Cough Suppressants

Definition

Cough suppressants are medicines that prevent or stop coughing.

Purpose

Cough suppressants act on the center in the brain that controls the cough reflex. They are meant to be used only to relieve dry, hacking coughs associated with colds and flu. They should not be used to treat coughs that bring up mucus or the chronic coughs associated with smoking, asthma, emphysema or other lung problems.

Many cough medicines contain cough suppressants along with other ingredients. Some combinations of ingredients may cancel each other's effects. One example is the combination of cough suppressant with an expectorant—a medicine that loosens and clears mucus from the airways. The cough suppressant interferes with the ability to cough up the mucus that the expectorant loosens.

Description

The cough suppressant described here, dextromethorphan, is an ingredient in many cough medicines, such as Vicks Formula 44, Drixoral Cough Liquid Caps, Sucrets Cough Control, Benylin DM and some Robitussin products. These medicines come in capsule, tablet, lozenge, and liquid forms and are available without a physician's prescription.

Recommended dosage:

Regular (short-acting) capsules, lozenges, syrups, or tablets:

• adults and children over 12: 10-30 mg every four to eight hours, as needed
• children six to 12: 5-15 mg every four to eight hours, as needed
• children two to six: 2.5-7.5 mg every four to eight hours, as needed (Children under six should not be given lozenges containing dextromethorphan because of the high dose of dextromethorphan in each lozenge.)
• children under two: check with child's physician

For extended-release oral suspension:

• adults and children over 12: 60 mg every 12 hours, as needed
• children six to 12: 30 mg every 12 hours, as needed
• children two to six: 15 mg every 12 hours, as needed
• children under two: check with child's physician

Precautions

Do not take more than the recommended daily dosage of dextromethorphan.

Dextromethorphan is not meant to be used for coughs associated with smoking, asthma, emphysema, chronic bronchitis, or other lung conditions. It also should not be used for coughs that produce mucus.

A lingering cough could be a sign of a serious medical condition. Coughs that last more than seven days or are associated with fever, rash, sore throat, or lasting headache should have medical attention. Call a physician as soon as possible.

People with phenylketonuria should be aware that some products with dextromethorphan also contain the artificial sweetener aspartame, which breaks down in the body to phenylalanine.

Anyone who has asthma or liver disease should check with a physician before taking dextromethorphan.

Women who are pregnant or breastfeeding or who plan to become pregnant should check with their physicians before taking dextromethorphan.

The dye tartrazine is an ingredient in some cough suppressant products. This dye causes allergic reactions in some people, especially those who are allergic to aspirin.

Side effects

Side effects are rare, but may include nausea, vomiting, stomach upset, slight drowsiness, and dizziness.

Interactions

Patients who take monoamine oxidase inhibitors (MAO inhibitors) should be aware that the co-administration of products containing dextromethorphan can cause dizziness, fainting, fever, nausea and possibly coma. Do not take dextromethorphan unless a physician permits the use of the two drugs together.

When dextromethorphan is taken with medicines that cause drowsiness, this effect may be enhanced.

KEY TERMS

Asthma— A disease in which the air passages of the lungs become inflamed and narrowed.

Bronchitis— Inflammation of the air passages of the lungs.

Chronic— A word used to describe a long-lasting condition. Chronic conditions often develop gradually and involve slow changes.

Emphysema— An irreversible lung disease in which breathing becomes increasingly difficult.

Mucus— Thick fluid produced by the moist membranes that line many body cavities and structures.

Phenylketonuria (PKU)— A genetic disorder in which the body lacks an important enzyme. If untreated, the disorder can lead to brain damage and mental retardation.

Cough suppressants

Definition

Cough suppressants are medicines that prevent or stop a person from coughing.

Description

Cough suppressants act on the center in the brain that controls the cough reflex. They are meant to be used only to relieve dry, hacking coughs associated with colds and flu. They should not be used to treat coughs that bring up mucus or the chronic coughs associated with smoking, asthma , emphysema, or other lung problems.

The most effective cough suppressants are narcotics. Heroin, which is not approved for medicinal use in the United States, and codeine have been widely used to stop coughs. These compounds, in addition to relieving coughs, also relieve pain , cause sedation, and are addictive. The most popular drug in this class is dextromethorphan, which is quite safe and is available without prescription. Dextromethorphan is an ingredient in most over-the-counter cough preparations:

• Vicks Formula 44
• Drixoral Cough Liquid Caps
• Sucrets Cough Control
• Benylin DM

The letters DM in a product's name normally indicates the presence of dextromethorphan, but it is always best to read the ingredients. Dextromethorphan works best in liquid formulations but is also available in capsules, lozenges, and tablets.

