Robitussin, an over-the-counter medicine made by Pfizer, Inc. to treat cough, runny nose, and/or chest congestion, comes in two versions: regular and DM. Reading the label can give you a basic idea of the differences between the two, but you should also understand the medical implications of the additional ingredients in Robitussin-DM.

According to Drugs.com, the generic name for Robitussin is dextromethorphan. Robitussin-DM is a combination of dextromethorphan and guaifenesin, another drug.

Dextromethorphan also goes under a number of other brand names, including Vicks 44 Cough Relief, Pediacare, Pediacare Long-Acting Cough, Children's Pedia Care, and Simply Cough.

The combination of dextromethorphan and guaifenesin algo goes under the brand names that include Mucinex DM, Mucinex Children's Cough, Drituss DM, Robitussin Cough & Congestion, and others.

According to Drugs.com, dextromethorphan is a cough suppressant that affects the signals in the brain that trigger the cough reflex. Dextromethorphan does not treat coughs that are the result of smoking, asthma, or emphysema.

Dextromethorphan and guaifenesin combined treat cough and chest congestion that is caused by the common cold, infections, or allergies.

Guaifenesin is an expectorant, which means that it helps loosen congestion in your chest and throat, making it easier to cough out through your mouth.

Asthma (and other respiratory illness) sufferers should be aware that, according to Drugs.com, dextromethorphan decreases coughing but makes it difficult to get rid of the mucus that collects in the lungs and airways. It also can result in slow breathing.

Diabetics should watch out for products that contain sugar, as some cough syrups do, since these formulations may affect glucose levels.

Consumers with liver disease should consult with a physician because dextromethorphan may build up in the body and cause additional health issues.

Avoid using additional over-the-counter cough or cold medications, diet pills, ADHD medications, or other stimulants while taking products that contain dextromethorphan or dextromethorphan with guaifenesin, since the risk of possible side effects (e.g., increased heart rate) is increased in these cases. Drugs.com advises consumers to seek the advice of their doctor or pharmacist if use of cough or cold medications is necessary.

According to Drugs.com, studies in women suggest that dextromethorphan poses minimal risk to infants when the mother uses it while breastfeeding.

Since it is currently unknown whether or not guaifenesin poses harm to unborn babies, or whether or not it passes through breast milk, consumers are advised to consult their physicians prior to consuming Robitussin-DM or similar products.

Although only a rare occurrence, dextromethorphan has become habit-forming in some users who consume more than the recommended dosage for prolonged periods.