How to choose a cough medicine

This past week, my husband has sick with a low-grade fever, barking cough, nausea, diarrhea, and a tightness in his chest. After 3 days of this misery, we had him tested for COVID. Thankfully, his result came back negative.

There are 2 types of cough: productive and non-productive. Coughing that produces mucus is called a productive cough while coughing without bringing up any fluid or phlegm is a non-productive cough.

Productive coughs bring up mucus. The mucus may be clear, blood-tinged, or even green-colored. Non-productive coughs range from an annoying tickle in the back of your throat to a cough with stubborn, sticky phlegm that makes you feel like your chest is on fire.

There are several types of cough medicine. Which one should you use?

Guaifenesin, pronounced gweye-FEN-ah-SIN, was discovered in 1949. It was introduced as a prescription cough syrup called Robitussin®, named after the A.H. Robbins company which produced it. By the time I graduated from pharmacy school 30 years later in 1979, Robitussin® was the most prescribed cough medicine in the country. Back then it was available in several formulations, including Robitussin® PE, Robitussin® AC, and Robitussin® DM. Today, Robitussin® continues to be the most widely recognized brand of cough medicine.

Guaifenesin is an expectorant. It works by increasing the fluid in your sinuses, throat, and lungs. This helps liquefy sticky phlegm and mucus so that you can cough it up and out. Expectorants and cough suppressants are both called "cough medicine," but they work differently. Cough suppressants dampen down your cough, helping you get much-needed rest at night but don’t help liquify and remove stubborn, gunky phlegm like an expectorant can.

Guaifenesin can relieve chest congestion and sinus pressure for up to 12 hours without causing drowsiness. Both the prescription medicine Entex® and its extended-release version, Entex LA®, contain guaifenesin. A similar drug called Entex PSE® contains both guaifenesin and pseudoephedrine, the decongestant found in the original formulation of Sudafed®.

Entex® and Entex PSE® were quite successful in treating sinusitis and cold symptoms. When the patent protection on those branded medicines expired, the company applied to the Food and Drug Administration (FDA) to sell them without a prescription. Mucinex® and Mucinex-D® were born.

Adding a decongestant to guaifenesin can help relieve sinus pressure and calm a stubborn, non-productive cough. Mucinex-D® is the non-prescription equivalent of Entex® PSE.

Robitussin® and Robitussin® DM cough syrup both contain guaifenesin, but at lower doses than Mucinex® tablets. Most formulations of Robitussin® DM have 100mg guaifenesin per teaspoonful, compared to 600mg in each Mucinex® tablet and 1200mg in each tablet of Mucinex® Maximum Strength.

The most common side effect of guaifenesin is an upset stomach. I suggest you start with one or two tablets of the 600mg long-acting form of guaifenesin every 12 hours. Taking guaifenesin with a full glass of water also helps it work better. If it bothers your stomach, try taking it with food, or decrease the dose.

The best non-prescription cough medicine contains dextromethorphan. Robitussin® DM includes 10mg of dextromethorphan per teaspoonful. Delsym® and Robitussin 12-Hour Relief are more concentrated, containing three times the amount of active ingredient. Delsym® and Robitussin 12-Hour Relief® work to suppress cough for up to 12 hours, compared with only four to six hours of relief from cough for the standard dextromethorphan formulation.

Here Are 6 Tips For Selecting a Cough Medicine:

1. Keep yourself hydrated.

Drink plenty of fluids. They will help keep your secretions more liquid and less sticky, making it easier to cough them up.

2. Loosen thick mucus.

If you have thick “gunky” phlegm, don’t suppress your cough. Instead, use an expectorant like Mucinex® to help liquefy the phlegm so you can cough it up and out.

3. Suppress your cough at night.

Coughs can disrupt your sleep. Dextromethorphan is an effective non-prescription cough suppressant, available as (Delsym®) or Robitussin® 12 Hour Cough Relief.

4. Use a cough suppressant and an expectorant together.

An expectorant helps liquefy thick sticky mucus so you can cough it up and out, but it doesn't suppress a cough. If coughing interferes with your sleep, add a cough suppressant. You can take BOTH at the same time if needed.

5. Add a decongestant.

Pseudoephedrine reduces post-nasal drip and helps relieve a tickly, non-productive cough. Mucinex-D® contains both pseudoephedrine and guaifenesin.

6. Avoid phenylephrine.

The decongestant phenylephrine is only 1/3 as effective as pseudoephedrine. I recommend you only purchase Sudafed® or Mucinex-D® formulas containing pseudoephedrine, which are available behind the counter at your local pharmacy.


Dr. Louise Achey, Doctor of Pharmacy, is a 40-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Check out her NEW website for daily tips on how to take your medicine safely. ®2021 Louise Achey



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