An Overview of Bronchorrhea

Bronchorrhea is defined as an excessive discharge of watery mucus from the lungs, which results in a productive cough. This discharge is more copious than normal phlegm, and by definition occurs only when a person coughs up at least the equivalent of 20 teaspoons (100 cubic centimeters [cc]) of mucus daily from their lungs. Lung cancer is a common cause, but it may be caused by benign conditions such as bronchitis and bronchiectasis as well. Treatments may decrease the amount of mucus, but addressing the underlying cause is important.

An older man with bad cough at the doctor's office
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Bronchorrhea is a symptom in which large amounts of thin mucus are coughed up from a person's lungs on a daily basis. This is not just a little drainage and can be an incredibly distressing symptom. Bronchorrhea tends to be at its worst in the morning and often improves throughout the day.

This symptom can result in a persistent cough (to clear the fluid) and shortness of breath (due to obstruction of the airways by mucus). Since many of the conditions that cause bronchorrhea can also result in a cough and shortness of breath, bronchorrhea can aggravate those symptoms tremendously.


While bronchorrhea is mostly a nuisance (though often very dramatic), it may result in abnormalities in the body's electrolytes and dehydration. When severe, it may also result in obstruction of the airways and respiratory distress.


Evaluation for bronchorrhea is usually performed by taking a careful medical history and physical exam. That said, imaging studies and blood work are usually done as part of the work-up. Testings and procedures may include:

  • Imaging: Such as chest CT, MRI, or PET
  • Tuberculosis testing
  • Pulmonary function tests

The precise definition of bronchorrhea is the production of more than 100 cc (more than 20 teaspoons) of mucous daily.


There are several causes of bronchorrhea, though thankfully it is a fairly uncommon condition. Possible causes include:

Lung Diseases

Chronic bronchitis is a form of chronic obstructive pulmonary disease (COPD) characterized by inflammation of the bronchi.

Bronchiectasis is an obstructive lung disease often caused by childhood respiratory infections, which results in mucus collection in the airways due to widening and dilation of the airways.

Asthma, especially cough-variant asthma: Cough-variant asthma is an atypical form of asthma in which the only symptom at the time of diagnosis is a cough.

Lung Cancer

A form of lung cancer which in the past was called mucinous bronchioloalveolar carcinoma (BAC), is the most common cause of bronchorrhea. BAC has now been reclassified as a form of lung adenocarcinoma, but still causes this bothersome drainage for people living with the new diagnosis. With BAC, the incidence of bronchorrhea is estimated to be around 6%.


Tuberculosis has been associated with bronchorrhea, though this is less common in the United States.

Poisonings and Stings

Poisoning with chemicals known as organophosphates (anticholinesterase pesticides) is a serious cause of bronchorrhea. Scorpion stings may also be responsible.


The best treatment for bronchorrhea is to find and treat the underlying cause, especially with lung cancer, and to understand the mechanism by which it occurs.


To understand the best treatment options it's important to note that bronchorrhea is different than coughing up phlegm. It's believed that for some reason the airways become hyperresponsive to a particular stressor. This differs from mucous production associated with many lung conditions that is a result of inflammation, and because of this, many traditional treatments for excess phlegm are ineffective.

Treatments for Symptoms

Several different treatment options have been tried in an effort to reduce the symptoms of bronchorrhea. While these appear to give only moderate relief, steroids and non-steroidal anti-inflammatory inhalers (inhaled indomethocin) or a class of antibiotics known as macrolide antibiotics (Biaxin, Zithromax) may be of some benefit. The man-made hormone octreotide may also be helpful for some people.

Inhaled indomethacin can take quite a while to work, but has the potential to help over the long term.

Tryosine kinase inhibitors such as those used for EGFR positive lung cancer have been very effective in some cases, and it's thought that this benefit is unrelated to the effect the drugs have on reducing the size of the cancer (they work much faster than would be expected if the effect was due to a decrease in size of the tumor). Other evidence of an independent action is that the medication Iressa (gefitinib) worked well for one patient, even though he later tested negative for an EGFR mutation.

A promising clinical trials is in place using a medication that results in the inhibition of myristoylated alanine-rich C-kinase substrate.

A Word From Verywell

Bronchorrhea is a relatively uncommon symptom in which large amounts of a watery discharge are coughed up from the lungs. It may occur with lung cancer, particularly some types, as well as other lung conditions. Since lung adenocarcinoma appears to be increasing, especially in young adults with lung cancer and people who have never smoked, it's likely that this symptom will be on the rise.

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  1. Remi C, Remi J, Bausewein C. Pharmacological Management of Bronchorrhea in Malignant Disease: A Systematic Literature Review. Journal of Pain and Symptom Management. 2016. 51(5):916-25. doi:10.1016/j.jpainsymman.2015.12.335

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