The Real Causes Behind Coughing

This article originally appeared on The Epoch Times and was republished with permission.

Guest post by Nathan Worcester

While coughing itself is not a disease, it is widely recognized as a symptom that is difficult to alleviate. Why do we sometimes cough persistently?

Coughing Cleanses Your Body

“Cough very much is a natural and protective thing; it protects our lungs,” Dr. Kian Fan Chung, a professor at the National Heart & Lung Institute at the Imperial College London, told The Epoch Times.

“It is a bit like a burglar alarm you have at home,” Dr. Chung said, conjuring a vivid analogy. “So if a burglar does go into your home, the alarm system goes up.”

The respiratory tract is abundant in nerve endings, some of which are known as cough receptors, located in the throat, vocal cords, and upper airway of the lungs. They react to foreign substances and stimuli; when activated, they trigger the cough reflex to expel mucus or foreign objects.

When we cough, we often gasp deeply, allowing air to penetrate the lungs. Following this, the glottis closes, covering the airway, while muscles in the chest and abdomen contract forcefully. At this point, air trapped in the airway cannot escape, resulting in significant intrathoracic pressure, typically exceeding 300 millimeters of mercury (mm/Hg). Finally, the glottis suddenly opens, causing air to rush out at speeds of up to 50 miles per hour, carrying mucus and foreign particles away from the airways.

During vigorous coughing, the air expulsion approaches the speed of sound.

Viral or bacterial infections, chemical toxins, inflammation, allergies, mucus in the nose, and stomach acid can all stimulate cough receptors. Moreover, apart from the respiratory tract, various sensory receptors are located in the ears, nose, stomach, pleura, pericardium, and other areas, all capable of triggering the coughing reflex.

Acute Coughs Are Typically Self-Resolving

Coughs are classified as one of three types based on the duration of symptoms: acute cough (lasting less than three weeks), subacute cough (lasting three to eight weeks), and chronic cough (lasting over eight weeks).

“An acute cough is really extremely common,” Dr. Paul Marik, chairman and chief scientific officer of the Front Line COVID-19 Critical Care Alliance (FLCCC) and former chief of the Division of Pulmonary and Critical Care Medicine at Eastern Virginia Medical School, told The Epoch Times. It happens mainly after an upper respiratory tract viral infection, including the common cold, flu, and COVID-19. The inflammation in the respiratory tract activates sensory receptors, thereby triggering coughing.

“In most patients who have acute cough, it’s the body’s natural response to infection and to get rid of the secretions,” he explained, noting that such symptoms typically resolve within a certain period.

Subacute coughs are also mainly caused by upper respiratory tract viral infections. This type of cough typically resolves on its own, with clinical data indicating that drug treatments often yield no significant benefits.

However, Dr. Marik highlighted that observing the characteristics of the secretions expelled during coughing is crucial. If these secretions are cloudy rather than clear, further examination is necessary to determine if there is a bacterial infection, such as bacterial bronchitis or bacterial sinusitis, both requiring antibiotic treatment.

Patients with pertussis also experience bouts of acute coughing. This is caused by a particular bacterium called Bordetella pertussis. Even adults who have received multiple doses of the pertussis vaccine can fall ill with the disease. The coughing sound in pertussis patients is distinctive, resembling a dog’s bark, which makes it easily recognizable. This is why it is also called whooping cough.

Dr. Marik emphasized the importance of taking measures for severe cases of acute and subacute coughing. Excessive coughing can potentially damage the throat and upper respiratory tract, leading to a vicious cycle of injury. Therefore, short-term oral corticosteroid medication may be necessary for more severe bouts of intermittent coughing.

He also mentioned a specific issue with acute COVID-19 infection: Patients infected with the virus often continue to cough even after recovering from discomfort and fatigue.

Dr. Chung stated that generally, “when the virus disappears, the cough disappears.” However, coughing caused by COVID-19 may persist for a long time. Based on his observations, 60 percent to 70 percent of individuals infected with COVID-19 experience prolonged coughing.

The precise reason for this phenomenon is still unknown. Dr. Marik speculated that it may be due to “persistent inflammation in the tracheobronchial tree that triggers the coughing.” Additionally, Dr. Chung explained that the COVID-19 virus triggers a hypersensitive state in cough receptors, which can persist for a long time, sometimes for several months.

Managing Acute Coughs

Many individuals often turn to cough suppressants when experiencing irritating coughs, but research has found that using such medications has minimal effect on coughs caused by viral infections.

The British Journal of General Practice published a systematic review and meta-analysis in 2018 that included 724 cases of patients with subacute cough following a viral infection across six randomized clinical trials. The findings concluded that no treatment regimen demonstrated clear benefits regarding cough recovery or other patient outcomes across all studies and meta-analyses assessing cough outcomes at 14 and 28 days.

Dr. Marik emphasized the importance of vitamin D supplementation, as the vitamin is crucial for the immune system. Additionally, zinc supplements should be considered. Some anti-inflammatory supplements “might be helpful, but the data is limited.”

He also shared a method for relieving coughing: adding inhalants containing menthol to boiling water and inhaling the steam that rises from it. These inhalants are readily available at pharmacies.

Menthol acts on the sensory nerves in the oral cavity and airways, generating a cooling sensation. Many cough syrups and lozenges contain menthol as a flavoring agent or active ingredient. Notably, animal studies have shown that menthol potentially possesses specific anti-tussive properties. Regulatory authorities such as the U.S. Food and Drug Administration (FDA) recognize this cough suppressant function.

Consuming honey or taking a hot bath may also be helpful for some people.

Persistent Cough

Coughing for one to four weeks is typically attributed to infections or irritants such as chemicals or smoke. “If it [lasts] more than eight weeks, then these other conditions need to be looked into,” Dr. Albert Rizzo, chief medical officer of the American Lung Association and clinical assistant professor of medicine at the Sidney Kimmel Medical College of Thomas Jefferson University, told The Epoch Times.

Chronic cough is the body’s way of trying to “get something out of the lungs [that’s] not supposed to be there,” said Dr. Rizzo.

First, ensuring that the cough is not caused by lung cancer, chronic lung infections, or pulmonary fibrosis is crucial, as these conditions are much more dangerous than others. Doctors will conduct examinations using chest X-rays or computed tomography (CT) scans.

A certain proportion of chronic coughs are caused by malignant diseases. A review published in 2023 showed that approximately 90 percent of chronic cough cases are nonmalignant conditions, with the remaining attributed to malignancies, including tumors. A systematic review and meta-analysis published in BMC Family Practice in 2021 revealed that the incidence of suspected cancer among patients with cough ranges from 0.2 percent to 1.8 percent.

Dr. Chung pointed out that cancer can induce a particular form of inflammation in the tissues, making the nerves more sensitive and thus more prone to coughing.

However, the causes of chronic cough are typically not life-threatening.

Read the full story at The Epoch Times.