What causes mucus symptoms?

Mucus symptoms, such as runny nose and nasal congestion, are most commonly due to allergies or the common cold. Bacterial, viral and fungal infections leading to sinusitis, bronchitis or pneumonia can also cause mucus symptoms of the respiratory system.

Many different gastrointestinal conditions and diseases also cause mucus symptoms, such as inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis; food allergies; food poisoning; or infections affecting the digestive tract.

Respiratory system causes of mucus symptoms

Mucus symptoms may be caused by conditions affecting the respiratory system including:

  • Asthma and allergies
  • Bacterial infections
  • Bronchitis
  • Common cold (viral respiratory infection)
  • Cystic fibrosis
  • Hay fever or allergic reaction from animal dander, dust, cosmetics, or pollen
  • Influenza (flu)
  • Sinusitis (inflammation or infection of the sinuses)

Gastrointestinal causes of mucus symptoms

Mucus symptoms can also be caused by the gastrointestinal system including:

  • Bacterial gastrointestinal infection, such as Salmonella food poisoning, Campylobacter infection, or traveler’s diarrhea
  • Cystic fibrosis
  • Dysentery (infectious inflammation of the colon causing severe bloody diarrhea)
  • Food allergies (allergic reaction to certain foods)
  • Food intolerances (difficulty digesting certain foods without symptoms of a food allergy)
  • Food poisoning
  • Inflammatory bowel disease (includes Crohn’s disease and ulcerative colitis)
  • Irritable bowel syndrome (IBS; digestive discomfort that does not cause intestinal damage or serious disease)
  • Parasitic infection of the gastrointestinal tract
  • Viral gastroenteritis (viral infection of the digestive tract, also called stomach flu or intestinal flu)

Serious or life-threatening causes of mucus symptoms

In some cases, mucus symptoms may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

  • Cholera (infection of the small intestine causing watery diarrhea and vomiting)
  • Pneumonia

Questions for diagnosing the cause of mucus symptoms

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your mucus symptoms including:

  • Do any other family members have the same problem?
  • Do you have any other symptoms?
  • How long have you had your mucus symptoms?
  • What medications are you taking?

What are the potential complications of mucus symptoms?

Because mucus symptoms can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Dehydration and electrolyte imbalance due to long-term diarrhea
  • Hypoxia (low levels of oxygen in the blood)
  • Pneumonia
  • Respiratory failure and respiratory arrest
  • Spread of infection


  1. Diarrhea. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003126.htm.
  2. Cough. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003072.htm.
  3. Pillarisetti N, Williamson E, Linnane B, et al. Infection, inflammation, and lung function decline in infants with cystic fibrosis. Am J Respir Crit Care Med 2011; 184:75.

What are the signs of mucus problems?

Mucus symptoms occur when the membranes lining the respiratory and digestive tracts produce excess mucus, often in response to an irritant or allergen, resulting in congestion, breathing difficulties, or diarrhea. It represents the body’s normal response to an uninvited irritant.

Mucus symptoms, such as runny nose and nasal congestion, are most commonly due to Read more about mucus symptomsintroduction


What other symptoms might occur with mucus symptoms?

Mucus symptoms may accompany other symptoms that vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the mucous membranes may also involve other body systems.

Respiratory symptoms that may occur along with mucus symptoms

Mucus symptoms may accompany other symptoms affecting the respiratory system including:

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Sep 6, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Digestive System

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