What causes bad breath and a bitter taste in the mouth?

Generally, bad breath and a bitter taste in the mouth upon waking may be caused by factors such as reduced saliva secretion during sleep, improper diet, gingivitis, gastroesophageal reflux disease (GERD), cholecystitis, and others. If discomfort occurs, timely medical consultation is recommended. Detailed explanations are as follows:

1. Reduced saliva secretion upon waking

During sleep at night, salivary glands produce significantly less saliva, reducing the mouth's self-cleansing ability. Bacteria multiply in the mouth, breaking down food residues and producing unpleasant odors. The reduced saliva can also cause dryness and bitterness in the mouth. After waking, promptly rinse the mouth with warm water, brush teeth, and clean bacteria and food residues in the mouth. Avoid eating overly salty or dry foods before bedtime, and drink a small amount of warm water to keep the mouth moist. Develop daily habits such as brushing teeth morning and night, rinsing after meals, and regularly cleaning the tongue coating.

2. Improper diet

Consuming excessive spicy, greasy, or irritating foods the previous night, or heavy drinking and smoking, may leave residual odorous substances in the mouth and gastrointestinal tract, leading to bad breath and a bitter taste in the mouth the next morning. Adjust dietary habits by choosing light, easily digestible foods for dinner, such as vegetables and porridge. Reduce intake of spicy and fried foods, and avoid drinking and smoking before bedtime. If the previous night's diet was improper, drink more warm water the next day to promote gastrointestinal metabolism.

3. Gingivitis

Dental plaque and tartar buildup can irritate the gums, causing inflammation, redness, and bleeding. Bacterial proliferation produces unpleasant odors, and inflammatory secretions may cause a bitter taste in the mouth. Maintain the habit of brushing teeth morning and night, use dental floss to clean between teeth, and regularly visit the hospital for professional tartar removal. Rinse the mouth promptly after meals to reduce food residue. If inflammation is evident, use medications such as compound chlorhexidine mouthwash, metronidazole mouthwash, or tinidazole tablets under a doctor's guidance to inhibit bacterial growth and alleviate inflammation.

4. Gastroesophageal Reflux Disease (GERD)

During sleep, patients with GERD may experience reflux of stomach contents into the esophagus and mouth. The stomach acid and contents cause bad breath, while acidic substances irritating the oral mucosa lead to a bitter taste. Long-term reflux may also damage the esophageal mucosa. Avoid eating for three hours before bedtime, elevate the upper body by 15–20 degrees while sleeping, and reduce reflux. Limit intake of high-fat foods, chocolate, coffee, and other foods that can trigger reflux. Medications such as omeprazole enteric-coated capsules, rabeprazole sodium enteric-coated tablets, or domperidone tablets may be used under a doctor's guidance to suppress gastric acid secretion and enhance gastric motility.

5. Cholecystitis

When gallbladder function is abnormal, bile excretion becomes obstructed, possibly leading to bile reflux into the stomach and mouth, causing a bitter taste. Bile stasis may also impair gastrointestinal digestion, causing food retention and bad breath. Adopt a light, low-fat diet and avoid consuming fatty foods such as animal offal and fried foods. Maintain regular meal times and avoid overeating. Medications such as anti-inflammatory and bile-promoting tablets, ursodeoxycholic acid capsules, or cefixime dispersible tablets may be used under medical guidance to improve gallbladder function, control inflammation, and, if necessary, follow medical advice for further treatment.

In daily life, maintain a regular routine and avoid staying up late. Keep good oral hygiene and undergo regular dental checkups.