Cough drops are over-the-counter lozenges designed to relieve the irritation and discomfort associated with a cough or sore throat. They function primarily by interacting with the mucous membranes in the mouth and pharynx, providing localized relief. The mechanism of action involves both physical soothing and the delivery of active medicinal ingredients.
Defining Demulcents and Local Anesthetics
The initial, non-medicinal effect of a cough drop comes from its demulcent properties, which provide immediate physical relief to the irritated throat tissue. A demulcent is a substance that relieves irritation of mucous membranes by forming a protective film over the surface. Common demulcent ingredients include pectin, glycerin, honey, or syrup.
The act of slowly dissolving the lozenge stimulates saliva production in the mouth. This increase in moisture helps to lubricate the throat, and the demulcent ingredients mix with the saliva to create a soothing, viscous coating. This protective barrier shields the irritated tissues from further damage. For drops with more immediate pain relief, a secondary function involves local anesthetics, which numb the throat to reduce discomfort.
Key Active Ingredients and Their Actions
The therapeutic effect of a cough drop depends heavily on its active ingredients, which can be grouped into three main categories. The first group is oral anesthetics or analgesics, which work to temporarily block pain signals. Ingredients like benzocaine or phenol function as local anesthetics by blocking the transmission of pain impulses along nerve fibers in the throat.
Some medicated lozenges contain cough suppressants, also known as antitussives, to target the cough reflex centrally. Dextromethorphan (DXM) is the most widely used ingredient in this category. This compound acts on the cough center in the brain to reduce the activity that triggers the involuntary cough reflex.
The third category includes counterirritants, such as menthol and eucalyptus oil. Menthol creates a cooling sensation by activating receptors, which distracts from the pain and irritation. Menthol also possesses mild local anesthetic properties and can act as a mild decongestant by improving the subjective sensation of airflow. Eucalyptus oil often works synergistically with menthol and may help reduce inflammation and clear nasal congestion.
Proper Use and Safety Considerations
For cough drops to work effectively and safely, it is important to follow the dosing instructions provided on the package, which typically recommend taking them every two to four hours. Allowing the lozenge to dissolve slowly in the mouth is essential to prolong the contact time of the active ingredients and the demulcent coating. Hard lozenges pose a choking hazard and should be administered with caution, especially to young children.
When using drops containing the active cough suppressant dextromethorphan, consumers must be vigilant about not exceeding the recommended dose within a 24-hour period. Combining products containing DXM can lead to accidental overdose and serious side effects. A cough that persists for more than seven days, returns, or is accompanied by a high fever, rash, or persistent headache requires professional medical attention.