Neuropsychiatric symptoms such as aggression, suicidal ideation, abnormal behaviour and nightmares are amongst the most common adverse drug reactions reported in children and adults taking montelukast (Singulair) for their asthma.

A study of both Dutch and WHO Global pharmacovigilance databases found odds ratios as high as 24.99 for aggression, 20.43 for suicidal ideation, 34.05 for abnormal behavior and 22.48 for nightmares.

In children under 19 years of age, the odds ratio was 29.77 for aggression, 38.27 for suicidal ideation and 78.04 for nightmares.

Other common reactions were headaches, insomnia and anxiety in all ages while serious adverse events included chest pain and allergic granulomatous angiitis. Two deaths were identified in the Dutch database.

Researchers said the findings reinforced the need for clinicians to discuss the possibility of adverse reactions with their patients and parents.

Commenting on the study, paediatric respiratory physician Professor Adam Jaffe said the side effects were still fairly rare.

“There were only 331 reports in Dutch study. The TGA in Australia has reported less than 100 in the context of thousands of children getting the medication.”

 “I don’t think we’re seeing more side effects but we are becoming more aware of the importance of them. The message is there is definitely an association, that it is rare, but parents need to know about it and consider it.”

Professor Jaffe, associate director of research for the Sydney Children’s Hospitals Network, told the limbic a recent Canadian study provided some reassurance to prescribers and patients alike.

“They found that if you are going to see side effects, you normally see them within two weeks but importantly, if you stop the medication, side effects disappear within a couple of days.”

“So we know these side effects occur, we know they are mostly sleep disturbances, behavior and headaches, and that parents need to look out for them if it occurs.”

Professor Jaffe said montelukast was still commonly used despite widespread media coverage of the potential side effects, especially in children.

“Montelukast is an incredibly important medication which is highly effective in some children. We mustn’t be discounting a good medication with fantastic effects in some patients because of side effects they may not get.”

He said upcoming versions of the Australian Asthma Handbook would remind physicians to tell their patients about the potential side effects.

“If they see a sudden change in their child’s behavior within a couple of weeks of starting montelukast, to be aware that might be a potential side effect.”

MSD Australia told the limbic the approved Product Information and Consumer Medicines Information for the drug provided relevant information regarding neuropsychiatric adverse events.

“In the ongoing review of the safety profile of Singulair/Lukair, MSD has not identified any additional safety information to communicate to prescribers and patients.”