NEW YORK -- April 21, 2008 -- According to a review in the latest issue of The Cochrane Library, possible adverse events may outweigh the benefits of antihistamines when used to treat chronic cough in children. This review adds to the growing body of evidence casting doubt on the use of a variety of medicines for children.
The authors examined 5 studies involving nearly 1,000 children, with ages ranging from 6 months to 17 years. Many children had allergies to grass, pollen, or dust mites, or they had a family history of allergy.
Two of the studies the authors reviewed were larger studies that showed significant improvement both in children who took antihistamines and those who took placebo, but no significant difference was seen between the 2 groups.
A smaller study involving 20 school-aged children found that cetirizine (Zyrtec) clinically improves cough due to pollen allergy. In that study, the antihistamine was significantly more effective than placebo in reducing chronic cough in children with allergies.
Another study examined the use of ketotifen (Zaditen) to minimise the frequency of asthma attacks in 113 infants ranging in age from 6 months to 36 months. After a 4-week, no-medication baseline, infants received a placebo or ketotifen for 16 weeks. The researchers concluded that they were "unable to show a therapeutic advantage of ketotifen over placebo."
The reviewers noted that the effectiveness of these medications should be weighed against their reported side effects, especially in young children. Most of the events reported in these studies were minor, and the most common events were irritability and gastrointestinal upset. Four children were withdrawn from 1 study, and 12 other children felt drowsy after taking the study medication.
A small trial involving cetirizine had reported that there were no adverse effects.
However, because not all antihistamines are created equal, older antihistamines may have more anticholinergic activity, said Richard Irwin, MD, Professor, University of Massachusetts Medical School, Worcester, Massachusetts.
"These older drugs, therefore, can work when the cause of the upper airway cough is not due to allergies, and they can also work if the cause of the cough is due to allergies," Dr. Irwin said. "On the other hand, because the new drugs such as cetirizine or loratadine don't have much anticholinergic activity to speak of, they will only work if the cause of the upper airway cough is due to allergies."
Newer antihistamines "have been shown to be of help in children with allergic rhinitis," Dr. Irwin said. "The literature supports using these specific antihistamines when children have cough in association with seasonal allergies that involve the nose."
In children, it is important to elucidate the cause of the cough, said lead reviewer Anne B. Chang, PhD, Royal Children's Hospital, Brisbane, Australia, and Professor, Menzies School of Health Research, Queensland, Australia. She recommends that physicians talk to parents about their fears and concerns and says that parents who smoke should stop. When Dr. Chang's patients show up with a nonspecific cough, she says she uses a cautious, wait-see-and-review approach.
The reviewers concluded, "In contrast to recommendations in adults with chronic cough, antihistamines cannot be recommended as empirical therapy for children with chronic cough."
SOURCE: The Cochrane Library, 2008, Issue 2
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