How it works
What does atomoxetine do?
Atomoxetine is a noradrenaline reuptake inhibitor.
Atomoxetine is not a central nervous stimulant, which makes it different from other treatments for attention deficit hyperactivity disorder (ADHD). Instead, it makes more noradrenaline available in your brain.
We are still not sure exactly how atomoxetine works – but this is what we know so far:
- One of the chemicals in the brain is called noradrenaline (also known as norepinephrine). This transmitter is released from nerve endings to carry messages from one nerve cell to another in the brain.
- After sending the message, noradrenaline is taken back up by the nerve endings in a recycling process. Atomoxetine is a molecule that stops this process. This means that the levels of active noradrenaline in the brain increase.
- Higher levels of noradrenaline in the brain help to make people more alert and ready for action. They feel like they have increased wellbeing and more energy.
- It should help to increase your attention span and your concentration, and stop you acting on impulse without thinking.
- Outside of the brain higher levels of noradrenaline have other effects in different parts of the body, including the heart, the gut and the lungs. This can lead to unwanted side effects. It is hard to predict if and how you will be affected as each person is different.
How long does atomoxetine take to start working?
You may not get the full benefit of taking atomoxetine for four to six weeks.
How long will I need to take atomoxetine?
You and your doctor should talk about how long you need to take atomoxetine before you start your treatment.
If you take atomoxetine for ADHD and find it helpful, your doctor will probably recommend that you take it for at least six months to one year.
Atomoxetine does not cure ADHD but helps to treat the symptoms. If you stop this medicine, your old symptoms can come back.
Atomoxetine does not need to be taken forever. It is important that your doctor reviews your treatment with you at least once every year to see if you still need it.
You and your doctor might discuss taking a break from the medication to see how this affects you. This can be done during holidays from school, college or university, so that it doesn’t disrupt your studies.
Your doctor needs to know if...
You need to talk to your doctor or pharmacist before starting treatment with atomoxetine if any of the following apply to you:
- if you know you are, or think you could be, allergic to any of the ingredients (a list of ingredients can be found in the patient information leaflet that comes with your medication)
- you have ever had thoughts about taking your own life or have tried to take your own life in the past
- you have ever had problems with your heart (including heart defects) or an increased heartbeat
- you have high or low blood pressure
- you or a family member has a history of heart disease or stroke
- you have ever had liver problems
- you have ever had psychotic symptoms including hallucinations (hearing voices or seeing things which are not there), believing things that are not true, or being extra suspicious
- you have ever had mania (feeling elated or over-excited, causing unusual behaviour and agitation)
- you have ever had aggressive, unfriendly or unusually angry feelings
- you have a history of epilepsy or have had seizures (fits) for any other reason
- you have ever had extreme mood swings
- you have ever had repeated twitching of any parts of the body that you cannot control, or you repeat sounds and words
- you have an eye disease called narrow-angle glaucoma (increased pressure in your eye)
- you have a tumour of your adrenal gland (phaeochromocytoma)
Tell your doctor or pharmacist if you are taking any other medicines.
If you are already taking a central nervous system stimulant like methylphenidate, your doctor will usually advise you to overlap this with atomoxetine for a few weeks as you switch treatments. This lets the atomoxetine build up in your system and have the chance to start working before you stop the stimulant.
How can atomoxetine be taken?
You can take atomoxetine as capsules. These contain gelatin.
You can also take atomoxetine as a liquid. The oral solution contains sorbitol and anyone with hereditary fructose intolerance should not take this. It also contains sucralose, but this should not affect your blood sugars if you are diabetic.
You should only take atomoxetine as agreed with your doctor.
You may have to take atomoxetine once or twice a day.
Make sure that you know your dose. If it's not written on the label, check with your pharmacist or doctor.
Take one dose in the morning at breakfast time. If you need to take this medicine twice a day, you can take another dose in the later afternoon or early evening. If you take it later in the evening, you might find it harder to get to sleep.
Swallow the capsule with some water, without chewing it. It does not matter if you take it before or after food.
Do not open the capsule to take out the powder as it can irritate your eyes. If you accidentally split a capsule, you should wash your hands thoroughly. If the powder does get into your eyes, wash them out with water and see a doctor as soon as possible.
What if I miss a dose?
If you forget to take a dose, then just take it as soon as possible, unless it is getting close to your next dose.
If you forget to take it by the evening, just start again the next day.
If you usually take a dose in the afternoon or evening as well, just take the next dose when it is due.
Do not take a double dose.
What will happen if I forget to take my atomoxetine?
If you forget to take to take your medicine for a few days, your symptoms may come back.
Stopping the use of atomoxetine
Once you start taking atomoxetine, the brain adjusts to having a new level of noradrenaline around.
If you stop taking atomoxetine all at once, the balance starts to change again.
There are no reported withdrawal effects if you stop atomoxetine suddenly, but you could get your old symptoms back.
If you do not want to take this medicine anymore, it is important that you talk to your doctor about this.
The information on this page was reviewed by the College of Mental Health Pharmacy in March 2020.