Atomoxetine

Atomoxetine works differently from stimulant ADHD medicines, so the things to look out for are slightly different. The points below summarise how atomoxetine behaves in the body, how it can interact with other medicines, and what types of monitoring are recommended during treatment. This can help you understand what to expect, and what to discuss with your prescribing clinician if anything changes.

Lack of addictive potential

Atomoxetine is a non stimulant medicine that is not addictive. It is often the preferred choice for people with ADHD who also have Substance Use Disorder, because it does not raise dopamine levels in brain reward pathways (23, 22, 24).

Effect on coexisting conditions

Although atomoxetine increases noradrenaline, studies show that it does not worsen other psychiatric or behavioural conditions that often occur alongside ADHD, and in some cases these symptoms improve (23). This includes:

• Conduct Disorder (CD) and Oppositional Defiant Disorder (ODD) in children

• Anxiety or depression in some individuals

• Autistic spectrum traits or tic disorders

Interpersonal variability in treatment response

People metabolise atomoxetine at different speeds. This affects how well the medicine works and what dose is needed. CYP2D6 genotype plays a key role in these differences, which is why dose personalisation is important (25).

Monitoring requirements

Children should be monitored for growth, and both children and adults should be monitored for new psychiatric symptoms and for any signs of suicidal thoughts during the early stages of treatment (22).

Interaction with other medicines

Medicines that inhibit CYP2D6, especially SSRIs, can raise atomoxetine levels in the bloodstream (12, 22). Atomoxetine can also interact with MAO inhibitors. These interactions can be clinically significant, so co prescribing or switching between these treatments should be supervised.

Atomoxetine Side Effects

Although atomoxetine raises noradrenaline, it usually produces only mild increases in heart rate and blood pressure (24). Significant increases are mainly seen in toxicity (22). Moderately elevated BP/HR occurs in around 8–12% of children (24).

Common Side Effects

The most common side effects are (24, 22):

• Nausea, vomiting, loss of appetite

• Daytime drowsiness (more common than insomnia)

• Headache

Although atomoxetine usually improves co-existing conditions, in a small minority it can cause anxiety, depression, or irritability — similar to stimulant side effects (22).

The Clinical Pharmacogenetics Implementation Consortium (CPIC) is an international group that evaluates scientific evidence and produces practical guidelines for using genetics in medicine, especially for drug dosing and safety. Their recommendations are widely used in pharmacogenomics.

For atomoxetine, CPIC guidance is unusually strong. They recommend not only CYP2D6 genetic testing, but also therapeutic drug monitoring in certain cases. This reflects how unpredictable atomoxetine exposure can be from person to person. Knowing whether someone is a fast or slow metaboliser can help clinicians choose a safer starting dose and decide how quickly to adjust it.

Related Medications:

Other medicines sometimes used for ADHD include:

• Dexamfetamine

• Lisdexamfetamine

• Methylphenidate

• Viloxazine