It is generally considered that there is no problem with the exposure to light of retinoic acid ointment. Tretinoin ointment should not be exposed to daylight, because the ultraviolet rays in it will cause the decomposition of Tretinoin after seeing daylight, which appears to be significantly accelerated, so that the occurrence of local adverse reactions will be significantly amplified. For example, if a patient originally experienced slight local redness, swelling, tingling, or peeling after applying retinoic acid, these adverse reactions may be significantly aggravated when applied during the day. And in animal studies, there may also be a carcinogenic risk present if repeated sunlight exposure to retinoic acid cream ointment is performed. Therefore, patients who have applied retinoic acid ointment are generally instructed not to see daylight and to apply it at bedtime or in the evening. However, there is a clear difference between light and daylight, so there is generally no special problem with seeing light, and patients do not need to be particularly worried.