Why Are You Coughing Up Gray Mucus or Phlegm?

Key takeaways:

• Coughing up gray mucus or phlegm can be a temporary symptom of an infection or allergies; it may also be a reaction to chemicals or smoke in the environment.
• Home remedies and over-the-counter medications can reduce or eliminate most cases of coughing up gray mucus without the need for medical attention.
• If you’ve been coughing up gray mucus or phlegm for weeks, you may have a lung condition; consult a doctor as soon as possible.

Many people use the terms "mucus," "phlegm," and "snot" interchangeably, thinking they refer to the same substance. However, "mucus" and "phlegm" are generally more acceptable than "snot," which often carries a negative connotation – especially when used to describe someone as arrogant or obnoxious.

It’s important to understand the differences between mucus and phlegm. Mucus is typically clear and serves as a protective barrier in your nose, throat, and airways. Phlegm is a type of mucus that’s usually associated with medical conditions; it can be thick and may contain viruses, bacteria, or other debris.

There are different causes of excess mucus and phlegm and various ways of treating it. It could, for instance, be an early sign of infection or a response to inhaling smoke or other irritants. This article covers questions about coughing up gray mucus and phlegm and related symptoms.

Is coughing up gray mucus or phlegm normal?

Occasional coughing is absolutely normal; it’s a natural reflex that helps clear the throat and airways. When coughing becomes persistent, however, or you’re coughing up gray mucus or phlegm, it could be a warning sign. Maybe it even draws attention from those around you who fear that you’re contagious – and they could be right.

Causes of coughing up gray mucus

Phlegm’s characteristics, such as its color and consistency, can be normal or may indicate a medical condition. Clear, white, or gray mucus can offer valuable insights for your diagnosis and treatment by a healthcare provider. However, the color of the mucus is not always an accurate indicator of its underlying cause.

Infections

Coughing up gray mucus or phlegm can indicate a bacterial, viral, or fungal infection. The most common cause is viral bronchitis, which is inflammation of the airways. COVID-19 is one example of an infection that may lead to coughing up gray mucus, along with symptoms like breathing difficulties, fever, pain, and diarrhea. Other illnesses, like the common cold, flu, or pneumonia, can also produce gray mucus.

Environmental irritants and allergies

Smoking or being around smokers is an example of an environmental irritant that can lead to coughing up gray mucus. Smokers are at risk of developing several medical conditions. These include chronic bronchitis, chronic obstructive pulmonary disease (COPD), emphysema, and lung cancer. Air pollution can also contribute to the production of gray mucus, especially if you suffer from allergies or asthma.

Lung disease

If you cough up gray mucus, a lung condition might be causing it. Chronic lung diseases, such as chronic bronchitis, COPD, emphysema, and bronchiectasis, can damage your airways and produce gray mucus. If you suffer from one of those lung diseases, your lungs may be unable to clear foreign substances or bacteria.

Cancer

Coughing up gray mucus is not typically a sign of lung cancer. Still, it’s wise to talk to your doctor if you experience this symptom. The term “gray” can be somewhat ambiguous. If the gray mucus appears sticky or has a brownish tinge, it may be a warning sign that warrants medical evaluation.

Other causes of coughing up gray mucus based on the mucus’s appearance or other symptom or situation

Along with coughing up gray mucus or phlegm, you may also have other symptoms. For instance, you could be having some trouble breathing or are coughing persistently. These symptoms can help identify the underlying cause and determine the best treatment for you.

Coughing up thick gray phlegm

If you are coughing up thick, gray phlegm, there could be several reasons for it:

• Airborne irritants such as dust, grime, or smoke
• An early sign of infection
  • Common cold
  • Flu
  • Viral bronchitis
  • Sinusitis (sinus infection)

Coughing up green and gray phlegm

If you are coughing up green or gray phlegm, you may have a viral or bacterial infection. This is often because your mucus contains a buildup of white blood cells. These white blood cells produce an enzyme that’s a green color due to its iron content.

Coughing up brown and gray phlegm

If you’re coughing up brown and gray phlegm, you could have a lung infection such as pneumonia or bronchitis. You may also have symptoms like fever, sore throat, runny or stuffy nose, muscle aches, and headache. If you’re a smoker, smoking can also cause you to cough up brown and gray phlegm.

Coughing up gray phlegm in the morning only

It’s common for people to occasionally wake up with nasal or throat congestion. This is usually normal, especially if it improves as the day goes by. Coughing up gray mucus in the morning might be caused by several factors, including:

• Postnasal drainage
• Sinusitis
• Viral bronchitis
• Irritants such as dust, mold, smoke, or chemicals
• Rare fungal infection

Coughing up gray phlegm after smoking

Smoking is a major cause of coughing up phlegm. Smoking contributes to the build-up of tar and other chemicals in mucus, which can result in a dark or gray discoloration. Additionally, smoking can hinder your lungs' natural ability to clear away mucus and lead to long-term breathing problems.

Coughing up gray phlegm after quitting smoking

After quitting smoking, your airways and lungs may still have difficulty clearing mucus effectively. You might notice an increase in gray phlegm shortly after stopping, but this should gradually decrease over time. This occurs because tobacco smoke can paralyze or damage the tiny hair-like cells in your airways. If you don't resume smoking, your airways and lungs can gradually regain their ability to function normally. (Note: Although vaping may seem like a safer alternative, that is not the case; it can cause similar lung problems.)

