HeadMeds gives young people in the United Kingdom general information about medication. HeadMeds does not give you medical advice. Please talk to your Doctor or anyone else who is supporting you about your own situation because everyone is different. Please read more important details about our site.

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Return to Atomoxetine overview
  1. Use and Action
  2. Warnings and side effects
  3. Sex, drink, weight and everything else
Treating adhd add playicon listing
Taking Medikinet to treat ADHD
It makes me feel slower and helps me focus with my work

It has also been used to treat behaviour problems in autism spectrum disorder (ASD).

Atomoxetine can help to adjust the chemicals your brain needs, and focus your energy

  • Atomoxetine is not a stimulant, which makes it different from the other medicines used to treat ADHD. 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 in to the nerve ending in a re-cycling way to stop it working. Atomoxetine is a molecule that stops this recycling. 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 more energy and wellbeing.
  • It should help to increase your attention span, and your concentration, and stop you acting on impulse without thinking. This is the good effects of having more active noradrenaline in the brain
  • 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 leads to many unwanted effects (side effects).
  • It is hard to predict how much effect happens where. Each person is different.

You might have to take atomoxetine once or twice a day

Make sure that you know your dose (how many capsules to take and how many times a day you need to take it). This information should be written on the label of your medicine box. If it is not, check it with your pharmacist or doctor.

  • You might be taking the capsules once or twice a day
  • Take one dose in the morning, at breakfast time
  • Swallow the capsule with some water, without chewing it
  • It does not matter if you take it before or after food
  • 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
  • Do not open the capsule to take out the powder - the powder can irritate your eyes
  • If you accidentally split a capsule, wash your hands and do not rub your eyes

If you get the powder in your eyes, wash them out and see a doctor – take your capsules with you

If you forget to take a dose then just take it as soon as possible unless it is getting close to your next dose

What to do if you miss a dose:

  • If you remember later during the morning, take it as soon as possible.
  • If you forget to take it by the evening, just start again on 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 to make up for any doses you may have missed

What might happen?

  • If you forget to take it for a few days, your symptoms may come back. 

You must go to A&E if you take too much 

What to do if you take too much:

  • If you have taken more atomoxetine than it said on the label, you must get help quickly – even if you do not feel any different.
  • Go to A&E. Take your medicine with you, to show to the doctors. Tell them how much you have taken.
  • Get a friend or family member to go with you, if you can, just 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

It can take 4-6 weeks for atomoxetine to start helping your symptoms

  • It takes 4-6 weeks for atomoxetine to shows its full effects
  • If you are already taking a CNS stimulant like methylphenidate, your doctor will usually advise you to overlap them 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
  • If you don’t know - or cannot remember - how you should take your medicine, or how long to continue the stimulant after starting atomoxetine- always ask your doctor.

Many people take atomoxetine for some months, or even years

You and your doctor should talk about how long you need to take atomoxetine.

  • You will not get the full effect for 4-6 weeks
  • If you take atomoxetine for ADHD and find it helpful, your doctor will probably recommend that you take it for at least 6 months to 1 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
  • They may try a break from the medicine – this will probably be in a holiday (if you are at school or college or University)

Tell your doctor or pharmacist before you take atomoxetine if you have any of these conditions

You need to talk to your doctor or pharmacist 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 killing yourself or trying to kill yourself
  • 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), or believing things that are not true or being extra suspicious.
  • You have ever had mania (feeling elated or over-excited, which causes unusual behaviour) and agitation
  • You have ever had aggressive, unfriendly or unusual angry feelings
  • You have a history of epilepsy or have had fits (seizures) for any other reason
  • You have ever had extreme mood swings or feel very unhappy.
  • You have ever had hard-to-control, repeated twitching of any parts of the body 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)

If you have any thoughts of suicide, or of other ways of hurting yourself, go straight to a hospital with your tablets.

This may be a side-effect, and you need urgent help.

Whilst taking atomoxetine some people may think about hurting themselves or committing suicide. This can happen to anyone, including people who are under 18.

