Something I thought about this week:
Flu season is hitting early this year with cases three times higher than this time last year.[1] I’ve started seeing an increasing number of patients with colds, coughs and fevers and one of the most common questions I get asked at this time of year is: “Does my green snot mean I need antibiotics?”
As I’m blowing my nose for the hundredth time, I have a lot of sympathy for this question today. The mucus in our nose, though frustrating when it’s pouring out, does have a useful purpose. It provides a protective coating for our nasal tract and helps catch irritants, bacteria and viruses. Green or yellow mucus is often due to the presence of your body’s white blood cells that are helping to fight infection. When invading bacteria or viruses arrive, the white cells engulf these infective agents and break them down. This breakdown leads to this yellow-green colour.[2]
Though the snot may look unsightly, this in itself doesn’t mean you need antibiotics. A cold should start improving on its own within 7 days, though this can be longer. It’s important to see a doctor if it is not improving, you have dark blood-stained mucus, any shortness of breath, persistent fevers or are feeling increasingly unwell.
[1] NHS England. Early flu wave could lead to ‘long and drawn out’ winter for NHS [Internet]. 30 Oct 2025 [cited 2025 Aug 29]. Available from: https://www.england.nhs.uk/2025/10/early-flu-wave-could-lead-to-long-and-drawn-out-winter-for-nhs/
[2] Patient.info. What your snot says about your health [Internet]. London: Patient Platform Limited; 2024 [cited 2025 Nov 5]. Available from: https://patient.info/features/ear-nose-throat/what-your-snot-says-about-your-health