General use

Dextromethorphan is used for the temporary relief of coughs caused by minor throat and bronchial irritation such as may occur with common colds or with inhaled irritants. Dextromethorphan is most effective in the treatment of chronic, nonproductive cough.

Dextromethorphan has been reported to be effective in reversing some of the adverse effects of methotrexate, a drug that has found use in many conditions including cancer, psoriasis , and some types of arthritis.

Precautions

Lozenges containing dextromethorphan hydrobromide should not be used in children younger than six years of age. Liquid-filled capsules containing the drug should not be used in children younger than 12 years of age.

Dextromethorphan is not meant to be used for coughs associated with asthma, chronic bronchitis , or other lung conditions. It should not be used for coughs that produce mucus.

A lingering cough could be a sign of a serious medical condition. Patients with a cough that lasts more than seven days or is associated with fever , rash, sore throat , or lasting headache should have medical attention. Parents should call a physician as soon as possible if their child has these symptoms.

Side effects

Dextromethorphan rarely causes side effects but has been reported to cause dizziness , drowsiness, and stomach upset. There have been rare reports of vomiting caused by dextromethorphan.

Although dextromethorphan is very safe, it can cause problems when taken in too large a dose. In overdose, dextromethorphan can cause extreme dizziness, shallow breathing, and coma.

Interactions

Dextromethorphan has no clinically significant interactions with medications that are likely to be given to children. However, dextromethorphan should not be used in combination with narcotic analgesics such as meperidine or codeine, since dextromethorphan will increase the side effects of the analgesic.

Parental concerns

Lozenges containing dextromethorphan hydrobromide should not be used in children younger than six years of age. Liquid-filled capsules containing the drug should not be used in children younger than 12 years of age. Doses must be measured carefully. Measuring teaspoons should be used in place of household teaspoons.

Adolescent behavior must be observed, since some multi-ingredient over-the-counter cough remedies have become drugs of abuse. While these products are not addictive, they are toxic when misused.

KEY TERMS

Chronic —Refers to a disease or condition that progresses slowly but persists or recurs over time.

Narcotic —A drug derived from opium or compounds similar to opium. Such drugs are potent pain relievers and can affect mood and behavior. Long-term use of narcotics can lead to dependence and tolerance. Also known as a narcotic analgesic.

Nonproductive —A cough in which no mucus is coughed up, also called dry cough.

See also Expectorants.

Resources

BOOKS

Beers, Mark H., and Robert Berkow, eds. The Merck Manual, 2nd home ed. West Point, PA: Merck & Co., 2004.

Mcevoy, Gerald, et al. AHFS Drug Information 2004. Bethesda, MD: American Society of Healthsystems Pharmacists, 2004.

Siberry, George K., and Robert Iannone, eds. The Harriet Lane Handbook, 15th ed. Philadelphia: Mosby Publishing, 2000.

PERIODICALS

Baker, S. D., and D. J. Borys. "A possible trend suggesting increased abuse from Coricidin exposures reported to the Texas Poison Network: comparing 1998 to 1999." Veterinary and Human Toxicology 44, no. 3 (June 2002): 169–71.

Kirages, Thomas J., Harsh P. Sulé, and Mark B. Mycyk. "Severe manifestations of coricidin intoxication." American Journal of Emergency Medicine 21, no. 6 (October 2003): 473–5.

Schroeder, Knut, and T. Fahey. "Over-the-counter medications for acute cough in children and adults in ambulatory settings." Cochrane Database of Systematic Reviews 3 (2001): CD001831.

ORGANIZATIONS

American Academy of Emergency Medicine. 555 East Wells Street, Suite 1100, Milwaukee, WI 53202–3823. Web site: <www.aaem.org>.

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: <www.aap.org>.

WEB SITES

"Drug Information." MedlinePlus. Available online at <www.nlm.nih.gov/medlineplus/druginfo/uspdi/202187.html> (accessed October 17, 2004).

"Over-the-Counter Drug Products." Center for Drug Evaluation and Research. Available online at <www.fda.gov/cder/Offices/OTC/default.htm> (accessed October 17, 2004).

"Prescription Drug Abuse." MedlinePlus Available online at <www.nlm.nih.gov/medlineplus/prescriptiondrugabuse.html> (accessed October 17, 2004).

Nancy Ross-Flanigan Samuel Uretsky, PharmD