What does cough suppresant do? A guide to antitussive medications

October 6, 2025 •

4 min read

According to MedlinePlus, cough suppressants are medications called antitussives that work by decreasing activity in the part of the brain that causes coughing. These drugs are primarily used to temporarily relieve dry, irritating coughs that do not produce mucus, and do not treat the underlying cause.

Quick Summary

Cough suppressants, also known as antitussives, inhibit the cough reflex in the brain to provide relief from persistent, nonproductive coughs. These medications are not suitable for wet, productive coughs and include ingredients like dextromethorphan or, in some cases, codeine.

Key Points

Inhibit the Cough Reflex: Cough suppressants, or antitussives, work by blocking the cough reflex in the brain, reducing the urge to cough.
Best for Dry Coughs: They are most effective for treating dry, irritating, nonproductive coughs that don't produce mucus.
Central vs. Peripheral Action: Some suppressants act centrally on the brain's cough center (e.g., dextromethorphan), while others act peripherally on nerve endings in the lungs (e.g., benzonatate).
Different from Expectorants: Unlike suppressants, expectorants (like guaifenesin) work by loosening and thinning mucus to help you cough it up.
Potential for Side Effects: Common side effects include drowsiness and dizziness, and higher doses can lead to more serious issues like hallucinations or seizures.
Consult a Professional: It is important to consult a healthcare provider before using cough suppressants, especially for children or those with underlying health conditions.

Understanding the Cough Reflex

Coughing is a natural and important protective reflex that helps clear irritants, mucus, and foreign material from your airways. It is a complex process controlled by a central nervous system pathway. When irritant receptors in the respiratory tract are stimulated, they send a signal to the "cough center" in the brainstem, which in turn triggers a forceful expulsion of air. A persistent or dry cough, however, can be disruptive and uncomfortable, interfering with sleep and daily activities. It is in these cases that a medication to suppress the reflex, known as an antitussive, can be beneficial.

The Mechanism of Action: How Cough Suppressants Silence the Cough

Antitussive medications work by interrupting the cough reflex arc at different points. They can be broadly classified as either centrally acting or peripherally acting, depending on where they exert their primary effect.

Centrally Acting Agents

Centrally acting cough suppressants, such as dextromethorphan, work directly on the cough center in the medulla of the brain. They elevate the threshold for coughing, making the body less sensitive to the signals that trigger the reflex. Dextromethorphan, for example, is a non-opioid that is structurally similar to codeine but does not have the same addictive properties at therapeutic doses. It is a common active ingredient in many over-the-counter (OTC) cold and cough products. Prescription antitussives, such as codeine and hydrocodone, are also centrally acting opioid derivatives that depress the cough reflex. However, their use is more limited due to potential side effects like addiction, sedation, and respiratory depression.

Peripherally Acting Agents

Peripherally acting cough suppressants affect the nerve endings in the respiratory tract, rather than the brain. A common example is benzonatate, which is a prescription medication. It acts as a local anesthetic, numbing the stretch receptors in the lungs, pleura, and bronchi. By desensitizing these receptors, benzonatate reduces the signals sent to the brain's cough center, thereby suppressing the cough.

Types of Cough Suppressants

Over-the-Counter (OTC) Antitussives: These are readily available at pharmacies and include ingredients like dextromethorphan (often labeled as "DM" on product packages) and the antihistamine diphenhydramine. Diphenhydramine can suppress coughs but also causes drowsiness, making it useful for nighttime relief.
Prescription Antitussives: For more severe or chronic coughs, a healthcare provider may prescribe medications like benzonatate or opioid-based suppressants such as codeine or hydrocodone.
Combination Medications: Many products combine a cough suppressant with other ingredients like expectorants (e.g., guaifenesin), decongestants, or pain relievers to address multiple symptoms simultaneously.

Cough Suppressant vs. Expectorant

It is crucial to differentiate between cough suppressants and expectorants, as they treat different types of coughs. Using the wrong medication can be ineffective or even counterproductive. A cough suppressant should be used for a dry, nonproductive cough, whereas an expectorant is used for a wet, productive cough to help clear mucus.


