Do Cough Syrups Work?

They have a mix of ingredients but may not work as well as you might think.

No medicine cabinet is fully stocked without some good old cherry-flavored cough syrup—or at least that’s how it feels during cold and flu season.

But does cough syrup even work? And will it work for the type of cough you have? Spoiler alert: Not really.

Mother with syringe giving medicine to her daughter

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How Does Cough Syrup Work?

Colds and the flu can produce a wet—phlegmy—cough or a dry one that doesn't expel mucus from your lungs. Gastroesophageal reflux disease (GERD), COVID-19, and asthma can also produce coughs. Coughing may be brought on by smoking, chronic obstructive pulmonary disease (COPD), and tuberculosis. Then, there's the barking cough caused by croup.

In theory, this is how different ingredients in over-the-counter cough syrups are supposed to work:

  • Antitussive drugs like dextromethorphan (often listed as DM or DXM) or codeine block the body's cough reflex.
  • Expectorants thin mucus to make it easier to cough.
  • Decongestants reduce the swelling of blood vessels in your nose.
  • Antihistamines prevent allergy symptoms like congestion and sneezing.

Although these ingredients are supposed to work in theory, they don't perform well in practice, some research shows.

Does Cough Syrup Give You Any Relief?

Most studies have found little to no evidence that over-the-counter cold medicines work to suppress or stop coughing. In many cases, they've performed no better than a placebo.

A 2021 literature review that looked at studies in children found dextromethorphan didn't improve the quality of sleep and severity of cough. However, high doses can make you feel "high" and cause hallucinations, psychosis, or seizures. The review also found that antihistamines in cough syrup were only slightly more effective than a placebo, an inactive substance that looks like the medicine being tested.

A 2020 review found that cough syrup sometimes works, but not because of the ingredients. Instead, people who take them associate the taste with relief, and when they begin to feel better as part of their body's natural healing processes, they believe it's because of the cough syrup.

People also experienced the placebo effect, meaning their belief in the products allows them to feel better even if the ingredients are inactive or ineffective.

Which Remedies Work?

Although cough syrup may not be as effective as promised, other treatments are available.

If you have a cough, try these remedies instead:

  • Drink plenty of fluids.
  • Run a humidifier or take a steamy shower to loosen mucus.
  • Try Tylenol, Aleve, or Advil for low fever, aches, and pains associated with a cough-producing condition.
  • Suck on cough drops to help relieve throat irritation.

You could also try honey. Studies show it works better than the antihistamines in cough syrup. Although it won't take away your cough, it can soothe it and make your throat more comfortable. Honey also works well in hot beverages like tea because the warmth is also soothing. But don't give honey to kids younger than 12 months because there may be a risk of botulism.

You could also take cough syrup along with other remedies. Cough syrups can feel soothing, and they have one known benefit: They often make you drowsy and help you get to sleep, which is essential when you are sick. (Cough syrup is not recommended for children under the age of 4, though.)

Just don't take more than instructed because some ingredients, especially dextromethorphan, can have depressant or hallucinogenic effects at high doses and may be habit-forming.

How to Make Homemade Cough Drops

Cough drops can help soothe a sore throat by causing you to produce more saliva to moisten your throat. Some medicated cough drops with anesthetic and antiseptic properties can also offer a modest reduction in discomfort.

You could also make homemade cough drops by combining the following:

  • ¼ cup freshly squeezed orange juice
  • 1 tablespoon freshly squeezed lemon juice
  • 2 tablespoons water
  • 2 tablespoons orange blossom honey
  • ½ teaspoon ground cloves
  • ½ teaspoon ground ginger
  • 1 cup turbinado—raw—sugar
  • Zest from one medium orange

Stir all these ingredients in a small pot and simmer them for 20 minutes. Strain to remove seeds and large pieces of zest and continue to simmer and reduce until the liquid mixture reaches 300° Fahrenheit (149° Celsius). Spoon the warm mixture into candy molds and freeze for five to 10 minutes. Unmold the frozen drops and wrap them individually in wax paper.

A Quick Review

There is very little evidence that cough syrup works for a cough, and many studies show that it works no better than a placebo. However, it might help you sleep, and rest is essential to help you fight off illness.

You are likely better off sticking with basic home remedies such as drinking plenty of fluids, using a humidifier, and sucking on cough drops or hard candy.

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17 Sources uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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