Atomoxetine

About atomoxetine

Please note

This page will give you general information about atomoxetine. It is not medical advice.

Always talk to your doctor about your situation and whether this medication is for you.

Thinking about trying medication? Read our guide

How atomoxetine works

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.

Atomoxetine and everyday life

Frequently asked questions

You may not get the full benefit of taking atomoxetine for four to six weeks.

Some young people have experienced growth delay in weight and height when they start to take atomoxetine. This has been linked to having a lower appetite – a side effect of the medicine. Over time, most of these young people have caught up with their peers.

Make sure that you get your height and weight checked before you start taking atomoxetine, and at regular intervals while you are taking it.

Sometimes the doctor might stop the medicine or change the dose for a while to let you catch up on weight and height, and then start it again.

Talk to your doctor about this if it is a problem for you.

You may want to let your family and friends know you are taking atomoxetine so they can support you and help you look out for side effects.

For guidance on this, check out our page on getting support with your medication.

Atomoxetine can make you feel tired and sleepy.

It has also made some people find it difficult to get to sleep and stay asleep. Some people also wake up early in the morning and are unable to get back to sleep.

Talk to your doctor about this if it is a problem for you.

Alcohol

You can continue to drink alcohol while taking atomoxetine but having the two together might make you very sleepy.

During the first few days, it might be best to stop drinking alcohol until you see how the medicine affects you.

Street drugs

We do not have any information about using atomoxetine with drugs as not enough research has been carried out.

Atomoxetine is not a central nervous system stimulant, but it does affect the balance of chemicals in the brain.

There may be some reactions if you mix it with drugs, which could be dangerous, but we do not know what they are.

If you are taking other medicines, atomoxetine may affect how well they work or may cause side effects. Tell your doctor about these before you start your treatment.

Talk to your pharmacist if you buy any medications over the counter to treat common illnesses like colds and flu, or topical applications that you put on your skin.

You should not take atomoxetine if you have taken a medicine known as a monoamine oxidase inhibitor (MAOI) antidepressant like phenelzine, isocarboxazid, tranylcypromine or moclobemide in the last two weeks.

Atomoxetine capsules 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.

Check with your pharmacist if you’re concerned about any of atomoxetine’s ingredients.

Do not drive a car or ride a bike just after you start taking atomoxetine.

Taking atomoxetine may make you feel tired or dizzy when you first start treatment.

This could affect you if you drive a car, ride a bike, or do anything else that needs a lot of focus. It might be best to stop doing these things for the first few days, until you know how it affects you.

Do not worry - most people do these things as normal while taking atomoxetine.

Pregnancy

We do not have enough information to know whether it is dangerous or not to take atomoxetine during pregnancy.

You should use a good method of contraception while taking this medication.

Talk to your doctor if you are trying to get pregnant or become pregnant while taking atomoxetine. Together, you can decide whether to continue this medication or find a suitable alternative.

Breastfeeding

We know that atomoxetine passes into breastmilk, but the exact amounts are not clear.

We do not know for certain that it is not harmful to the baby.

You should discuss feeding options with your doctor or midwife.

Sex

Atomoxetine can have side effects that may affect your sex life, these include:

pain in the penis and/or testicles or an erection that is painful and lasts for a long time (priapism) - if this happens to you, visit a hospital or see your doctor immediately as this can be dangerous
feeling too tired to have sex

These effects should pass after the first couple of weeks. If they don’t, and this is a problem for you, go back to your doctor to discuss your options.

If it works for you, atomoxetine may have a positive effect on your sex life as your symptoms settle, and you can concentrate on your relationships.

Fertility

We do not have enough information to know if there are effects on fertility, but it is thought to be unlikely.

Atomoxetine is not a banned substance in sport.

You may feel tired or dizzy at first, however, which may cause a problem in sports where you need a lot of focus.

It might be best to stop doing those sports for a short time until you know how the medicine affects you.

Do not worry - most people play sports as normal while taking atomoxetine.

Try not to take atomoxetine for the first time just before your exams, as you may feel tired or dizzy when you start taking it.

You should talk to your doctor about any future exams if you are starting atomoxetine. You might decide together to delay starting it until you have done them. If they are more than a month away, however, you might find that it is better to start atomoxetine to improve your motivation to study.

Do not worry - most people take exams as normal while taking atomoxetine.

Your doctor should know

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.

Uses, warnings, safety and side effects of atomoxetine

Taking atomoxetine

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 should I do if I miss a dose of atomoxetine?

