Cough is a common symptom for which many patients seek advice at urgent care clinics and emergency departments, especially when they experience episodes during peak allergy season due to postnasal drip and congestion.
Cough is a common symptom for which many patients seek advice at urgent care clinics and emergency departments, especially when they experience episodes during peak allergy season due to postnasal drip and congestion. Some of these patients initially elect to self-treat with an OTC cough product.1
The pharmacy shelves are lined with cough suppressants, expectorants, and combination products in many forms. The array may be overwhelming for some patients, especially those with preexisting medical conditions or who are taking other medications. Pharmacists are in a key position to evaluate patients with cough; aid them in selecting an OTC product for selftreatment, when appropriate; and encourage them to seek medical care, when warranted, especially if the origin of cough is unknown, the cough is lingering, or the patient exhibits signs of respiratory tract infection.
Because of their extensive drug knowledge, pharmacists can identify patients who may have a cough due to the use of certain medications or medical conditions, and advise them accordingly, or detect who may be abusing cough syrup, a trend known as “robotripping.” According to the National Institute of Drug Abuse, dextromethorphan is one of the 2 most commonly abused cough medications, especially among teens, because large quantities may produce euphoria and hallucinations.2 However, abuse of dextromethorphan can impair motor function; cause numbness, nausea, vomiting, tachycardia, and hypertension; increase body temperature; and result in buildup of excess acid in the body.2 Efforts by many health care providers (HCPs) to increase awareness of dextromethorphan abuse through mitigation campaigns seem to have helped decrease the rate of abuse by more than 40% since 2010.3,4
TYPES AND CAUSES OF COUGH
A cough can be classified as acute or chronic and can be due to irritants, allergens, certain medical conditions, or the use of particular medications (Table 11,5-9).1,5-7 Acute coughs last fewer than 3 weeks, subacute coughs last 3 to 8 weeks, and chronic coughs last longer than 8 weeks.1,5,6 Coughs can be further classified as productive or nonproductive.
Although most coughs are self-limiting, chronic coughs can be annoying and negatively impact quality of life by interfering with sleep and causing musculoskeletal pain/discomfort, hoarseness, headaches, urinary incontinence, chest pain, and exhaustion and fatigue.1,5,7-9 Patients with a chronic cough should be assessed to ascertain its cause and rule out potentially serious medical conditions.
The principal goals of self-treating a cough are to eradicate it and avoid complications. Because treatment is symptomatic, the underlying cause must be identified and treated, as well.1,5,6 For self-treating cough, the plethora of OTC products includes oral antitussives, expectorants, and topical antitussives, all of which are available in several dosage forms, including single-entity or combination products that contain a protussive and an antitussive (Online Table 2).1,6
Table 2. Examples of OTC Cough Products
Alternative/Natural Cough Formulations
Guaifenesin, the only FDA-approved expectorant also recognized as a protussive, is indicated for the symptomatic relief of an acute ineffective, productive cough.1 Although the pharmacokinetics are not completely understood, it appears to be well absorbed after oral administration, with an estimated half-life of approximately 1 hour.1 The use of guaifenesin is not linked with any known drug—drug interactions and is normally well tolerated; however, infrequent adverse effects (AEs) (eg, dizziness, headache, rash, nausea, vomiting, gastrointestinal upset) have been reported.1 Expectorants are available in several dosage forms, including liquids, syrups, granules, tablets, and liquidfilled capsules. Guaifenesin should not be used to treat chronic cough associated with chronic lower respiratory tract diseases such as asthma, chronic obstructive pulmonary disease (COPD), emphysema, or smoker’s cough.1,6
Available FDA-approved OTC oral antitussives include codeine, dextromethorphan, and diphenhydramine in various dosage forms to suit the needs of many patients.1
Most OTC cough suppressants contain dextromethorphan, which is indicated for suppressing a nonproductive cough caused by chemical or mechanical respiratory tract irritation.1,6 Available forms include syrups, liquids, suspensions, liquid-filled gelcaps, granules, and lozenges. Dextromethorphan is well absorbed after oral administration, with a 15- to 30-minute onset of action and a duration of effect of 3 to 6 hours.1 Although uncommon, associated AEs include nausea, drowsiness, vomiting, stomach discomfort, and constipation.1,6
Diphenhydramine is classified as a nonselective first-generation antihistamine with significant sedating and anticholinergic properties.1 Although approved by the FDA as an antitussive, diphenhydramine is not considered a first-line antitussive; it is found in many cold and allergy products, along with other ingredients.1 Diphenhydramine is indicated for suppressing a nonproductive cough caused by chemical or mechanical respiratory tract irritation and acts centrally in the medulla to increase the patient’s cough threshold.1,6 The most common AEs include drowsiness, respiratory depression, blurry vision, urinary retention, and dry mouth.1,6
At antitussive dosages, codeine is classified as a Schedule C-V narcotic and is available without a prescription in many states.1 Codeine is indicated for suppressing a nonproductive cough caused by chemical or mechanical respiratory tract irritation and acts centrally on the medulla to increase the cough threshold. When administered at antitussive doses, codeine has low toxicity and little risk of addiction.1 The most common AEs at antitussive dosages include nausea, vomiting, sedation, dizziness, and constipation. Codeine should be used with caution in individuals with asthma, COPD, respiratory depression, and drug addiction.1,6
The only 2 FDA-approved topical antitussives are camphor and menthol, which are found in ointments and inhalants1; menthol is also found in many types of throat lozenges.1,6 Patients should be counseled about the proper use of these agents and advised to only use them as directed by the manufacturer.
Before recommending any OTC cough product, pharmacists should ascertain whether self-treatment is appropriate and screen patients for any allergy history, medical history, and current medication profile to check for potential drug—drug interactions or contraindications. Pregnant and lactating women and individuals with chronic medical conditions should consult their primary HCP before using OTC cough medications.
During counseling, pharmacists also can remind patients with hypertension about products marketed specifically for their condition and point out to all that they should be reading labels before taking OTC products and checking the ingredients to avoid therapeutic duplications and excessive dosing, especially if using multiple products.
It is imperative for patients to adhere to the recommended dosages and administration guidelines. To ensure proper dosage and accuracy, it is especially critical for parents/caregivers to be reminded to always use calibrated measuring devices when administering liquids and to follow label instructions prior to administering medications to children, especially regarding age limits for use. Parents/caregivers should only give children OTC products manufactured specifically for children and adhere to manufacturers’ recommendations. When in doubt regarding the appropriateness or dose of a medication, parents/caregivers should always consult their pediatrician or pharmacist.
Because cough can be a symptom of many acute and chronic medical conditions, self-treatment may delay identification and treatment of the underlying cause.1 Individuals with signs of chronic cough should be encouraged to seek a medical evaluation from their primary HCP, especially if the cause is unknown or is not improving or worsening (Table 3).1 In many cases, coughs improve or cease if the underlying cause is treated or prevented.1,5 Patients with a smoker’s cough should be encouraged to consider smoking cessation programs,6 and patients exhibiting signs of a cough that is likely due to the use of a medication, such as an angiotensin-converting enzyme (ACE) inhibitor, should talk to their primary HCP or pharmacist about switching to a drug from a class that is not associated with cough. An estimated 20% of patients taking ACE inhibitors experience episodes of dry cough.6 In addition, the use of systemic and ophthalmic beta-adrenergic blockers may cause cough in patients with conditions such as asthma or COPD.6
Ms. Terrie is a clinical pharmacist and medical writer based in Haymarket, Virginia.