Management of disorders of sedating antihistamine use

Overview of substance use and addictive behaviours explains key principles of care for a person with a disorder of substance use. Establishing a therapeutic relationship that engages the person (and ideally those close to them) is central to the management of substance dependence.

Specialist advice on any aspects of care for patients with any disorder of substance use is available and contact is encouraged; see Contact details for substance use clinical advisory services for clinicians.

Consider specialist referral to manage withdrawal if a patient has severe withdrawal symptoms or comorbid conditions, especially psychosis or polysubstance use (use of more than one substance).

Weaning of sedating antihistamines can usually be performed in an outpatient setting. Abruptly stopping a sedating antihistamine after prolonged use (even at recommended doses) can cause unplanned withdrawal, but it is rarely severe. Patients dependent on very high doses of sedating antihistamines with anticholinergic properties (eg diphenhydramine) may require hospital admission for severe symptoms of cholinergic reboundBonham, 2009, such as urinary urgency, tachycardia, orthostatic hypotension, severe anxiety or severe insomniaNSW Therapeutic Advisory Group, 2018.

Evidence to guide weaning regimens for sedating antihistamines is limited; advice in these guidelines is based on the consensus view of the Addiction Guideline Group, extrapolating from approaches used for managing polypharmacy in older patients. The New South Wales Therapeutic Advisory Group (TAG) deprescribing guide for sedating antihistamines can be downloaded at the TAG website; this outlines weaning schedules, monitoring advice and alternative management for those who were using the sedating antihistamine to manage allergy or itch.

Offer alternative strategies (which may include group or individual psychosocial support) for managing other factors that precipitate or perpetuate prolonged use of sedating antihistamines, such as insomnia and anxiety.

Substance use can pose a risk of acute harm to the person (such as self-harm, falls and other accidents, suicide) and others (through impacts on driving, childcare, fitness to work and acute behavioural disturbances). For advice on managing these risks, see Ensuring the safety of a person with a disorder of substance use or addictive behaviour. For harm reduction measures to consider for any person with a disorder of substance use or addictive behaviour, see Harm reduction in substance use and addictive behaviours.

Elements of long-term management relevant to all disorders of substance use are covered in Long-term care in disorders of substance use and addictive behaviours.

Considerations for specific populations may be relevant in managing disorders of sedating antihistamine use.