You must go straight to hospital with your tablets if you have any of these thoughts. You must tell the doctor that you are taking atomoxetine. There are other things you can take instead.

Atomoxetine has some side effects, and in some cases they can be serious

See your own doctor or go to a hospital straight away if you get any of the following symptoms:

  • feeling or having a very fast heartbeat, or an uneven heartbeat
  • thinking about or feeling like killing yourself
  • feeling aggressive, unfriendly or very angry
  • having mood swings or mood changes
  • having a serious allergic reaction with symptoms of
  • swelling of the face and throat, difficulty breathing and hives (small raised itchy patches of skin)
  • fits (seizures)
  • psychotic symptoms including hallucinations (hearing voices or seeing things which are not there), or believing things that are not true, or being extra suspicious
  • in men, having a painful and long-lasting erection (priapism)

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

Atomoxetine can sometimes cause problems with your liver – how might this side-effect look

  • 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
  • Your doctor might suggest that you should have blood tests regularly to check how your liver is working
  • Look out for any of these side-effects that might mean your liver is not working as well as it could do – 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
  • The whites of your eyes or skin start to look a bit yellow (jaundice)

Some side-effects that do appear 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

Some side-effects of atomoxetine may – strangely - seem like symptoms of other mental health conditions. Some side-effects here are also the opposites of each other (for example, it might cause sleepiness or trouble getting to sleep). The balance of chemicals in the brain is very fragile, and hard to control. If they do not get better after a few days on the tablets, go back to the doctor. 

Young people were more likely than adults to get some side-effects in tests

Young people and children were more likely than adults to get the following side-effects:

  • Mood swings or changes in mood
  • Feeling like hurting or killing themselves

Atomoxetine does not mix well with some other medicines and drugs

Do not take atomoxetine if you take any of the following:

  • If you took a medicine known as a monoamine oxidase inhibitor (MAOI) like phenelzine, isocarboxazid, tranylcypromine or moclobemide in the last two weeks.

Other medicines may not mix well with atomoxetine. Tell your doctor or pharmacist if you are taking any other medicines.

If you buy medicines (including things you put on your skin) for common illnesses, it is always best to get these from a pharmacy (and not a supermarket or a general store). Always tell the pharmacist you are taking atomoxetine so they can make sure that anything they sell you is safe to take with this medicine.

Get your heart and growth checked regularly when you are taking atomoxetine

  • Before you begin treatment, the doctor should check your blood pressure and your heart rate (pulse)
  • They should also make a note of your weight and height
  • Your doctor should check your blood pressure and heart rate (pulse) if your dose of medication is changed and at least every 6 months for as long as you take atomoxetine
  • They will also check your weight and height at least every 6 months, but may do this more often

Stopping the medication causes the balance of chemicals in the brain to alter

  • 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. It is not a good idea to suddenly stop taking your medicine without talking to your doctor. 

Some side-effects that do appear should get better after a few days. If they do not, you should go back to your doctor.

Don't stop taking Atomoxetine until you talk to your doctor or you may get withdrawal symptoms as well.

Very common - could affect more than 1 in 10 people

  • Headache
  • Sleepiness
  • Stomach or gut pain, feeling or being sick
  • Not feeling hungry
  • Faster pulse
  • Dry mouth
  • Common - could affect up to 1 in 10 people

    • Feeling irritable, agitated, restless, anxious, sad or hopeless
    • Having a low mood (depression)
    • Problems getting to sleep, staying asleep, and waking early
    • Twitching that you cannot control
    • The pupil (dark centre) of your eye getting larger
    • An upset stomach, indigestion or constipation
    • Feeling dizzy
    • A rash or swollen, red and itchy skin
    • Feeling tired or lazy
    • Losing weight
    • Having chest pain
    • Uncommon - likely to affect up to 1 in every 100 people

      • There are other side-effects that you can get when taking this medicine – we have only included the most common ones here. Please look at the leaflet inside your medicine box, or ask a doctor or pharmacist, if you want to know if you are getting a side-effect from your medicine. If you do get a side-effect, please think about reporting it via the Yellow Card scheme.