorbing the sun’s ultraviolet rays is reduced or increased, mediated by the photosensitizing substance, resulting in a specific biological reaction, usually on the skin and, to a lesser extent, in the eyes and mucous membranes. This is also known as a photosensitivity reaction.
How are photosensitivity reactions differentiated?
Photosensitivity reactions are divided into “phototoxic dermatitis” and “photomimetic dermatitis”. “Phototoxic dermatitis” is a condition in which a photosensitive substance enters the body and is distributed to the skin after taking photosensitizing drugs, food, or injections, and then absorbs ultraviolet light in the sun for a few hours (usually 2 to 3 hours) to cause skin disease.
In clinical terminology, it is a non-immune reaction with rapid onset, short onset time and quick elimination. In contrast, “photomimetic dermatitis” is caused by exposure to the sun after taking photosensitizing medications or foods, but does not develop immediately and usually develops within 2 to 4 days. The onset of this type is characterized by slow onset, recurrence, and slow fading, and is an immune response.
The general symptoms of photosensitivity dermatitis are itching, burning sensation, redness and even blistering of the skin.
What drugs or foods are photosensitizing?
Drugs and foods that cause photosensitivity.
Sulfonamides: such as cotrimoxazole; Antibiotics: such as tetracycline, etc;
Antifungal drugs: such as ashwagandha and voriconazole, etc;
Quinolones (fascias): such as levofloxacin, ciprofloxacin, ofloxacin, norfloxacin, pyrimethamine, etc;
Antihistamines: such as paracetamol, desipramine, benadryl, etc;
Tranquilizers: such as Librium;
Antipyretic drugs: such as aspirin, painkillers, ibuprofen, ketoprofen, etc;
Diuretics: such as dihydrocoumaric acid, tachyphylaxis, etc;
Cardiovascular: Amiodarone, quinidine, nifedipine, etc;
Anti-malarials: such as chloroquine, etc;
Antitumor drugs: such as vincristine, etc;
Glucose-lowering drugs: such as glibenclamide, glipizide, etc;
Phenothiazine antipsychotics: such as chlorpromazine, etc.
Chinese herbs and proprietary Chinese medicines: forsythia, bamboo yellow, sensitizer bone marrow, dahurica, white fresh bark, Xianhecao, etc.;
Food: celery, rape, spinach, fennel, amaranth, purple clover, mustard, figs, etc..