Does a child need antibiotics for a cold or green mucus?
Colds are usually viral, so antibiotics do not treat them. Mucus colour alone does not establish a bacterial infection. Antibiotics are used when a clinician identifies a bacterial illness or complication, rather than simply because a runny nose lasts several days.
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What helps instead?
Continue age-appropriate feeds or fluids. Saline nose drops and measures for discomfort may help when used with age- and weight-appropriate advice. Do not use combination cold and cough medicines for young children without guidance, and never give leftover antibiotics from an earlier prescription.
Watch the course of illness
Arrange assessment if a child worsens after improving, has symptoms that fail to improve, develops persistent fever or has a new localised pain. This does not automatically mean antibiotics are needed; examination may point to another explanation or treatment.
When not to wait
Breathing difficulty, marked lethargy or reduced drinking and urine output needs urgent attention. Fever in a baby under three months requires urgent medical assessment even if the illness appears to be a mild cold. Do not wait for a set number of days when warning signs are present.
Related reading: Is a throat swab or a blood test used to diagnose strep throat?.