Should You Spit or Swallow Phlegm? Understanding the Best Approach

Phlegm, also known as sputum, is the thick, sticky mucus produced in the lungs and respiratory passages. It plays a vital role in protecting our airways by trapping bacteria, viruses, allergens, and dust through its mucin components—large proteins coated with sugars that help regulate immune responses.

During illnesses, especially in winter with viral infections, there's often an excess of phlegm. Conditions like asthma, allergies, bacterial infections, smoking, and air pollution also increase mucus production. Interestingly, even in health, our lungs constantly produce mucus to keep airway surfaces moist and trap potential irritants. When the immune system detects a threat, it signals mucus-producing cells to increase mucus secretion, which is then cleared by tiny hair-like structures called cilia that move the mucus up to the throat to be coughed out or swallowed.

A common question many have is whether it’s better to spit out or swallow phlegm when dealing with respiratory issues. Both options are generally safe, but they serve different practical purposes.

Spitting Phlegm can be helpful if the mucus is thick, sticky, or irritating the throat. It also allows you to observe any abnormalities, such as blood, which could indicate serious conditions like tuberculosis or cancer. When spitting, it’s important to do so into a tissue and dispose of it properly, followed by handwashing to prevent infection spread. However, for many people, spitting may be inconvenient or considered impolite. It also isn’t necessary for recovery, especially as most viral infections resolve with time regardless of whether the mucus is spit out.

Swallowing Phlegm is a completely normal and harmless process. The body produces about 50 milliliters of mucus daily, which we typically swallow unconsciously. This mucus is passed into the stomach, where digestive acids and enzymes break it down, including any germs present. Swallowing does not cause reinfection or spread. Interestingly, this process may even bolster immunity, as immune cells in the gut learn to recognize viruses, helping the body prepare for future encounters. Vaccines like the oral polio vaccine utilize this natural mechanism.

Ultimately, whether you choose to spit or swallow your phlegm depends on personal comfort. For most healthy individuals, swallowing is perfectly fine and convenient, especially for young children who cannot spit effectively. If you're coughing up thick mucus that bothers you, spitting might offer some relief. In the end, both methods are safe, and the choice is a matter of what feels right for you during respiratory illnesses.

Source: https://medicalxpress.com/news/2025-06-swallow-phlegm.html