Indigestion can lead to shoulder pain. While many associate shoulder discomfort with muscle strain or injury, the body’s complex nervous system can cause pain from internal organs to be felt in seemingly unrelated areas, including the shoulder.
The Mechanism Behind Referred Pain
The phenomenon where pain from internal organs is perceived in a distant body part is known as referred pain. This occurs because sensory nerves from internal organs, such as those in the digestive system, converge and share pathways with nerves from the skin and muscles in areas like the shoulder. The brain can misinterpret these signals, attributing the discomfort to a more common, superficial source like the shoulder.
The diaphragm, a dome-shaped muscle separating the chest and abdominal cavities, is a key player in referred pain. It receives sensory innervation from the phrenic nerve, originating from C3, C4, and C5 spinal nerve roots in the neck. These same spinal segments also supply sensory nerves to the shoulder and neck, including the supraclavicular nerves. Therefore, irritation of the diaphragm, often from digestive issues, sends signals along the phrenic nerve to these shared segments. The brain then interprets these signals as shoulder pain, even if the problem is abdominal.
Digestive Conditions That Cause Shoulder Pain
Several digestive conditions can irritate the diaphragm or stimulate nerves, causing referred shoulder pain. One common culprit is gastroesophageal reflux disease (GERD). When stomach acid repeatedly flows back into the esophagus, it can irritate the lower esophagus near the diaphragm, potentially causing pain between the shoulder blades or in the chest. This pain can sometimes be mistaken for cardiac issues.
Gallbladder problems, particularly gallstones, are another frequent cause. The gallbladder, beneath the liver in the upper right abdomen, stores bile for digestion. If gallstones block bile ducts or cause inflammation (cholecystitis), the inflamed organ can irritate the phrenic nerve. This often causes pain in the upper right abdomen, but it can also radiate to the right shoulder blade or between the shoulder blades, especially after fatty meals.
Pancreatitis, inflammation of the pancreas, can also cause referred shoulder pain. The pancreas is behind the stomach in the upper abdomen. When inflamed, often due to gallstones or excessive alcohol, pain typically begins in the upper abdomen and can spread to the back or under the left shoulder blade. Trapped gas and bloating can also exert pressure on the diaphragm, leading to a dull ache or discomfort in the shoulder.
Distinguishing Pain Origin
Differentiating shoulder pain caused by indigestion from musculoskeletal issues is important for proper management. Pain originating from musculoskeletal problems, such as muscle strains, sprains, or rotator cuff injuries, typically worsens with movement of the arm or shoulder, or with direct pressure on the affected area. There may also be tenderness to touch, swelling, or a limited range of motion in the shoulder joint.
In contrast, referred shoulder pain from indigestion often presents differently. This type of pain may feel constant, dull, aching, or even sharp, but it usually does not change with shoulder movement or positioning. Accompanying symptoms can offer clues, such as heartburn, a burning sensation in the chest, bloating, nausea, or pain that appears after eating. Relief with antacids or changes in diet might also suggest a digestive origin.
When to Consult a Doctor
While indigestion-related shoulder pain is often benign, certain symptoms warrant immediate medical attention. Seek prompt care if shoulder pain is severe, sudden in onset, or accompanied by symptoms such as chest pain, shortness of breath, dizziness, sweating, or pain radiating to the arm or jaw. These could be signs of a heart attack or other serious conditions that require urgent evaluation.
Consult a healthcare provider if shoulder pain linked to indigestion is persistent, worsening, or does not improve with over-the-counter remedies. Other red flags include unexplained weight loss, difficulty swallowing, black or bloody stools, persistent vomiting, or jaundice. Professional medical advice is crucial for accurate diagnosis and appropriate treatment.