Published: 4 September 2025

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Attention: Safety of medicines used to treat ADHD in adults

Published: 4 September 2025
Prescriber Update 46(3): 41–44
September 2025

The number of adverse reaction reports for attention-deficit hyperactivity disorder (ADHD) medicines in adults increased in 2024 compared to previous years. In addition, on 1 February 2026, changes to who can prescribe stimulant medicines for ADHD will come into effect.¹ These changes are expected to increase access to ADHD medicines.

With these circumstances in mind, we considered it timely to discuss the safety of medicines used to treat ADHD in adults.

ADHD in adults²

Attention deficit hyperactivity disorder (ADHD) in adults is characterised by symptoms of inattention, impulsivity and restlessness resulting in functional impairment. Functional impairment includes difficulties performing everyday tasks, and reduced ability to engage in work, education or social activities.

Executive dysfunction (difficulties with planning, organising, and prioritising and completing tasks) and emotional dysregulation (difficulties responding to and managing emotions) are also commonly seen.

The predominant feature of ADHD in adults is inattention, which differs from children, where hyperactivity and impulsivity are more typical features.

Medicines used to treat ADHD in adults

Stimulant medicines block the reuptake of noradrenaline and dopamine.^3-7 In New Zealand, lisdexamfetamine and methylphenidate are the stimulant medicines approved for the treatment of ADHD in adults. They are indicated as an integral part of a total treatment programme that may include other measures (psychological, educational and social) for patients with this syndrome.^3–9

Atomoxetine is a non-stimulant medicine that inhibits the reuptake of noradrenaline.^10-12 It is indicated for the treatment of ADHD in adults particularly if stimulants are contraindicated, following treatment failure with stimulants (eg, inadequate response, problematic adverse effects), or when there is a significant risk of misuse of stimulants.^9,12

Lisdexamfetamine, methylphenidate and atomoxetine have similar safety considerations. These are summarised in Table 1 and include psychiatric effects, cardiovascular effects, risk of seizures and serotonin syndrome.

Table 1: Safety considerations when prescribing lisdexamfetamine, methylphenidate, or atomoxetine in adults for ADHD*

Warning or precaution	Comments
Psychiatric disorders
Comorbid psychiatric disorders	Comorbidity of psychiatric disorders in ADHD is common. Consider the patient’s personal and family psychiatric history when prescribing. For example, treatment of ADHD with stimulants should not be initiated in patients with acute psychosis, acute mania or acute suicidality.
Suicidal tendency	Do not initiate treatment in patients with signs of suicidal tendency. Monitor patients for signs of suicidality, particularly during the first few months of treatment and with any dose changes.
Tics or Tourette’s syndrome	Do not use lisdexamfetamine in individuals with tics or Tourette’s syndrome. Methylphenidate is associated with the onset or exacerbation of motor and verbal tics, including worsening of Tourette’s syndrome. There have been reports of tics with atomoxetine.
Aggressive behaviour	Monitor patients for onset or exacerbation of aggressive behaviour which may occur during treatment. Dose increases or decreases may be needed.
Cardiovascular disease
Cardiovascular disorders	Sudden deaths have been reported with the use of stimulant medicines in patients with structural cardiac abnormalities, but a causal relationship has not been established. Adults with structural cardiac abnormalities or other serious cardiac problems (eg, cardiomyopathy, heart rhythm abnormalities) should not be treated with these medicines. Before prescribing, assess for pre-existing cardiovascular disorders, family history of sudden death and arrythmias, and measure blood pressure and heart rate. Regularly review blood pressure and cardiovascular status during treatment.
Increases in blood pressure or heart rate	Some patients can have clinically relevant increases in blood pressure or heart rate. Be careful when treating patients whose underlying medical conditions might be compromised by increases in blood pressure or heart rate.
Other
Seizures	Stimulant medicines may lower the convulsive threshold in patients with or without prior history of seizure. Seizures have been reported during atomoxetine treatment.
Serotonin syndrome	Serotonin syndrome may occur following coadministration with serotonergic medicines, including selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs). If coadministration cannot be avoided, exercise caution and monitor for signs and symptoms of serotonin syndrome.
Risk of abuse (stimulant medicines)	There is potential for misuse, abuse, dependence, or diversion of stimulant medicines. Assess the risk of abuse before prescribing and monitor for signs of abuse and dependence during treatment.
Liver injury (atomoxetine)	Reports indicate atomoxetine may cause severe liver injury, including acute liver injury, elevated hepatic enzymes, and bilirubin with jaundice.

* Not an exhaustive list. Refer to the data sheets for full information.

