Is it harmful to swallow phlegm when coughing?

Sep 16, 2025 Source: Cainiu Health

Dr. Ren Yi

Introduction

Sputum is secreted by the mucous membranes of the respiratory tract. Under healthy conditions, it is produced in small amounts and has a simple composition. When swallowed, it enters the digestive tract where it is broken down by gastric acid, causing no burden to the body. In such cases, there is no need to deliberately avoid swallowing sputum. However, when there is an infection or pathology in the respiratory tract, the sputum may contain large amounts of bacteria, viruses, or inflammatory secretions. Swallowing sputum under these circumstances may increase the risk of gastrointestinal infection.

Under normal circumstances, occasionally swallowing a small amount of phlegm does not cause significant harm to healthy individuals. However, if phlegm increases abnormally in volume, changes color, or is accompanied by other discomforts, it should not be swallowed. Detailed analysis is as follows:

Phlegm is secreted by the respiratory mucosa. In healthy conditions, the amount is small and its composition is simple. Once swallowed, it enters the digestive tract where it is broken down by gastric acid and does not impose a burden on the body. In such cases, there is no need to deliberately avoid swallowing phlegm.

When there is a respiratory infection or pathological change, phlegm may contain large numbers of bacteria, viruses, or inflammatory secretions. Swallowing such phlegm increases the risk of gastrointestinal infection, and could lead to the spread of pathogens. This is especially dangerous for individuals with weakened immune systems. In these cases, phlegm should not be swallowed.

In daily life, pay attention to changes in the characteristics of phlegm. If you notice yellow or green discoloration, blood-tinged sputum, or accompanying symptoms such as fever or chest pain, seek medical evaluation promptly.

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What are the reasons for a persistent cough, and how can it be treated?

In general, persistent coughing may be caused by ongoing environmental irritation, low immune function, allergic cough, prolonged acute bronchitis, gastroesophageal reflux disease (GERD), or other reasons. It is recommended to seek medical attention promptly, identify the underlying cause, and then improve symptoms through general measures, medication, or other treatments under a doctor's guidance. In daily life, avoid smoking and secondhand smoke, and limit consumption of spicy or overly sweet foods.

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What are the differences between cough caused by mycoplasma infection and common cough?

The differences between cough caused by mycoplasma infection and ordinary cough mainly include duration, nature of the cough, accompanying symptoms, triggering factors, and response to treatment. In daily life, it is important to stay warm, avoid cold exposure, maintain good indoor ventilation, and reduce visits to crowded places. During episodes of coughing, drink plenty of warm water and avoid spicy or irritating foods to help alleviate cough symptoms.