Coughing up gray phlegm while sick with a cold or the flu

When you have a cold or the flu, coughing up clear or gray phlegm is common. You may also cough up phlegm that’s yellow or greenish-yellow. If this coughing doesn't improve within a few days, it's a good idea to consult a medical professional for advice. Depending on your diagnosis, you may also receive a prescription for antibiotics or other medication.

Diagnosing coughing up gray mucus

Your doctor will ask you several detailed questions, including information about your smoking history and recent exposure to environmental allergens or toxins. Then, you’ll have a detailed physical exam, including listening to your heart and lungs with a stethoscope. Your doctor may also order blood tests, phlegm cultures, breathing tests, and X-rays.

Treatment options for coughing up gray mucus

The goal of treatment is to clear up whatever is causing you to cough up gray mucus. Improving your breathing may also be necessary, which will involve rest and hydration.

At-home remedies

• Rest
• Drinking water or hot liquids such as herbal teas, soups, or coffee
• Honey and lemon
• Over-the-counter cough medicines
  • Expectorants (such as guaifenesin) that thin mucus
  • Cough suppressants or antitussives such as dextromethorphan
  • Combination medicines and pain relievers like Tylenol or ibuprofen
• Grapes may contain natural expectorants
• Elderberry may help shorten the cough duration
• Probiotics and bromelain supplements may be beneficial, but more research needs to be done on their effectiveness.

Steam, hot showers

Breathing in warm, humidified air may help clear gray mucus from your throat and lungs. Another option is to make a steam bowl of hot water and lean over it, breathing in the steam.

Salt water gargle

Mixing 1/4 to 1/2 teaspoon of salt in 8 ounces of warm water and using it as a gargle may help soothe a sore throat and cough caused by gray mucus. (Be sure not to swallow the salt water, especially if you suffer from heart disease or high blood pressure.)

When you should see a doctor about coughing up gray mucus

If your bout with coughing up gray mucus does not subside after a few days, you may need to seek the advice of a medical professional.

Symptoms that mean you should see a doctor:

• Fever over 1010 F
• Sore throat
• Runny or stuffy nose
• Headaches
• Muscle aches
• Extreme fatigue
• Difficulty swallowing or breathing
• Making unusual noises when breathing

Symptoms that mean you should go to the emergency room:

• Chest pain
• Difficulty swallowing or breathing
• Making unusual noises when breathing
• High fever or low temperature
• Rapid breathing or heart rate
• Loss of voice
• Confusion or disorientation

Questions to ask your doctor about coughing up gray mucus

• Am I contagious?
• How serious is my coughing up gray mucus?
• What is a normal amount of gray mucus to have?
• Is it a good idea for me to suppress my cough?
• Why am I having chest pain when coughing up mucus?
• What types of tests do I need?
• Do I need a chest X-ray or CT scan?
• Why am I having night sweats?

Frequently asked questions: coughing up gray mucus

If you’ve been coughing up gray mucus, you may have more specific questions for your doctor. Asking these questions could help determine the best treatment for you.

Is coughing up gray mucus a sign or symptom of COVID?

Although coughing is a common symptom of COVID-19, the color of mucus may not be very helpful in diagnosing the illness. You might be coughing up mucus that’s green, yellow, or gray. It’s crucial to get tested for COVID-19 if you’re coughing up mucus and also have additional symptoms like a low-grade fever, muscle aches, nasal congestion, loss of appetite, and loss of taste or smell.

What if you’re coughing up gray mucus but feel fine otherwise?

Coughing up gray mucus can be normal, especially if you’re recovering from a cold or dealing with allergies or hay fever. However, it’s important to seek medical attention if the gray mucus persists for more than a few days or a week at the most. This could indicate an underlying medical condition that needs to be addressed.

What if you have been coughing up gray mucus for a week or longer?

If you’ve been coughing up gray mucus for a week or longer, it could mean you have an underlying condition. This could be an infection, allergies, lung disease, smoking, or even gastroesophageal reflux (acid reflux). It’s important to consult a medical professional who can assess your situation and determine the appropriate treatment.

Heed your symptoms

If you’re coughing up gray mucus or phlegm, there could be various reasons for it. Most causes are not serious and can be treated with supportive care and home remedies without the need to see a doctor. But as this article explains, there are situations when you’ll want to seek medical care. Pay attention to your symptoms and make the choices that are best for you.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Pallabi Sanyal-Dey, MD.

Sources

Knutson, Doug, and Chad Braun, “Diagnosis and Management of Acute Bronchitis,” American Family Physician, May 15, 2002. www.aafp.org/pubs/afp/issues/2002/0515/p2039.html.

Sethi, Sanjay, and Timothy F Murphy, “Infection in the Pathogenesis and Course of Chronic Obstructive Pulmonary Disease,” The New England Journal of Medicine, November 27, 2008. www.nejm.org/doi/abs/10.1056/NEJMra0800353.

Wenzel, Richard P, and Alpha A Fowler 3rd, “Clinical Practice. Acute Bronchitis.” The New England Journal of Medicine, November 16, 2006. www.nejm.org/doi/10.1056/NEJMcp061493?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed.