What are photosensitive substances and how to prevent them? Photosensitive substances refer to substances that can easily cause solar dermatosis. Generally speaking, light-sensitive substances enter the skin after being absorbed by the human body, and after being irradiated by strong light, they cause phototoxic reactions and phototoxic reactions, resulting in skin rashes at exposed parts of the body, accompanied by obvious itching, burning or tingling. Photosensitive food: Bullacta exarata, bamboo lice, grey cabbage, Chinese milk vetch, Chinese cabbage, snow cabbage, lettuce, amaranth, shepherd's purse, Malantou, beet, Salsola salsola, Herba Portulacae, celery, radish leaves, spinach, buckwheat, coriander, safflower, auricularia, Sophora japonica, fig, bamboo parasitic fungi. Among vegetables, the most typical photosensitive food is gray vegetables, but it is relatively rare at present. Celery, lettuce, rape, spinach, Chinese cabbage, Chinese milk vetch, mustard, Malantou, fig, etc., although they contain photosensitive substances, whether they will cause solar dermatosis depends on individual differences, so people with allergies should try to avoid eating them. Photosensitive Chinese medicines: Radix Angelicae Dahuricae, Fructus Psoraleae, Zhuhuang, Herba Schizonepetae, Radix Angelicae Pubescentis, Radix Saposhnikoviae, Radix Adenophorae, Radix Peucedani, Herba et Gemma Agrimoniae, Zhuhuang, Cortex Dictamni Radicis, Ruxiang, Ranunculus Ranunculata, Herba Agrimoniae, etc. Photosensitive western medicine: sulfonamides and their derivatives (hypoglycemic agents), aspirin, sodium salicylate, tetracycline, griseofulvin, chlorpromazine, promethazine, dihydrochlorthiazide, furosemide, diphenhydramine, chlorpheniramine, diazepam, and oral contraceptives (estrogen). Cosmetic perfume such as bergamot oil, lemon oil, sandalwood oil, impure vaseline, musk and Long Xianxiang; Sunscreen sunscreen (p-aminobenzoic acid and its ester compounds); Dyes such as ethacridine, methylene blue and eosin; Industrial asphalt; Soaps-halogenated phenols (hexachlorophenol); Fluorescent whitening agent; Precautions for the treatment of photosensitive allergic dermatosis of fragrant beans such as Psoralea corylifolia: First of all, the most effective treatment is to stay away from allergens. Second, use antihistamines. For patients with asthma, glaucoma, liver and renal insufficiency, be very cautious before taking any antihistamine drugs. For example, Sismin has a serious cardiotoxic reaction, which can cause arrhythmia, ventricular fibrillation and even death. At present, it is not recommended to use it. Vitamin B, especially nicotinamide, is often taken orally to reduce the skin's sensitivity to sunlight. Allergy is caused by immune system disorder, which may occur at a certain stage, and it is not a lifelong trap. Prevention is more important than treatment. We should pay attention to daily life, proper diet and proper physical exercise.