Tianqidan Emulsion turns black when used with Kiehl's freckle removing essence.

I'm sorry to hear about your trouble. According to the situation you described, Tianqidan Emulsion and Kiehl's Freckle Removing Essence turned black after being used together, which was really confusing. Generally speaking, this situation may be related to the following aspects:

It may be caused by the interaction between the components of the two products. Everyone has different skin types and sensitivities, and may have different reactions to different cosmetic ingredients. Therefore, when using different brands or different types of skin care products, it is necessary to pay special attention to whether the ingredients are compatible.

It may be caused by improper use. It is very important to use skin care products correctly, including dosage, massage technique and order. If used improperly, it may affect the effect of the product and even lead to counter-effect.

It may also be your personal skin problem. Some people are allergic to certain ingredients, or prone to skin sensitivity problems, so you need to choose carefully when using new products.

In view of the above problems, I suggest you stop using Tianqidan Emulsion and Kiehl's Freckle Fading Essence at the same time, and observe for a period of time to see if there is any improvement. If the skin does not deteriorate further, you can try to use one of the products alone to determine whether the problem is caused by the interaction between them. You can also consult a professional dermatologist or beautician and give more specific suggestions according to your specific situation.

Please note that everyone's skin condition and needs are different, and the skin care products suitable for them will be different. It is recommended that you carefully read the product description when purchasing skin care products and choose products suitable for your skin and needs. I hope my answer can help you. If you have any other questions, please feel free to ask me.