When a baby has a cold, a change from clear mucus to purulent discharge may be a natural process of the immune system eliminating bacteria and toxins under medication. It’s advisable to continue observing, keep the baby well-hydrated, and seek further medical examination if necessary.
Children usually have clear nasal mucus at the beginning of a cold, which may turn yellow as the condition progresses. This could be due to an immune response to a viral infection or a worsening of symptoms caused by a secondary bacterial infection.
If a child experiences cold symptoms after receiving the MMR vaccine, it might be due to a wind-cold cold. It’s advised to take appropriate medication and drink plenty of water.