Why Are You Coughing Up Clear Mucus or Phlegm Mean?

Key takeaways:

• Most causes of coughing up clear mucus are benign.
• Clear mucus may just be your body’s natural response to an irritant in the respiratory tract.
• Clear mucus that is foamy or frothy should warrant emergency evaluation.

Clear mucus is typically produced by your respiratory system in response to irritants such as allergens, chemicals, or infections. Most causes will resolve naturally on their own, but there are a few instances that would warrant a visit to your doctor. This article will explore the most common causes of coughing up clear mucus, when to take this symptom more seriously, and what you can do to relieve the symptom.

Is coughing up clear mucus or phlegm normal?

Coughing up clear mucus or phlegm is a common occurrence and often happens when your body is trying to clear irritants or infections from your airways. Many times, it is normal.

Causes of coughing up clear mucus

Clear mucus can stem from several different triggers. Luckily, most of them are minor, easily treatable, and rarely life-threatening.

Infection

There is a long-standing myth that green or yellow mucus equates to an infection. However, researchers have debunked this myth, revealing that the color of your mucus does not always indicate an infection, and it is possible to have a bacterial or viral lung infection and cough up clear mucus. Even if your mucus is clear, if you are experiencing additional symptoms such as fever, body aches, sore throat, or sinus congestion, you should consider a respiratory tract infection as a possible cause of your symptoms.

Airway irritation

Airway irritation can lead to inflammation and mucus production from within the lungs. This mucus is often clear and may be accompanied by a cough. Common examples of airway irritants include cigarette smoke and chemicals.

GERD

Gastroesophageal reflux disease (GERD), more commonly referred to as acid reflux or heartburn may be the culprit behind your cough. Studies show that anywhere from 10-59% of causes of chronic coughs (meaning coughs that last longer than 8 weeks) are actually a symptom of GERD. GERD can lead to the secretion of mucus in the respiratory tract causing a cough productive of clear phlegm.

Post-nasal drip

Post-nasal drip occurs when excess mucus from the nasal passages drips down the back of the throat. The irritation from the mucus running down the throat can trigger coughing. This can be caused by upper respiratory infections, sinus infections, allergies, and chronic sinus conditions.

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

Coughing up clear mucus is often benign and the result of many different underlying causes. But to narrow down the potential cause, you should examine other aspects of the mucus.

Coughing up thick clear mucus

Thick, clear mucus is often seen in individuals with sinus congestion or post-nasal drip. When mucus stays in the nasal passages or sinuses for a longer period, it thickens. As it drips down the back of the throat, it can trigger a cough. This can also be the result of a respiratory infection or a chronic respiratory condition.

Coughing up bubbly or foamy clear mucus

Coughing up bubbly or foamy mucus should alert you to something serious going on known as pulmonary edema, or fluid in the lungs. If left untreated, fluid in the lungs can lead to respiratory failure. Frothy sputum is a hallmark sign of this and should be evaluated immediately.

Coughing up clear yellow mucus

As previously mentioned, the color of mucus does not always indicate an infection like previously thought. Yellow mucus can be seen in cases of infection, but it may also occur with acid reflux or bile reflux.

Coughing up clear green mucus

When an irritant comes in contact with your airways (including infections, chemicals, and smoke), your body will produce an enzyme to try and fight off the irritant. This enzyme is known to cause a reaction that turns the sputum green.

Coughing up clear mucus with blood

Occasionally, clear mucus may contain small amounts of blood. This can be a result of irritation and inflammation in the airways due to coughing or infection. If blood persists for more than a few days or is noted in large amounts, you should see your healthcare provider as soon as possible.

Coughing up clear mucus after surgery

To some extent, it is normal to cough up clear mucus after surgery, especially after procedures that involve the lungs. In fact, it is important to cough out mucus after surgery because allowing it to sit in your lungs for extended periods of time can lead to post-surgical lung infections. If you are experiencing fever or shortness of breath, a post-surgical blood clot or lung infection should be ruled out.

Coughing up clear mucus when you have GERD

As highlighted above, GERD can be the cause of coughing up clear mucus. If you are experiencing a chronic cough and do not have any additional symptoms indicating that you have an infection, you should consider GERD as a potential cause.

Coughing up orange mucus in the morning only

Mucus that is orange to brown in color usually indicates the presence of dried blood. If you are coughing up orange mucus only in the morning, it may be the result of post-nasal drip accumulation in the back of the throat overnight.

