Medication Information Leaflet

What is this medication for?

Atomoxetine is used to treat attention deficit hyperactivity disorder (ADHD).  It works by increasing the amount of a brain chemical substance called noradrenaline to increase attention, concentration and reduce impulsive and hyperactive behaviour.

How should I take/use this medication?

  • Do not stop taking your medication without checking with your healthcare professional.
  • You may take this medication with or without food.
  • Do not crush, chew or open up the capsules as the contents may irritate the eye. If the contents of the capsule come into contact with the eye, flush it immediately with water and seek medical advice. Wash your hands and any potentially contaminated surface as soon as possible. 
  • Your doctor would start the medication at a low dose, and then slowly adjust the dose according to your response. It will take a few weeks for the medication to work properly, so you may not see much difference in your symptoms in the beginning. It is important that you continue to give the medication as you have been told by your doctor. The improvement in symptoms may also vary from person to person. 

What should I do if I forget to take this medication?

If you forget to take a dose, take it as soon as you remember (but do not take more than your total daily dose prescribed in any 24 hours). Then take your next dose at the usual time. Do not take two doses to make up for the missed dose.  

What precautions should I take?

Inform your healthcare professional if: 
  • You are allergic to this medication or any of the other ingredients of this medication
  • You are pregnant, planning to become pregnant, or breastfeeding
  • You are taking any other medications, including supplements, traditional medications and herbal remedies currently or in the last two weeks.
  • You have a history of or current medical conditions such as blood vessel disease, high blood pressure, stroke, heart disease, pheochromocytoma (tumour in the adrenal glands), mental health conditions, glaucoma, overactive thyroid, liver disease, seizures (fits), hard-to-control or repeated twitching of any parts of the body or you repeat sounds and  words (Tourette’s syndrome or tics disorder)

In some cases, particularly in young people below the age of 25 years, this medication may cause the following changes to a person’s mental condition, especially in the first few weeks of treatment or during dose changes:
  • New or worsening thoughts of harming yourself or ending your life
  • Worsening agitation, restlessness, violent behaviour, or
  • Other changes in mood or behaviour
Please inform your doctor as soon as possible, or for your family or caregiver to inform your doctor if you are unable to seek treatment on your own.

Do not stop taking this medication on your own without discussing with your doctor.

It is important to note that your doctor has prescribed this medication as he/she feels you will benefit more from taking this medication over the possible risks that it may cause, which have a low chance of occurring, and most people take this medication without any of such problems.

What are some common side-effects of this medication?

This  include:
  • Stomach discomfort e.g. stomach pain, nausea, vomiting
    • Take it after food to minimise these side effects. 
  • Dry mouth
  • Constipation 
  • Decreased appetite and weight loss
  • Excessive sweating 
  • Headache, difficulty in sleeping or drowsiness
  • Decrease in sexual drive or ability 
Most of these side effects will get better or go away as your body gets used to the medication. 
Inform your doctor if the side effects above become severe and bothersome.

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 
  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body
Very rarely, this medication may cause:
  • Fast or irregular heartbeat (palpitations)
  • Very high blood pressure 
    • Signs and symptoms may include severe headache or dizziness, fainting or change in eyesight
  • Liver problems
    • Signs and symptoms may include dark urine, feeling tired, loss of appetite, upset stomach or stomach pain, throwing up, light-coloured stools, yellow skin or eyes.
  • Prolonged and/or painful erections (for males) lasting up to 4 hours or beyond
  • Trouble passing urine
  • New or worsening mental symptoms such as delusions (false beliefs), hallucinations (seeing or hearing things that are not real) or mania (abnormally high or excited mood)

What food or medication should I avoid when I take this medication?

Some medications might interact with atomoxetine. Check with your doctor or pharmacist if you want to take/give any other medications, supplements or herbal products. 

If you see another doctor, inform him that you are taking this medication before he prescribes any other medications.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight at room temperature. Keep this medication away from children. 

How should I throw away this medication safely?

Pack this medication into a trash bag and seal it tightly before throwing into the rubbish chute or bin.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on July 2022

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