The most widely used over-the-counter cough suppressant is dextromethorphan (often labeled “DM” on the box), found in brands like Robitussin DM, Delsym, and many store-brand equivalents. It works by dulling the cough reflex in the brain, and for most adults with a dry, nagging cough from a cold or upper respiratory infection, it’s the go-to starting point. But it’s not the only option, and whether it’s the right choice depends on the type of cough you have, your age, and what other medications you take.
Over-the-Counter Cough Suppressants
Dextromethorphan is the active ingredient in nearly every OTC product marketed specifically to suppress coughing. It’s available as syrups, capsules, lozenges, and extended-release suspensions. Standard doses last about four to six hours, while extended-release formulas can work for up to 12 hours. It’s most effective for dry, nonproductive coughs, the kind that keeps you awake at night but doesn’t bring up mucus.
If your cough is wet and producing phlegm, a suppressant isn’t always ideal. In that case, an expectorant like guaifenesin (found in Mucinex) helps thin mucus so you can clear it more easily. Many combination products contain both dextromethorphan and guaifenesin, but it’s worth reading the label carefully. Combination cold medicines often bundle in pain relievers or decongestants you may not need, and doubling up on acetaminophen or other ingredients by taking multiple products is a common and preventable mistake.
Prescription Cough Medicines
When OTC options aren’t enough, doctors have a few prescription tools. Benzonatate (sold as Tessalon Perles) is one of the most commonly prescribed. Unlike dextromethorphan, which acts on the brain, benzonatate works by reducing the cough reflex directly in the lungs and airways. One important safety rule: the capsules must be swallowed whole. If you crush, chew, or suck on them, the medication can numb your mouth and throat, creating a choking risk.
For severe coughs, doctors sometimes prescribe codeine-based cough syrups. These are opioid medications, so they come with stricter rules. The FDA label for codeine cough products specifies they should be used at the lowest effective dose for the shortest possible time. If the cough doesn’t improve within five days, the prescribing guidance says to stop and investigate other causes rather than increasing the dose. Codeine cough syrups are not safe for children under 6 because of the risk of fatal respiratory depression, and they’re also not appropriate for treating asthma-related coughs.
Honey as a Cough Remedy
For a non-medication option, honey has genuine clinical support. A study published in The Journal of Pediatrics tested buckwheat honey against dextromethorphan and no treatment in 105 children with upper respiratory infections. A single bedtime dose of honey reduced cough severity by 47.3%, compared to 24.7% with no treatment. Dextromethorphan, notably, performed no better than no treatment in that trial. When honey and dextromethorphan were compared directly, there was no significant difference between the two.
This makes honey a particularly useful option for children between ages 1 and 4, an age group where OTC cough medicines are not recommended (more on that below). A spoonful of honey before bed can meaningfully reduce nighttime coughing. Just never give honey to infants under 12 months because of the risk of botulism.
Cough Medicine Safety for Children
The FDA does not recommend OTC cough and cold medicines for children younger than 2 because of the risk of serious, potentially life-threatening side effects. Manufacturers have voluntarily gone further, labeling most of these products with “do not use in children under 4 years of age.” This applies to homeopathic cough products too. The FDA has flagged cases where children under 4 who took homeopathic cough remedies experienced seizures, allergic reactions, difficulty breathing, and dangerous drops in blood potassium and blood sugar.
Even for children old enough to take these products, the biggest risks come from getting more than the recommended dose, taking doses too frequently, or unknowingly doubling up by using two products that contain the same active ingredient. If you’re giving a child cough medicine, use only a single product, measure with the included dosing device (not a kitchen spoon), and check the active ingredients against anything else the child is taking.
A Dangerous Interaction to Know About
Dextromethorphan has a significant interaction with certain antidepressants that many people aren’t aware of. If you take an SSRI like fluoxetine (Prozac) or bupropion (Wellbutrin), using a DM cough product can raise the risk of serotonin syndrome, a potentially dangerous condition caused by too much serotonin activity in the brain. Symptoms include agitation, confusion, rapid heart rate, muscle twitching, and in severe cases, seizures.
The reason is that dextromethorphan itself acts on serotonin pathways, and both fluoxetine and bupropion block the liver enzyme that normally breaks dextromethorphan down quickly. The result is higher drug levels lasting longer, compounding the serotonin effect. This interaction is well-documented in clinical case reports. If you take any antidepressant, check with your pharmacist before reaching for a DM cough product. Benzonatate, by comparison, does not carry this same risk.
Wet Cough vs. Dry Cough
Choosing the right medicine starts with identifying what kind of cough you have. A dry cough produces no mucus and often feels like a tickle or irritation in the throat. This is the type that cough suppressants like dextromethorphan and benzonatate are designed to treat. A wet or productive cough brings up phlegm, and suppressing it can actually be counterproductive because your body is trying to clear mucus from your airways. For a wet cough, an expectorant or simply staying well-hydrated is often more helpful than a suppressant.
Postnasal drip, a common cause of coughing from colds and allergies, can create both types. If mucus dripping down the back of your throat is triggering your cough, an antihistamine or decongestant may address the root cause more effectively than a cough suppressant alone.
When a Cough Needs Medical Attention
Most coughs from colds and upper respiratory infections clear up within a couple of weeks. In adults, a cough lasting longer than eight weeks is classified as chronic and warrants evaluation. For children under 15, that threshold is four weeks. Red flags that suggest something more serious include coughing up blood, unexplained weight loss, hoarseness, fever that won’t resolve, excessive mucus production, shortness of breath, or recurrent pneumonia. A persistent cough can be driven by conditions like asthma, acid reflux, or medication side effects (ACE inhibitors, a common blood pressure drug class, cause a chronic dry cough in roughly 1 in 10 users), and treating the underlying cause is the only way to stop it.