What is wrong with the fingernails turning black and blue?

Patient's question:

Please ask the doctor, the nails of our newborn doll are black and blue, what's going on? Thank you

Doctor's answer:

Fingernails turning blue are often due to weak qi and blood, qi stagnation and blood stasis, or internal cold.
1. If it is caused by taking overly cold medications that damage yang qi or obstruct its generation, it will gradually recover after stopping the medication. If you have experienced chest tightness, shortness of breath, palpitations, or aversion to cold in the past, although there may not necessarily be a structural abnormality, it is best to undergo relevant heart examinations. Daily suggestions include getting more rest and drinking more water.