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.

Warnings and safety

Safety headlines

If you have taken more atomoxetine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately - even if you do not feel any different.

Atomoxetine can make some people think about hurting themselves or taking their own lives. You must go straight to hospital with your medicine if you have any of these thoughts.

Atomoxetine may cause other rare but serious side effects: allergic reactions (difficulty breathing, swelling of your face or throat, itching skin lumps), priapism (a painful erection that lasts a long time), and other serious symptoms that you can find here. Go to a hospital if you get any of these symptoms, taking your medicine with you.

Do not take atomoxetine if you have taken a monoamine oxidase inhibitor antidepressant (MAOI) like moclobemide, phenelzine, isocarboxazid or tranylcypromine in the last 14 days.

Do not drive a car, ride a bike or operate machinery until you see how atomoxetine affects you, as it could make you sleepy at first.

We do not know how safe it is to take atomoxetine during pregnancy. Use good contraception while you are taking atomoxetine. If you become pregnant while taking atomoxetine, continue taking your medication but see your doctor as soon as possible.

Atomoxetine can affect how the liver works. If you have stomach pains, feel sick or generally unwell, lose your appetite or notice your skin or eyes start to look yellow, then see your doctor straight away.

When to go to the hospital

If you have taken more atomoxetine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately – even if you do not feel any different. Go to A&E with your medication and tell doctors how much you have taken. Get a friend or family member to go with you, in case you feel ill on the way.

You might get any of the following signs:

upset stomach and gut
sleepiness
dizziness
shaking
unusual behaviour

See your doctor or go to a hospital straight away if you get any of the following side effects from taking atomoxetine:

feeling or having a very fast heartbeat, or an uneven heartbeat
feeling aggressive, angry or hostile
having mood swings or mood changes
swelling of the face and throat, difficulty breathing, hives (small raised itchy patches of skin)
seizures (fits)
psychotic symptoms including hallucinations (hearing voices or seeing things which are not there), believing things that are not true, or being extra suspicious.
having a priapism (a painful and long-lasting erection)

If any of the symptoms start suddenly and get bad very quickly (such as trouble breathing) you (or a friend) should call 999 and ask for an ambulance.

While taking atomoxetine some people may think about hurting themselves or taking their own lives. This can happen to anyone, including people who are under 18. You must go straight to hospital with your medicine if you have any of these thoughts. You must tell the doctor that you are taking atomoxetine.

When to see your doctor

Atomoxetine can sometimes cause problems with your liver. This side effect is rare but serious, so it is important that you know about it and what to do if you think it is a problem for you.

Please tell your doctor before you start taking atomoxetine if you have ever had liver problems – they may give you a lower dose.

Look out for any of these signs that may mean your liver is not working as well as it could do and go to a doctor straight away if you get any of them:

pain in your stomach or gut which is sore if you press it on the right side, just under your ribs
feeling sick for no obvious reason
generally feeling unwell – feeling tired, or like you are getting flu
itching
your wee is darker in colour than usual
jaundice (your skin or the whites of your eyes start to look a bit yellow)

Monitoring

Before you begin treatment, your doctor should check your blood pressure and your pulse (heart rate).

They should also make a note of your weight and height.

Your doctor should also check your blood pressure and pulse (heart rate) if your dose of medication is changed and at least every six months for as long as you take atomoxetine.

They will also check your weight and height at least every six months but may do this more often if you have concerns about these areas.

Side effects of atomoxetine

The most common side effects of atomoxetine should get better after a few days. If they do not, or they get worse, you should go back to your doctor.

If you get any side effects not listed here please look at the patient leaflet in the medicine pack.

Young people and children are more likely to experience mood swings, changes in mood and feeling like hurting themselves or taking their own lives when taking atomoxetine. If this happens to you, go to the hospital immediately, taking your medication with you. If possible, take a friend or family member along with you to keep you safe on the way.

Very common side effects of atomoxetine, affecting more than one in ten people, include:

stomach or gut pain/feeling or being sick
loss of appetite
faster pulse rate

Common side effects of atomoxetine, affecting up to one in ten people include:

feeling irritable, agitated, restless, anxious, sad or hopeless
depression (low mood)
problems getting to sleep, staying asleep or waking up early
twitching that you cannot control
the pupil (dark centre) of the eye getting larger
indigestion
constipation (not being able to poo)
feeling dizzy
a rash or itchy skin
feeling tired or lacking in energy
weight loss
chest pain