Feature	Cough Suppressant (e.g., Dextromethorphan)	Expectorant (e.g., Guaifenesin)
Primary Function	Blocks the cough reflex in the brain.	Thins and loosens mucus in the airways.
Best For	Dry, irritating, nonproductive coughs.	Wet, productive coughs with chest congestion.
Example Ingredients	Dextromethorphan (DM), Codeine, Benzonatate.	Guaifenesin.
Mechanism	Acts centrally on the brain's cough center or peripherally on nerve endings.	Increases the volume and reduces the viscosity of respiratory secretions.
Goal	To reduce the frequency and intensity of coughing.	To make coughing more effective at clearing mucus.

Potential Side Effects and Overdose Risk

While generally safe at recommended doses, cough suppressants can cause side effects. Common ones for OTC suppressants include dizziness, drowsiness, nervousness, and gastrointestinal upset. Prescription opioids like codeine carry additional risks, including addiction, sedation, and respiratory depression. Overdosing on dextromethorphan can lead to severe adverse effects, including hallucinations, seizures, and respiratory issues. For benzonatate, chewing or sucking the capsules can lead to a dangerous numbing of the mouth and throat, causing choking or spasms. Always follow dosage instructions carefully and consult a healthcare provider with any concerns.

When to Use and When to Avoid Cough Suppressants

A cough suppressant is most appropriate for a nonproductive, hacking cough that disrupts sleep or causes discomfort. For coughs with phlegm, suppressing the cough reflex can prevent the clearance of mucus, potentially prolonging the illness. It is crucial to match the medication to the type of cough. Certain populations, such as children under a certain age (often 6 years or younger, depending on the product) and individuals with conditions like asthma or COPD, should avoid some cough suppressants due to safety concerns or the risk of worsening symptoms. Always consult a healthcare professional before taking any new medication, especially if you have an underlying medical condition.

Conclusion

Cough suppressants effectively reduce the urge to cough by acting on the central nervous system or local nerve receptors. They are best suited for dry, nonproductive coughs that interfere with rest and daily life. However, they are not a one-size-fits-all solution and should be chosen based on the type of cough and a person's individual health status. Understanding the difference between suppressants and expectorants is vital for effective relief. While OTC options are available, prescription-strength medications exist for more severe cases. It is always wise to consult a healthcare provider or pharmacist for guidance to ensure safe and effective use.

For more detailed pharmacological information on cough suppressants like dextromethorphan, you can visit the National Institutes of Health's MedlinePlus resource.

Frequently Asked Questions

A cough suppressant, or antitussive, works by blocking the cough reflex, typically by acting on the cough center in the brain, to temporarily provide relief from a dry, nonproductive cough.

You should use a cough suppressant for a dry, hacking cough. If you have a wet, productive cough with a lot of mucus, an expectorant like guaifenesin is a better choice because it helps thin and loosen the mucus so you can cough it up.

Yes, dextromethorphan (often labeled as 'DM') is the most common active ingredient in over-the-counter cough suppressants. It works by decreasing activity in the brain's cough center.

Common side effects can include dizziness, drowsiness, nervousness, nausea, and stomach pain. More serious side effects can occur with high doses, including hallucinations and confusion.

You should consult a healthcare provider before giving any cough medicine to a child. The FDA recommends against using OTC cough and cold products for children younger than 2, and some guidelines advise against use for children under 6 or even 12.

The duration of a cough suppressant's effect varies depending on the specific product. For example, some dextromethorphan products last 4-8 hours, while extended-release formulas can last up to 12 hours.

Yes, some multi-symptom cold and flu products combine a cough suppressant and an expectorant. These are designed to address both the urge to cough and the presence of mucus.

Yes, prescription cough suppressants include opioid-based medications like codeine and hydrocodone for severe coughs, and non-opioid options like benzonatate, which acts as a local anesthetic in the lungs.