Green mucus usually means your immune system is actively fighting something, often a respiratory infection like a cold, sinus infection, bronchitis, or pneumonia, but the color alone does not prove it is bacterial or that you need antibiotics.

Why mucus turns green

When germs irritate your airways or sinuses, your body sends white blood cells (especially neutrophils) to the area, and the enzymes and debris from these cells can give mucus a yellow or green color. Green often appears later in an illness or when there is a higher concentration of these cells and mucus has been sitting longer, such as first thing in the morning.

Common causes

Green mucus can show up with:

• Viral infections like the common cold or flu, which often start with clear or yellow mucus that may turn green as the immune response ramps up.

• Bacterial infections such as sinusitis, bronchitis, or pneumonia, where you may also have fever, facial pain, chest pain, or shortness of breath.

• Chronic lung conditions like COPD or cystic fibrosis, where persistent colored phlegm can signal a flare-up or infection.

Does green mean you need antibiotics?

Green mucus by itself does not reliably distinguish between viral and bacterial infection, and many people with green mucus do not have a bacterial infection that needs antibiotics. Decisions about antibiotics are usually based on how long symptoms have lasted, how severe they are, and other findings on examination, not just mucus color.

When to seek medical care

You should contact a clinician urgently or go to emergency care if green mucus comes with any of the following: trouble breathing, chest pain, high fever, confusion, or lips/fingertips turning blue. See a doctor within a few days if green mucus lasts more than about 10–12 days, keeps getting worse, or is accompanied by severe sinus pain, ear pain, or a cough producing large amounts of phlegm.

Simple self-care

If you otherwise feel fairly well, green mucus can often be managed at home with:

• Hydration and steam (showers, humidifier) to thin mucus.
• Saline nasal sprays or rinses to clear nasal passages.
• Over-the-counter pain/fever relievers and decongestants, used as directed.
  If you are unsure or have other health conditions (like asthma, COPD, or pregnancy), checking with a healthcare professional is recommended.