Flank pain is discomfort located on the side of the body between the lower ribs and the hips. When coughing causes this pain to spike, it is often due to the dramatic increase in intra-abdominal and intra-thoracic pressure accompanying the forceful expulsion of air. This sudden pressure stresses the muscles, tissues, and organs in the flank region, often revealing an underlying problem. The source of the pain involves diverse structures in this area, including muscles, ribs, kidneys, and lung linings.
Musculoskeletal Sources of Flank Pain
The most frequent cause of flank pain aggravated by coughing involves the muscles and skeleton of the torso. A cough requires the sudden, powerful contraction of numerous core muscles, including the abdominal wall and the intercostals located between the ribs. This forceful action can easily strain or tear these muscle fibers. This leads to a sharp, localized pain instantly reproduced or worsened by coughing, sneezing, or deep breathing.
Intercostal muscle strain is common, causing sharp pain felt along the ribs, often worsened by twisting or bending. Prolonged, violent coughing can occasionally lead to stress fractures or bruising of the lower 11th or 12th ribs. Applying direct pressure (palpation) on the affected muscle or rib often reproduces this superficial pain, distinguishing it from deeper organ pain.
Pain originating from the spine can manifest in the flank area through nerve irritation, known as referred pain. Conditions like a herniated disk or a pinched nerve in the thoracic or lumbar spine cause pain that radiates outward. When the body is jarred by a cough, the movement can briefly compress an already irritated nerve root, intensifying the flank pain. This pain often presents as a deep ache and may be accompanied by numbness or tingling.
Kidney and Urinary Tract Conditions
The kidneys are situated in the upper flank, just below the rib cage, making them a primary source of discomfort. Pain from kidney conditions is described as deep, internal, and non-muscular, often presenting as a dull ache or severe, crampy (colicky) pain. Although the pain is constant, the sudden pressure change from a cough can briefly intensify it by irritating the surrounding tissues.
Kidney stones cause flank pain when they obstruct urine flow, leading to pressure buildup in the renal pelvis or ureter. This pain is sudden, severe, and may radiate toward the groin as the stone moves. Pyelonephritis, a kidney infection, also causes flank pain, but it is usually a persistent, dull ache rather than the intense, colicky pain of a stone.
These kidney-related causes are often accompanied by specific urinary symptoms that distinguish them from musculoskeletal issues. Signs include blood in the urine, a burning sensation during urination, or an increased urge to urinate. A kidney infection may also present with systemic symptoms like fever, chills, nausea, or vomiting.
Respiratory and Pleural Causes
Flank pain worsened by coughing can originate from the respiratory system, specifically the pleura, which is the lining of the lungs and chest cavity. The pleura consists of two thin layers separated by lubricating fluid, allowing them to glide smoothly during breathing.
Pleurisy (pleuritis) involves inflammation of these pleural linings, causing them to rub together during respiration. This friction results in a sharp, stabbing pleuritic pain, which is worsened by deep breaths, sneezing, or coughing. Although the pain is primarily felt in the chest, it can be referred to the lower rib area and upper flank.
Conditions like pneumonia or bronchitis often precede pleurisy, as the infection can spread to the pleural space. In these cases, the pain is directly tied to the movement of the lungs and chest wall during the cough cycle. If fluid accumulates between the pleural layers (pleural effusion), the pain may lessen, but coughing and shortness of breath may persist due to lung compression.
Understanding Warning Signs and Next Steps
While many causes of flank pain when coughing are related to benign muscle strains, certain accompanying symptoms suggest a more serious underlying issue requiring prompt attention. Seek medical evaluation if the flank pain is accompanied by a high fever, severe chills, or uncontrolled nausea and vomiting. These symptoms can point toward a significant infection like pyelonephritis.
Other concerning signs include blood in the urine, an inability to urinate, or pain that radiates intensely into the groin, indicating kidney stones or urinary tract obstructions. If the pain is associated with shortness of breath or persistent chest discomfort, it may suggest a serious respiratory or cardiac concern.
For pain suspected to be a simple muscle strain, resting the area, applying local heat, and taking over-the-counter anti-inflammatory medication can provide relief. A medical professional can accurately diagnose the source of the pain and recommend treatment.