Diagnosing coughing up clear mucus

There are several different diagnostic studies your healthcare provider may use to identify the cause of your symptoms. A chest x-ray or a CT scan of the chest are typically the first tests ordered because they are non-invasive and inexpensive. If these studies are not helpful, they may perform an analysis of the phlegm or a bronchoscopy to look directly into your lungs.

Treatment options for coughing up clear mucus

Treatment for coughing up clear mucus depends on the underlying cause. Below are some common approaches to try either at home or with the guidance of your healthcare provider.

At-home remedies

Many causes of clear mucus can be managed at home. Rest, increasing hydration, and using a humidifier to reduce inflammation in the airways are all helpful steps to try.

Medications

There are multiple different types of medication that might be useful for this symptom depending on the cause. If you are diagnosed with a bacterial infection, your doctor may prescribe an antibiotic. If you have post-nasal drip, prescription nasal sprays, decongestants, antihistamines, and even a short course of steroids may be beneficial. Acid-reducing medications can help in the setting of GERD.

Lifestyle changes

Some causes of chronic coughs that produce clear mucus can be managed with lifestyle changes. If your symptoms are caused by acid reflux, making dietary changes to avoid trigger foods can minimize symptoms. Chronic smokers tend to have a persistent cough, so if you do smoke, you should stop.

When you should see a doctor about coughing up clear mucus

Most cases of clear mucus will resolve on their own. However, some situations should prompt you to see a healthcare provider.

You should see a doctor if:

• The mucus production persists for more than a week.
• You experience other symptoms like fever, sinus pain, or sore throat.
• You have a history of chronic conditions, such as asthma, COPD, or GERD.

You should go to the emergency room if:

• You are coughing up foamy or frothy mucus.
• You are experiencing additional symptoms such as chest pain or shortness of breath.

Questions to ask your doctor about coughing up clear mucus

• What could be causing this symptom?
• Does this mean I need an antibiotic?
• How long should I expect my cough to last?
• What are some concerning red flag signs that I should look for?

Frequently asked questions: coughing up clear mucus

If you are coughing up clear mucus, especially for a prolonged period of time, you may have some questions for your healthcare provider. Here are some of the most commonly asked questions.

What does it mean when you cough up clear mucus but aren’t sick?

If you are coughing up clear mucus but are not sick, there is likely something non-infectious causing an irritation to your respiratory tract. This may include cigarette smoke, environmental chemical exposure, or post-nasal drip due to seasonal allergies. GERD should also be considered.

What if you’ve been coughing up clear mucus for a week or longer?

Due to the inflammation caused in the airways as a result of several different possible underlying factors, it is not uncommon for coughs to last up to 8 weeks. However, if you are coughing up clear mucus for more than a week, speaking with your doctor can help you narrow down the potential trigger and decide whether further action needs to be taken.

Conclusion

In most cases, coughing up clear mucus is simply your body’s natural response to clear the airways of minor irritants. While it is usually not a cause for concern, persistent or unusual changes in mucus such as color or consistency, or the presence of additional symptoms such as shortness of breath or fever should warrant further evaluation.

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. Jennifer Nadel, MD.

Sources

Malek, Ryan. and Shadi Soufi. “Pulmonary Edema.” StatPearls, StatPearls Publishing, 7 April 2023. https://pubmed.ncbi.nlm.nih.gov/32491543/

Nakajima, Takeo et al. “Retrospective Study of the Effects of Post-nasal Drip Symptoms on Cough Duration.” In vivo (Athens, Greece) vol. 35,3 (2021): 1799-1803. doi:10.21873/invivo.12440 https://pubmed.ncbi.nlm.nih.gov/33910865/

Shmerling, Robert. “Don’t Judge Your Mucus by Its Color - Harvard Health Blog.” Harvard Health Blog, 31 Jan. 2016, www.health.harvard.edu/blog/dont-judge-your-mucus-by-its-color-201602089129. Accessed 10 Nov. 2024.

Wu, Jiankang et al. “GERD-related chronic cough: Possible mechanism, diagnosis and treatment.” Frontiers in physiology vol. 13 1005404. 20 Oct. 2022, doi:10.3389/fphys.2022.1005404 https://pmc.ncbi.nlm.nih.gov/articles/PMC9630749/