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You are working a moderately busy evening shift in the pediatric ED. The medical student has just finished presenting the kid he saw in bed eight. The patient is an 8-year-old boy with known asthma, here with an acute exacerbation in the setting of a mild upper respiratory infection. Based on his asthma severity score he is likely to go home, but he is currently wheezing and needs treatment. The student proposes inhaled albuterol and atrovent, which sounds like a good plan. Then the conversation turns to steroids. The student wants to order a dose of prednisolone in the ED and then send the patient home with 4 more days of prednisolone to complete a 5-day course. It is what he has seen his preceptors do on other occasions. You suggest a single dose of dexamethasone instead. The student wants to know what evidence supports this therapy and why you are choosing this approach.

In your U.S. emergency practice, the common treatment for mild-moderate asthma is 2 mg/kg of prednisone/prednisolone orally in the acute setting, followed by 4 additional days of 1 mg/kg twice daily. This does not always go as planned, however. In 2001, Cooper and Hickson published a of 6,035 Tennessee Medicaid patients ages 2 to 17 years either seen in the ED or admitted to the hospital with asthma. These patients were then sent home with prescriptions for prednisone/prednisolone. The study found that only 44.8% of the children discharged from the ED filled the prescription within 7 days, and only 55.5% of the children discharged from the hospital filled the prescription within 7 days. This is not the only argument against prednisone/prednisolone. Patients frequently complain about the bitter taste of the drug and will sometimes experience vomiting after taking it.

Dexamethasone is five to six times more potent than prednisone/prednisolone, and is more palatable and associated with less vomiting. The half-life of prednisone/prednisolone is 12 to 36 hours, while the half-life of dexamethasone is 36 to 72 hours. But prednisone/prednisolone has been the standard therapy for many years. What is the evidence that dexamethasone is as effective?

In 1997, Jean Klig and colleagues published a small involving 42 ED patients, ages 3-16 with asthma, who were well enough to be discharged home. They compared a single dose of 0.3 mg/kg IM dexamethasone versus 2 mg/kg of oral prednisone for 3 days. Patients were followed up after 5 days either in clinic or by telephone. All of the patients had clinical improvement in their asthma symptoms, and there were no hospitalizations. Based on this pilot study, the authors concluded that a single dose of IM dexamethasone given in the ED produced results similar to those of 3 days of prednisone.

In 2000, Gries and colleagues of dexamethasone versus oral prednisone. This was done in a clinic setting with children ages 6 months to 7 years; 16 patients were randomized to receive a single dose of 0.4 mg/kg of dexamethasone, and 17 patients were randomized to receive 5 days of 2 m/kg of oral prednisone. Families kept a symptom diary, and patients were reassessed in clinic. All patients improved in 5 days, and there was no difference between groups.

These were both small studies. In 2007, Gordon and colleagues published a of IM dexamethasone versus oral prednisolone. Patients were 18 months to 7 years old with asthma in an ED setting; 88 were treated with 0.6 mg/kg IM dexamethasone as a single dose, and 93 were treated with 2 mg/kg of oral prednisolone for 5 days. Patients were reassessed 4 days later using an asthma severity score. Again, there was no significant difference between the two groups.

At this point the medical student does not appear convinced. After all, two of these studies had pretty small numbers. Shots hurt and children and their parents are well aware of that. Besides, two of those studies you cited included children less than 2 years of age. A lot of clinicians are uncomfortable diagnosing asthma in children that young. What if they had bronchiolitis instead? That doesn't respond to steroids. Wouldn't that bias your hypothesis toward the null -- that is, no difference between groups?

You concede the student's points. However, there are three additional randomized clinical trials that have looked at oral dexamethasone, not IM. None of them included children less than 2 years of age. What have those studies shown?

In 2001, Qureshi and others published a of 2- to 18-year-olds with asthma in an ED setting. The purpose was to compare 2 days of oral dexamethasone dosed as 0.6 mg/kg with 5 days of oral prednisone/prednisolone dosed as 2 mg/kg in the ED, then 1 mg/kg/day for 4 days; 272 children were analyzed in the dexamethasone group and 261 in the prednisone/prednisolone group. There was no significant difference between the groups in relapse rates, hospitalization rate, or symptom persistence. The group receiving prednisone/prednisolone had more vomiting in the ED, more noncompliance with medication, and missed more days of school.

In 2006, Altamimi and others published another prospective, in an ED setting. In this study of children age 2 to 16 years, a total of 56 were given one dose of oral dexamethasone of 0.6 mg/kg and 54 were given 5 days of oral prednisone/prednisolone at 2 mg/kg/day. Patients were evaluated by phone 48 hours after leaving the ED, and then had a revisit at 5 days post discharge. The primary outcome was return of self-assessment score to baseline. There was no significant difference between the two groups.

In 2008, Greenberg and colleagues published in an ED setting, looking at 38 patients ages 2 to 18 who received a 5-day course of 2 mg/kg of oral prednisone compared with 51 who had a 2-day course of oral 0.6 mg/kg dexamethasone. The follow-up medications were given in blister packs to ensure compliance. The outcomes of interest were relapse within 10 days or vomiting in the ED. There was no significant difference between the two groups.

The most to address the question of oral dexamethasone versus prednisone/prednisolone was published by Cronin and colleagues in 2016. This was done in an ED setting in Ireland and involved children ages 2 to 16 years; 245 patients were analyzed. The dosing schedule was different from the prior studies of oral dexamethasone. The dose of dexamethasone was 0.3 mg/kg -- which is half of what was given in the other trials -- and the dose of prednisolone was 1 mg/kg -- again half the dose in the other trials. The dexamethasone was given as a single dose in the ED, and the prednisolone was given over 3 days, as opposed to 5 days in the other trials. The primary outcome was asthma scores on day 4, which were no different between the two groups. Hospitalization rates and unscheduled return visits were also not different; 14 children vomited with the prednisolone versus none of the dexamethasone patients.

The student looks convinced. You probably had him when you quoted the rate of unfilled prescriptions, but you definitely won him over when you told him it could be given as a single oral dose in the ED. Some caution is needed, however. Although there are currently six randomized trials showing dexamethasone to be just as good as prednisone/prednisolone, three gave the dexamethasone IM, one gave 2 days of oral dexamethasone, and only two of the trials used a single ED dose. Of those two, one was small, and the other used lower doses than are standard in the U.S.

So the verdict is probably still out for now. But it is an option worth considering. Based on the dose used in four of the six trials reviewed, you order 0.6 mg/kg of oral dexamethasone (maximum 15-18 mg) and move on to the next patient.

Amy Levine, MD, is a professor of pediatrics in the Division of Pediatric Emergency Medicine at the University of North Carolina. A version of this article originally appeared at .