As the saying goes, "Everything grows by the sun." "Ultraviolet rays in sunlight not only have the effect of sterilization and disinfection, but also promote the synthesis of vitamin D, thereby promoting calcium absorption and preventing osteoporosis." Proper sun exposure is good for health. However, some drugs should be avoided from the sun during use because they may trigger photosensitivity reactions.

Redness, itching, burning pain Consider the photosensitivity reaction of the drug

Everyone knows more or less about the contraindications of taking drugs, such as some drugs can not be taken together, can not drink alcohol after eating certain drugs, and so on. As everyone knows, there are many drugs, and photosensitivity reactions will occur after taking them, so you have to pay attention to sun protection. Photosensitization reactions to drugs have been reported to account for 8% of drug-induced adverse skin events.

The main manifestations of drug-induced photosensitivity reactions are: erythema, edema, accompanied by itching, burning pain, or pigmentation, such as darkening of the skin or pigmentation. Severe cases may have blisters, and ulcers or erosions may form after ulceration.

The photosensitivity reaction of drugs is an adverse reaction of the skin to light after administration. Including phototoxic reactions and photoallergic reactions. The former refers to the release of ultraviolet light energy absorbed by the drug in the skin, resulting in skin damage; The latter is an activated state after the drug absorbs light energy, and binds to skin proteins in the form of haptens to become whole antigens, which are transmitted to immunocompetent cells through epidermal Langerhans cells, causing skin allergic reactions.

There are two conditions for a photosensitive reaction to occur: one is the use of drugs with light sensitivity; The second is to receive a certain amount of sunlight.

Taking these two types of therapeutic drugs is the most "unsightly"

From the analysis of the distribution of drugs that can cause photosensitivity reactions, drugs that are more likely to cause photosensitivity reactions are nervous system drugs and anti-infective drugs, followed by cardiovascular system drugs and endocrine system drugs. Antineoplastic drugs, anti-inflammatory drugs, and other kinds of drugs are comparable in their ability to cause photosensitivity reactions.

Here are some commonly used Western drugs that can cause photosensitivity reactions:

Diuretics hydrochlorothiazide, furosemide

Antiarrhythmic drug Amiodine

Nonsteroidal anti-inflammatory drugs naproxen, ketoprofen, piroxicam

Antimetabolites methotrexate

Antineoplastic drug dabrafenib

Antimicrobials tetracycline, doxycycline, voriconazole, quinolone antibacterial

Antipsychotic promethazine

Lipid-regulating drug fenofibrate

Antifibrotic drugs pirfenidone

It should be reminded here that there are many drugs that can cause photosensitivity reactions, but the incidence of photosensitization reactions is relatively low compared with the drugs listed above. Therefore, it is recommended that you carefully read the instructions before taking the drug to avoid adverse reactions.

Proprietary Chinese medicines and foods can also cause photosensitivity reactions

Chinese (traditional) medicines that can cause photosensitive reactions are: forsythia, bamboo yellow, Sanjiu gastric tai, psoralen, purslane, purple vetch, solitary living, sand ginseng, baizhi, white fresh skin, fairy crane grass, qianghu, windproof, wattle mustard, etc., in addition, triptolian polyglycoside has also been reported.

It is worth noting that there are some foods that can also produce photoallergic reactions, such as coriander, celery, rape, mustard greens, figs, lemons, yellow mud snails, etc. If you eat a lot of food and then bask in the sun, "vegetable solar rash" and "yellow mud snail solar rash" will occur.

To prevent the occurrence of photosensitivity reactions, we need to carefully read the drug instructions and consult a doctor or pharmacist before using the drug to understand whether the drug is photosensitive; At the same time, pay attention to sun protection during the medication period and within 5 days of stopping the drug; In addition, patients can also adjust the time of taking the drug to avoid light, such as adjusting to the evening dose.

Photosensitivity reactions can be done

Photosensitivity reactions occur, the drug should be discontinued immediately. Quickly place in a place protected from light, remove the residual allergens on the skin in time, keep away from photosensitive substances, and avoid sunlight.

In addition, the use of sunscreens can be considered, depending on the condition, severe cases are discontinued and antiallergic drugs are given; In cases where phototoxicity is particularly severe, oral antihistamines and topical or systemic corticosteroids can be used to relieve symptoms; In mild cases, antihistamines are given for treatment, and if small blisters appear, 1% gentamicin can be used to wet compress. It can also be treated with oral carotene, compound vitamin B, vitamin C, folic acid and other desensitizing drugs.

Once a drug photosensitivity reaction occurs, it is recommended that you go to a regular hospital in time while doing a good job of sun protection, and a professional doctor will make corresponding diagnosis and treatment according to your condition.

Text/Li Hongru Zhu Ying (Beijing Chaoyang Hospital)