All-trans retinoic acid dissolves keratin, induces epidermal proliferation, and exfoliates by regulating the abnormal process of epithelial keratinization in the sebaceous glands of hair follicles, thus preventing and eliminating acne production. It can be used to treat acne, psoriasis, ichthyosis, lichen planus, keratosis palmaris, and other keratotic diseases. Due to the eagerness to get rid of acne, many acne patients apply retinoic acid ointment to their face as soon as they wake up in the morning. Some patients even apply retinoic acid ointment topically to their face three times a day without reading the instructions. In fact, without paying attention to the application method and dosage, some adverse reactions often occur. The drug is to be applied twice a day. When treating facial acne, the concentration of retinoic acid ointment should be less than 0.05% for each application, and should not be used during the daytime as much as possible. Because retinoic acid has an irritating effect on the skin, if applied during the day, the face is prone to erythema and burning sensation, and it is also prone to hyperpigmentation after exposure to sunlight. This reaction will increase with the concentration of the drug. Therefore, it should be applied daily at night or before bedtime (or once every other day if the irritation is too strong). It should be noted that some mild irritation may occur at the beginning of the application of retinoic acid ointment, and the skin can mostly adapt and tolerate it. If irritation persists or worsens, the use of the drug can be suspended under the guidance of a doctor. Do not use other medications while using retinoic acid ointment to avoid excessive irritation. The use of retinoic acid ointment for acne will aggravate the lesions at first, but will improve after 3-4 weeks, so patients do not need to worry. When using retinoic acid ointment, you should also pay attention to the following points: 1. Do not apply to the thinner folds of the skin. 2, the concentration should not be too high, especially the face should be below 0.05%, so as not to cause local irritation. If the reaction is serious, the drug should be stopped immediately. For the treatment of other skin diseases, such as psoriasis, facial warts and keratosis, the concentration can be slightly higher. 3, Acute dermatitis, eczema-like dermatitis, eczema-like disease patients should not use retinoic acid ointment. 4.It is prohibited for women in the first 3 months of pregnancy and during lactation. 5.Used for the treatment of acne, at least 6 weeks to achieve optimal efficacy. 6.The drug can cause severe irritation or flaking. Start using the drug every other day or once every 3 days or under medical supervision. 7.Children must be used with caution under parental supervision. 8.Do not share with soap and other detergents, preparations containing anti-dandruff medicine, isotretinoin, etc., which may aggravate skin irritation or dryness.