The question of whether hitting someone on the back helps with a cough is a common source of confusion, largely because a forceful back slap is a recognized technique for a different, and more acute, respiratory problem. While back blows are a life-saving measure for a person who is choking, applying them to someone with a typical cough is generally ineffective and can be harmful. A standard cough is the body’s natural defense mechanism, and interrupting it with physical force often works against the body’s protective efforts. Understanding the physiology of a cough and the specific purpose of back percussion clarifies why these two actions should not be confused.
The Purpose of a Cough
A cough is a complex reflex action designed to protect the lower respiratory tract. The reflex begins when irritant receptors in the pharynx, larynx, trachea, and bronchi are stimulated by foreign particles, excessive mucus, or inflammation. This stimulation sends a signal along the vagus nerve to the cough center in the brainstem, which then triggers a rapid response.
The reflex initiates a deep inspiration, followed by the closure of the vocal cords and a forceful contraction of the chest and abdominal muscles. This sudden muscle tension generates immense pressure within the lungs, which is explosively released when the vocal cords open. The resulting high-velocity airflow is designed to clear the airway of the offending material.
Coughs are broadly categorized as either productive or non-productive. A productive, or wet, cough brings up phlegm or mucus from the lungs and should not be suppressed, as it actively removes pathogens or debris. In contrast, a non-productive, or dry, cough is often triggered by inflammation or irritation and does not bring up mucus.
Back Percussion: Mechanism and Intended Use
Back percussion, often referred to as a “back blow,” has a specific, medically sanctioned application: treating a Foreign Body Airway Obstruction (FBAO), or choking. This technique is designed to create a sudden, sharp jolt of pressure to dislodge an object that has completely or severely blocked the windpipe. The forceful blow, delivered with the heel of the hand between the shoulder blades, is intended to generate an artificial cough.
The shockwave from the back blow rapidly compresses the air in the lungs, increasing the pressure behind the trapped object. This spike in intrathoracic pressure forces the object upward and out of the airway. Standard first aid protocols recommend alternating up to five forceful back blows with five abdominal thrusts (the Heimlich maneuver) until the object is expelled or the person loses consciousness.
Chest Physiotherapy
Another form of back percussion is used in Chest Physiotherapy (CPT). This technique involves a respiratory therapist or trained caregiver rhythmically clapping the patient’s back and chest with a cupped hand. The goal of this specialized percussion is to loosen thick, sticky mucus deep within the lungs, often associated with conditions like cystic fibrosis or chronic obstructive pulmonary disease (COPD). This rhythmic clapping helps move the mucus into larger airways so the patient can then cough it up effectively.
Why Hitting Someone Who is Coughing Is Not Recommended
Applying a forceful back blow to a person experiencing a standard cough is not recommended because it misinterprets the patient’s condition and the body’s natural response. A person who is coughing maintains a partial airway obstruction, meaning air is still able to move past the foreign object or mucus. If air is moving, the body’s natural, forceful cough is the most effective and safest way to clear the irritant.
Intervening with a back blow can be detrimental, potentially turning a partial obstruction into a complete one. The sudden, external force might cause the foreign material to be inhaled deeper into the airway rather than expelled, effectively worsening the situation. Medical guidelines for choking emphasize that if the person is capable of speaking or coughing forcefully, a rescuer should only encourage them to continue coughing.
A forceful, non-medical back slap carries risks of physical injury. The aggressive nature of an improperly applied blow can cause soft tissue damage or, in rare instances, lead to a fractured rib or spinal injury, especially in older or frail individuals. Furthermore, a slap to the back has no anatomical mechanism to directly address the source of irritation for most common coughs.
Effective Relief Strategies for Persistent Coughs
For coughs unrelated to acute choking, several medically recognized strategies focus on treating the underlying cause and managing symptoms.
Home and Over-the-Counter Treatments
- Hydration: Drinking plenty of fluids helps thin the mucus, making it less viscous and easier for the body to expel. Warm liquids, such as herbal teas or broth, can also soothe an irritated throat.
- Moisture: Using a cool-mist humidifier or breathing steam introduces moisture to the upper airways, which can calm irritation and help loosen respiratory secretions.
- Expectorants: Medications like guaifenesin thin mucus to make productive coughs more efficient.
- Suppressants: Medications such as dextromethorphan block the cough reflex and are best reserved for dry, non-productive coughs that interfere with rest.
If a cough persists for more than eight weeks, it is classified as chronic and warrants professional medical attention. Concerning symptoms that require immediate medical evaluation include coughing up blood, high fever, or shortness of breath.