For most dry coughs, an over-the-counter cough suppressant containing dextromethorphan is the most evidence-backed option, though honey works surprisingly well and carries fewer side effects. What you should actually take depends on how long your cough has lasted and what’s causing it, because a dry cough that lingers beyond three weeks often signals something treatable that no cough syrup will fix on its own.
Dextromethorphan: The Best-Studied OTC Option
Dextromethorphan (often labeled “DM” on cough products) is the only over-the-counter cough suppressant that has been shown to reduce cough frequency using objective cough-counting monitors, which regulatory agencies consider the gold standard for measuring whether a treatment actually works. In studies involving over 450 patients, a 30 mg dose produced a statistically significant reduction in cough counts compared to placebo.
That said, the effect is modest. The estimated benefit over doing nothing is around 17%, and it takes roughly two hours to reach peak effectiveness. The upside is that it stays active for a long time, still outperforming placebo after 24 hours. You’ll find it in products like Robitussin DM, Delsym, and many store-brand cough syrups. Look for “cough suppressant” on the label rather than “expectorant,” which is a different ingredient meant for wet, productive coughs.
Why Honey Deserves Serious Consideration
Honey performs as well as dextromethorphan in head-to-head comparisons and significantly better than no treatment at all. A study of 105 children with upper respiratory infections found that a single dose of buckwheat honey before bedtime reduced cough severity by 47% and improved an overall symptom score by nearly 54%, compared with about 25% and 33% for untreated children. Dextromethorphan, meanwhile, showed no significant advantage over doing nothing in that same trial, while honey did.
A spoonful of dark honey (buckwheat is the most studied variety) taken 30 minutes before bed coats the throat and seems to calm the cough reflex through the night. It’s a particularly good choice when you want to avoid medication or when treating children over age one. Never give honey to infants under 12 months due to the risk of botulism.
Lozenges and Throat-Coating Remedies
Dry coughs are often driven by an irritated, scratchy throat, and anything that forms a protective film over that irritated tissue can quiet the cough reflex. Demulcent lozenges containing pectin or glycerin work this way. They don’t suppress cough through your nervous system the way dextromethorphan does. Instead, they physically shield raw throat tissue from the air and swallowing motions that trigger coughing. Brands like Luden’s fall into this category.
Marshmallow root works on a similar principle. The root contains a high concentration of complex sugars (mucopolysaccharides) that form a gel-like coating over irritated mucous membranes in the mouth and throat. This polysaccharide film supports the natural mucus layer and protects it from further irritation. You can find marshmallow root in syrups and lozenges, and user surveys report good tolerability. Sipping warm liquids throughout the day also helps keep throat tissue moist and less reactive.
What Not to Take for a Dry Cough
Guaifenesin, the active ingredient in Mucinex and many “expectorant” products, is designed to thin mucus and make a productive cough more effective. For a strictly dry cough with no mucus, the evidence is mixed at best. One trial found it reduced self-reported cough frequency, but another found no benefit for cough frequency or severity. Its clearest effect was thinning sputum, which isn’t relevant when your cough is non-productive. If you’re shopping the cough aisle, make sure you’re reaching for a suppressant, not an expectorant.
Cough Medicine and Children
The FDA recommends against giving any over-the-counter cough and cold medicines to children under two, citing the risk of serious and potentially life-threatening side effects. Manufacturers have voluntarily extended that warning, labeling products with “do not use in children under 4 years of age.” For young children, honey (for those over age one) and keeping the air humidified are the safest approaches.
Prescription Options for Stubborn Coughs
If over-the-counter remedies aren’t cutting it, a doctor may prescribe benzonatate, a capsule that numbs the stretch receptors in your lungs to quiet the cough reflex. It’s typically taken three times a day as needed. Common side effects include drowsiness, dizziness, nausea, and a stuffy nose. One important detail: the capsules must be swallowed whole. If you chew or crush them, the medication can numb your mouth and throat, creating a choking hazard. This risk is especially dangerous for children, and the capsules should always be stored in a child-proof container out of reach.
For chronic dry coughs that persist for months despite treatment, doctors sometimes turn to nerve-calming medications. Gabapentin, for instance, is typically started at a low dose at bedtime and gradually increased. If there’s no improvement after several weeks at the full dose, further increases are unlikely to help, and other options are explored.
When the Cough Points to Something Else
A dry cough that won’t go away is often a symptom rather than the main problem. Three conditions account for the majority of chronic dry coughs, and treating the right one can make the cough disappear entirely.
Acid reflux (GERD): Stomach acid irritating the throat and airways is a surprisingly common cough trigger, even in people who don’t have obvious heartburn. Treatment starts with dietary and lifestyle changes along with acid-reducing medication. If the cough doesn’t respond to aggressive reflux management, surgical options exist.
Cough-variant asthma: Some people with asthma cough instead of wheeze. A breathing test can reveal airway sensitivity, and standard asthma treatments (bronchodilators and inhaled steroids) typically resolve the cough.
Blood pressure medications: ACE inhibitors, a widely prescribed class of blood pressure drugs, cause a persistent dry cough in up to 15% of people who take them. If you started coughing after beginning a new medication, the fix is simple: switching to a different type of blood pressure drug usually stops the cough within a few weeks.
Signs Your Cough Needs Medical Attention
Any dry cough lasting longer than three weeks without a clear explanation warrants a visit to your doctor. Seek more urgent evaluation if your cough comes with coughing up blood, difficulty breathing, wheezing, extreme fatigue, fever and chills, or sudden unexplained chest pain.