Carbonated drinks are beverages infused with pressurized carbon dioxide gas, which creates the characteristic fizz. These drinks can trigger coughing through two distinct pathways. The reaction can be an immediate, acute reflex during consumption, or it can contribute to a chronic, persistent cough over time.
Immediate Coughing: The Physical Mechanism of Fizz
The acute coughing reflex is caused by more than just the physical popping of bubbles. Carbon dioxide (CO2) dissolved in the liquid interacts with water and the enzyme carbonic anhydrase in saliva. This chemical reaction rapidly converts the CO2 into carbonic acid, an acidic compound.
This sudden acidification in the mouth and throat activates sensory nerves, specifically pain receptors in the mucosal lining of the pharynx and larynx. The resulting stinging or tickling feeling is interpreted by the body as an irritant. This immediate irritation triggers a protective cough reflex. The mechanical pressure of the expanding bubbles, combined with the chemical irritation from the newly formed acid, creates a dual stimulus that causes involuntary coughing.
Acid Reflux and Chronic Coughing
A link between carbonated drinks and a persistent cough often involves acid reflux and the digestive system. Carbonated beverages are highly acidic due to carbonic acid and added acids like phosphoric or citric acid, often resulting in a pH of 2.5 to 3.5. This acidity can compromise the lower esophageal sphincter (LES), the muscle barrier between the esophagus and the stomach.
Ingesting these drinks causes the stomach to distend due to the rapid release of carbon dioxide gas. This gastric distention increases the frequency of transient LES relaxations (tLESRs). These temporary relaxations allow stomach contents, including acidic digestive juices, to flow backward into the esophagus, a process known as gastroesophageal reflux (GER).
The refluxed stomach acid irritates the delicate lining of the esophagus, causing gastroesophageal reflux disease (GERD). If the acid travels further up into the throat and voice box, it is called Laryngopharyngeal Reflux (LPR). This refluxate irritates the sensitive tissues of the larynx and pharynx, leading to a persistent, often dry, cough. This cough is a secondary symptom of the underlying irritation, often delayed after consumption, and serves as the body’s attempt to clear the upper airway.
Other Ingredients That May Trigger Coughing
Beyond carbonation and acidity, other compounds in fizzy drinks can exacerbate coughing symptoms. Caffeine, common in colas, is a known stimulant that affects the gastrointestinal system. Like carbonation, caffeine can decrease the pressure of the lower esophageal sphincter, increasing the risk of acid reflux that leads to a cough.
The high concentration of refined sugars or artificial sweeteners may also contribute to throat irritation. Some sweeteners or food dyes may trigger minor allergic or sensitivity reactions in the throat and airway. While these ingredients do not directly cause a cough, they can make the throat more sensitive to irritation, potentially worsening a cough already triggered by other means.
When to Seek Medical Guidance
While an immediate cough after a carbonated drink is usually a harmless reflex, a persistent cough lasting several weeks warrants medical attention. A cough that continues for eight weeks or more in adults is considered chronic and should be evaluated to determine the underlying cause. Tracking symptoms can be helpful, especially noting if the cough is accompanied by other concerning signs.
You should consult a doctor if the cough occurs with wheezing, shortness of breath, chest pain, or difficulty swallowing. Prompt medical care is necessary if you are coughing up blood or thick, discolored phlegm, or if the cough is accompanied by unexplained weight loss or fever. These symptoms may indicate a condition more serious than simple beverage irritation, such as severe GERD, asthma, or a respiratory infection.