Can Caffeine Cause Phlegm in the Throat? A Comprehensive Guide

December 21, 2025 •

4 min read

While not a direct cause, caffeine can exacerbate the conditions that lead to excessive phlegm in the throat. Its diuretic properties can cause dehydration, thickening mucus, while its effect on the esophageal sphincter can trigger acid reflux, leading to throat irritation. This article explores the relationship between caffeine and throat phlegm and outlines effective strategies to manage it.

Quick Summary

This guide details how caffeine can indirectly lead to increased phlegm in the throat by causing dehydration, which thickens mucus, and by relaxing the esophageal sphincter, triggering acid reflux. It provides insights into managing these symptoms through dietary adjustments and other lifestyle modifications to reduce throat irritation and excessive mucus.

Key Points

Indirect Cause: Caffeine doesn't directly cause phlegm but contributes to it indirectly through dehydration and acid reflux.
Dehydration Thickens Mucus: As a diuretic, caffeine can lead to fluid loss. This causes mucus to become thicker and stickier, creating the sensation of excess phlegm.
Acid Reflux Trigger: Caffeine can relax the lower esophageal sphincter, allowing stomach acid to irritate the throat and increase mucus production, a condition known as LPR.
Symptoms of LPR: The phlegm from LPR is often accompanied by frequent throat clearing, a persistent cough, and a feeling of a lump in the throat.
Management Strategies: Reducing caffeine, increasing water intake, adjusting coffee consumption habits, and managing acid reflux are key to alleviating symptoms.
Low-Acid Alternatives: Opting for low-acid coffees like cold brew or dark roasts, or switching to herbal tea, can be gentler on the throat.

How Caffeine Affects the Throat

Caffeine is a potent stimulant found in popular beverages like coffee, tea, and energy drinks. Its effects on the body are diverse, but when it comes to the throat, its impact is primarily indirect. The two main mechanisms by which caffeine can contribute to a sensation of phlegm are dehydration and acid reflux.

Dehydration and Thicker Mucus

Caffeine is a natural diuretic, meaning it increases urine production and can lead to fluid loss. For individuals with moderate intake, this effect is often minimal and easily compensated for by drinking enough water. However, for those who consume large amounts of caffeine or are already dehydrated, this can have a noticeable effect on mucous membranes. When the body becomes dehydrated, the mucus lining in the respiratory passages, including the throat, thickens and becomes stickier. This thickened mucus feels like a blockage or excess phlegm and becomes more difficult for the body to clear naturally. Staying properly hydrated is crucial to keeping mucus at the correct consistency for effective drainage.

Acid Reflux and Laryngopharyngeal Reflux (LPR)

Caffeine can relax the lower esophageal sphincter (LES), the muscle that acts as a valve between the esophagus and the stomach. When the LES relaxes, it can allow stomach acid to flow back up into the esophagus and, in some cases, all the way up to the throat and voice box (larynx). This condition is known as Laryngopharyngeal Reflux (LPR) or 'silent reflux,' because it doesn't always present with classic heartburn symptoms. The resulting irritation from stomach acid in the throat can cause an increased production of mucus as a protective measure, leading to the sensation of excess phlegm and the need for frequent throat clearing.

Comparison Table: Caffeine's Effects on Throat Phlegm


Aspect	Dehydration Impact	Acid Reflux Impact
Primary Mechanism	Increases urine output, leading to overall fluid loss.	Relaxes the lower esophageal sphincter, allowing stomach acid to rise.
Effect on Mucus	Thins the body's fluid content, resulting in thicker, stickier mucus.	Irritation from stomach acid triggers the body to produce more protective mucus.
Symptom Profile	Dry, thick feeling in the throat; difficult-to-clear mucus.	Frequent throat clearing, persistent cough, hoarseness, feeling of a 'lump'.
Contributing Factor	Insufficient water intake relative to caffeine consumption.	Drinking coffee on an empty stomach or consuming high-fat additives.

Managing Phlegm Caused by Caffeine

If you believe your coffee or tea habit is contributing to your throat phlegm, there are several steps you can take to manage or alleviate the symptoms.

Increase your water intake: The most direct way to counteract caffeine's diuretic effect is to drink more water. This will help keep your mucous membranes moist and your mucus thin and easy to clear. Some experts suggest sipping water frequently throughout the day, especially when consuming caffeinated beverages.
Reduce caffeine consumption: Consider cutting back on your overall caffeine intake or switching to decaffeinated options. Decaf coffee, while not entirely caffeine-free, contains significantly less caffeine and can still be a satisfying beverage choice. Herbal teas are another great non-caffeinated alternative.
Change your coffee habits: If you're unwilling to cut down, adjust how you drink it. Try a lower-acid option like cold brew, or opt for dark roasts, which tend to have lower acidity than lighter roasts. Avoid drinking coffee on an empty stomach, as this can amplify stomach acid production. Pairing your coffee with a meal can help buffer the effects.
Gargle with salt water: For immediate relief from throat irritation and to help clear residual mucus, gargling with a warm salt water solution can be very effective.
Use a humidifier: Keeping the air in your home moist, especially in your bedroom, can help soothe your nasal passages and throat, preventing the drying that can lead to thick mucus.
Elevate your head while sleeping: For those who experience LPR, sleeping with your head elevated can help prevent stomach acid from refluxing into your throat during the night.

Conclusion

While caffeine is not the root cause of phlegm, its indirect effects—dehydration that thickens mucus and relaxation of the esophageal sphincter that leads to acid reflux—can significantly contribute to the sensation of excess mucus in the throat. By focusing on hydration, moderating caffeine intake, and adjusting consumption habits, you can effectively manage and reduce these bothersome symptoms. If the issue persists, a healthcare provider can help rule out other potential causes and provide personalized recommendations. By understanding the link between caffeine and throat phlegm, you can make informed choices to protect your throat health and enjoy your favorite beverages without discomfort.

For more information on acid reflux and its effects, consider consulting resources from trusted institutions such as the Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/15024-laryngopharyngeal-reflux-lpr

Frequently Asked Questions

Your throat may feel phlegmy after drinking coffee for two primary reasons: dehydration and acid reflux. Caffeine is a diuretic, which can lead to thicker mucus. It also relaxes the esophageal sphincter, allowing stomach acid to irritate the throat and trigger increased mucus production.

Decaf coffee is much less likely to cause phlegm than regular coffee. While it contains trace amounts of caffeine, the risk of dehydration is minimal. However, its natural acidity can still be a factor for individuals sensitive to acid reflux.

The onset of phlegm symptoms can vary. Issues related to acid reflux may start shortly after drinking coffee, while phlegm from dehydration may develop gradually over time, especially with consistent high intake without sufficient hydration.

To prevent phlegm from caffeine, prioritize hydration by drinking plenty of water, reduce your overall caffeine intake, and consider switching to lower-acid beverages. Avoiding coffee on an empty stomach and managing acid reflux can also help significantly.

For those sensitive to acidity, cold brew coffee is often a better choice, as it is less acidic than hot-brewed coffee. Warm beverages, including warm coffee, can have a soothing effect but may be irritating if consumed too hot.

Yes, drinking plenty of water is one of the most effective strategies. It helps counteract dehydration, thinning mucus and making it easier for your body to clear it from your throat.

While often thought to increase mucus, dairy's impact is debated. For some, adding high-fat creamers or milk can worsen acid reflux, thereby increasing phlegm. Plant-based alternatives may be a better option if you are sensitive.