Does Bright Yellow Mucous Mean You Need an Antibiotic?

Do you need an antibiotic if you’re blowing out bright yellow mucous? Find out what mucous color changes mean – and when you should be concerned.

When you blow bright yellow mucous out of your nose do you automatically run to the doctor for an antibiotic? Some people assume that bright yellow mucous is a sign of a bacterial infection – and that an antibiotic is the solution. This isn’t always the case. Overall, mucous color isn’t a reliable indicator of whether or not a person has a bacterial infection.

The mucous you blow out of your nose varies in color depending on your overall state of health and the humidity of the air around you. It’s not uncommon to blow out mucous in shades of yellow, green, and brown even in the absence of a bacterial infection. When you have a cold caused by a virus, infection fighting cells move into the area to fight off the infection. These infection fighting immune cells secrete proteins that alter mucous color – causing clear mucous to turn funny shades of yellow and green.  

Bright yellow mucous or mucous that’s red or brown in color comes from working in an area where the humidity is low. Dry, irritated nasal passages are more prone to bleeding which causes mucous discoloration. The solution is to get a humidifier and run it as often as possible throughout the day and night. Picking the nose also causes bleeding which can darken mucous.  

If you have allergies or allergic rhinitis, you may start out with a clear mucous that changes to a thick, bright yellow mucous – especially when allergies become chronic. Second generation antihistamines usually reduce mucous production by blocking the effects of histamine, but they won’t help the nasal discharge from a sinus infection.

How do you know when you need to see a doctor for yellow mucous? If bright yellow mucous comes from a bacterial sinus infection you’ll usually have other symptoms such as a headache and head pressure, fever, a bad taste in the mouth, or facial pain. Not all sinus infections are caused by bacteria, but when these symptoms are severe, it may be necessary to take an antibiotic to treat a possible bacterial infection – under the care of a doctor, of course.

The bottom line? Blowing bright yellow mucous out of your nose doesn’t automatically mean you need antibiotics. Viral infections, allergies, and low humidity are all possible causes for mucous color changes. On the other hand, if you have headache, fever, and facial pain, it’s a good idea to see a doctor.


Merck Manual. 18th Edition.

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