Experiencing an itchy back while coughing can be puzzling. This sensation often stems from how body systems interact during a cough. Understanding these physiological mechanisms can clarify why a cough might trigger an itch in the back.
The Cough Reflex
A cough is a complex and forceful expulsion of air, serving as a protective reflex to clear irritants from the airways. This action involves a coordinated effort from various muscles and pressure changes within the body.
When a cough is initiated, the diaphragm, a dome-shaped muscle separating the chest and abdomen, contracts. Simultaneously, the intercostal muscles located between the ribs and the abdominal muscles also engage.
These muscular contractions lead to a rapid increase in pressure within the chest and abdominal cavities. The glottis, a part of the voice box, briefly closes before opening suddenly, allowing air to be expelled at speeds estimated around 100 miles per hour.
This sudden muscular activity and pressure fluctuations can impact surrounding anatomical structures, including the spine and back tissues. The forces generated can temporarily strain or move these structures, potentially influencing nerve activity.
Nerve Pathways and Sensations
The sensation of itching in the back during a cough is linked to the body’s nerve network, which transmits signals to the brain. Sensory nerves, found throughout the skin and deeper tissues, relay information about touch, pressure, pain, and itch to the central nervous system, including the brain and spinal cord. These signals travel along nerve fibers to the spinal cord and then ascend to the brain for interpretation.
Areas of skin are supplied by specific spinal nerves in segments known as dermatomes. Each dermatome connects to a single spinal nerve that relays sensory information from that skin region to the brain. While some overlap exists between adjacent dermatomes, irritation or compression of a spinal nerve during a cough can result in a perceived sensation, such as itching, in its corresponding dermatome in the back. This phenomenon, known as referred sensation, means a signal from deeper nerve irritation might be felt on the skin surface.
Common Explanations for the Itch
The itchy back sensation during coughing can arise from several physiological responses, primarily involving nerve irritation and muscle activity.
One common reason is transient irritation or compression of spinal nerves or their branches. Sudden, forceful movements of the diaphragm, intercostal, and abdominal muscles during a cough can momentarily shift or strain vertebrae and surrounding soft tissues, potentially impinging on nearby nerves. This brief pressure or stretch on sensory nerves can trigger an itch signal the brain interprets as originating from the back.
Another factor is muscle tension and spasm during a strong cough. Back and abdominal muscles contract to generate coughing force. These contractions can lead to temporary muscle fatigue or spasms, irritating nerves within or near them. This irritation can manifest as an itch on the skin overlying the affected muscles.
The vagus nerve, for instance, transmits signals from the airways to the brain to initiate the cough reflex. If irritation exists within the lungs or airways, these signals, traveling along shared nerve pathways, might be misinterpreted by the brain as an itch in a distant somatic area like the back. This is similar to how pain from a heart attack can be felt in the arm.
Transient vascular changes during a cough might contribute. The sudden increase in intrathoracic and intra-abdominal pressure can momentarily affect blood flow in small capillaries and vessels in the back. This temporary alteration in circulation or a transient inflammatory response could lead to histamine release, known to cause itching.
When to Seek Medical Advice
While an itchy back when coughing is often a temporary and harmless occurrence, certain accompanying symptoms warrant medical evaluation. It is advisable to consult a healthcare professional if the itching is persistent, severe, or not directly linked to coughing.
Other symptoms warranting medical attention include pain that is severe, worsening, or not relieved by rest, especially in the upper back. Numbness, tingling, or weakness in the arms or legs, particularly if radiating down the limbs, could indicate nerve involvement and needs assessment.
Unexplained fever, sudden weight loss, or changes in bowel or bladder control accompanying back discomfort or itching are serious signs needing immediate medical attention. If the cough itself is severe, prolonged, or accompanied by other concerning symptoms like chest pain or difficulty breathing, a doctor should be consulted to rule out more serious underlying conditions.