Delsym vs. Robitussin – What is the best remedy for persistent cough?

It is a brand name cough syrup that contains the generic drug Dextromethorphan, which acts as a cough suppressant by affecting the signals in the brain that trigger the cough reflex.

Dextromethorphan (available over the counter in the U.S. since 1958) belongs to a group of drugs called cough suppressants that provide temporary relief from the nagging cough caused by a cold, the common flu, or by inhaled irritants.

However, this drug differs from other cough suppressants in that it has a prolonged release suspension that lasts up to 12 hours per dose. In addition, this medicine does not treat cough caused by asthma or smoking.

When this drug is administered in doses far in excess of those considered therapeutic for a persistent cough, it is known to produce altered time perception, increased perceptual awareness, and visual hallucinations.

More importantly, people who abuse this drug are prone to lethargy, hyperexcitability, slurred speech, ataxia (lack of voluntary coordination of muscle movements), hypertension, sweating, and nystagmus (rapid, involuntary, and repeated eye movements).

Since this type of medication is quite effective, they are usually kept behind the counter in drugstores, but can still be found on the shelves in some stores.

Delsym vs. Robitussin – Comparison Side effects and precautions

The side effects may include:

Slowed breathing;
stomach pain;
blurred vision;
unsteady gait;
difficulty passing urine.

Symptoms of overdose may include

swelling of the face, mouth, tongue, lips, or throat;
unusual hoarseness;
difficulty breathing;
swollen, red, blistered, or peeling skin;
tightness in the chest or throat;
irritability, restlessness, nervousness and unusual excitement.
SEE ALSO: Phenylephrine vs. pseudoephedrine – Side effects and indications
Pregnancy and breastfeeding
Talk to your doctor or health care professional before using this medicine if you are breastfeeding, because there are no conclusive studies on whether this medicine can pass into breast milk and harm the baby.

Talk to your doctor or health care professional before you use this medicine if you are pregnant. There are no conclusive studies on whether this medicine can harm your unborn child.

Do not use this medicine in children under 6 years of age unless your doctor or health care professional tells you to.

Interactions with other medicines

A dangerous drug interaction could occur if you use this medication and if you have taken an MAO inhibitor in the past two weeks. Monoamine oxidase inhibitors are the first class of antidepressants developed and include – linezolid, isocarboxazide, phenelzine, methylene blue injection, selegiline, rasagiline, and tranylcypromine.

Keep this medicine out of the reach of children and store at room temperature.


It is the brand name for guaifenesin (also known as glyceryl guaiacolate), an expectorant. However, this drug is not typically used for persistent cough due to asthma, smoking, emphysema, and coughing with a lot of mucus.

Robitussin DM contains two active ingredients:

Guaifenesin – it is an expectorant drug that helps to relieve congestion in the throat and chest and thus relieves coughing through the mouth;
dextromethorphan – it is a cough suppressant that affects the signals in the brain that trigger the cough reflex. In addition, dextromethorphan helps to loosen and detach mucus, especially in combination with guaiphenesin.
It is available in maximum strength, normal strength, children’s formulations and sugar-free. It is also available in liquid form which you can take by mouth.

SEE ALSO: E337 – Potassium sodium tartrate: Use and side effects
Talk to your healthcare provider if your cough does not go away after a week. Store this medicine in a cool, dry place.

Side effects and precautions

The common side effects may include

upset stomach;
dry mouth;
Severe side effects (very rare) may occur:

skin rash;
severe dizziness;
shallow breathing;
weak pulse;
slow heart rate;
tingling under the skin;
less urination than usual;
unusual behavior;
unusual thoughts;

If you have signs and symptoms of an allergic reaction, seek urgent professional medical attention. These symptoms include: difficulty breathing, hives, swelling of the lips, face, throat and tongue.

It is not known if this medicine will have adverse effects on an unborn child. Therefore, be on the safe side and avoid it. More importantly, it is not recommended to use this medicine:

if you are 4 years old or younger;
if you have ever had Stevens-Johnson syndrome, a rare but serious condition that causes blisters on the skin;
if you are breast-feeding;
if you have high blood pressure;
if you have diabetes;
if you have thyroid disease;
if you are taking monoamine oxidase inhibitors.

Delsym vs. Robitussin – What is the best treatment for persistent cough?

Both are advertised as Delsym drugs that act as cough suppressants. The problem is that both have many side effects and their effectiveness is almost exclusively anecdotal.

According to a study carried out by the Children’s Hospital in 2010, for example, a 2.5 mL dose of honey before bedtime has a soothing effect on coughs caused by viral infections of the upper respiratory tract compared to dextromethorphan doses.