Sources: Lisdexamfetamine, methylphenidate and atomoxetine data sheets, available at www.medsafe.govt.nz/Medicines/infoSearch.asp (accessed 25 June 2025).

New Zealand case reports

Between 1 January 2021 and 30 June 2025, there were 20 adverse reaction cases reporting methylphenidate (15 cases), atomoxetine (4 cases), or lisdexamfetamine (1 case) as the suspect medicine in an adult aged 18 years or older.

In these 20 cases:

• the median age was 34.5 years (range 19 to 66 years)
• there was a peak of 10 cases reported during 2024
• nine cases reported reactions in the psychiatric disorders group, including two cases reporting anxiety, two cases reporting both suicidal ideation and depression, and one case reporting suicidal ideation
• other reactions with two or more reports were headache, hyperhidrosis, and therapeutic response decreased.

Further information

More information on ADHD in adults is available from the following links:

• Medicine data sheets
• ADHD in adults | Aroreretini ki ngā pakeke (Healthify)
• Medicines for ADHD in adults (Healthify)
• Changes to the regulatory and funding restrictions for stimulant medicines for ADHD
• Australasian ADHD Professionals Association (AADPA) guideline

References

1. New Zealand Government. 2025. Restriction on the supply of dexamfetamine, lisdexamfetamine, and methylphenidate – Approval to prescribe, supply and administer. New Zealand Gazette 24 June 2025. URL: gazette.govt.nz/notice/id/2025-go3319 (accessed 25 June 2025).
2. Bukstein OG, Brent DA, Friedman M. 2025. Attention deficit hyperactivity disorder in adults: Epidemiology, clinical features, assessment, and diagnosis. In: UpToDate 7 February 2025. URL: www.uptodate.com/contents/attention-deficit-hyperactivity-disorder-in-adults-epidemiology-clinical-features-assessment-and-diagnosis (accessed 25 June 2025).
3. Takeda New Zealand Limited. 2024. Vyvanse New Zealand Data Sheet 22 August 2024. URL: www.medsafe.govt.nz/profs/Datasheet/v/vyvansecap.pdf (accessed 25 June 2025).
4. Janssen-Cilag (New Zealand) Ltd. 2024. Concerta Extended Release Tablets New Zealand Data Sheet 3 July 2024. URL: www.medsafe.govt.nz/profs/Datasheet/c/Concertatab.pdf (accessed 25 June 2025).
5. Teva Pharma (New Zealand) Limited. 2024. Methylphenidate Extended Release (Teva) New Zealand Data Sheet 30 August 2024. URL: www.medsafe.govt.nz/profs/Datasheet/m/methylphenidateTevatab.pdf (accessed 25 June 2025).
6. Novartis New Zealand Limited. 2024. Ritalin and Ritalin LA New Zealand Data Sheet 30 January 2024. URL: www.medsafe.govt.nz/profs/Datasheet/r/RitalintabSRtabLAtab.pdf (accessed 25 June 2025).
7. AFT Pharmaceuticals Ltd. 2024. Rubifen LA New Zealand Data Sheet 22 January 2024. URL: www.medsafe.govt.nz/profs/Datasheet/r/RubifenLACap.pdf (accessed 25 June 2025).
8. Brent DA, Bukstein OG, Solanto MD. 2025. Attention deficit hyperactivity disorder in adults: Treatment overview. In: UpToDate 20 June 2025. URL: www.uptodate.com/contents/attention-deficit-hyperactivity-disorder-in-adults-treatment-overview (accessed 25 June 2025).
9. ADHD Guideline Development Group. 2022. Australian evidence-based clinical guideline for attention deficit hyperacitivity disorder (ADHD). Melbourne: Australasian ADHD Professionals Association. Available at: adhdguideline.aadpa.com.au/ (accessed 3 July 2025).
10. Arrotex Pharmaceuticals (NZ) Limited. 2021. Apo-Atomoxetine New Zealand Data Sheet 4 November 2021. URL: www.medsafe.govt.nz/profs/Datasheet/a/apoatomoxetinecap.pdf (accessed 25 June 2025).
11. Arrotex Pharmaceuticals (NZ) Limited. 2023. Atomoxetine (Arrotex) New Zealand Data Sheet. 26 April 2023. URL: www.medsafe.govt.nz/profs/Datasheet/a/AtomoxetineGPcap.pdf (accessed 25 June 2025).
12. New Zealand Formulary (NZF). 2025. NZF v156: CNS stimulants and drugs used for attention deficit hyperactivity disorder 1 June 2025. URL: nzf.org.nz/nzf_2328 (accessed 25 June 2025).