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Guanfacine XR (Intuniv XR®)

Guanfacine (Intuniv XR®) belongs to a group of medications called “alpha2 agonists”.

What is this medication used for?

Health Canada has approved guanfacine extended-release (XR) for use in children and adolescents age 6 years and older. Guanfacine can help improve symptoms of attention-deficit/ hyperactivity disorder (ADHD), including difficulties paying attention, impulsive behaviour and hyperactivity.

It may also help treat tic disorders, symptoms of disruptive behaviour disorders, irritability of autism and post-traumatic stress disorder (PTSD). When potential benefits outweigh risks, guanfacine may be prescribed “off-label.” Learn more about off-label medication use:

Tell your doctor or pharmacist if you:

  • Have allergies or bad reactions to a medication
  • Take (or plan to take) other prescription or non- prescription medications, including natural medicines. Some medications interact with guanfacine. Your doctor may adjust medication doses or monitor for side effects
  • Have a history (or family history) of kidney or liver disease, seizures, fainting or bipolar disorder
  • Have a history (or family history) of heart disease, heart block, arrhythmia or “familial long QT syndrome”
  • Miss a period, are pregnant, breast-feeding or planning a pregnancy
  • Use alcohol or drugs. Taking guanfacine together with certain substances may cause a bad reaction. Learn more at

When will the medication start to work?

You (or your family members) may notice some improvements in symptoms of ADHD after 2 weeks. However, other effects such as drowsiness may appear sooner (or immediately). It may take several weeks for full beneficial effects.

It is important that you continue taking guanfacine regularly even if you are feeling well, as it can prevent symptoms from returning. Talk with your doctor if you feel guanfacine treatment has not been helpful. Your doctor may recommend switching you to a different medication.

This medication is not addictive. Do not stop taking it before talking to your doctor.

How do I take this medication?

Guanfacine XR is usually taken once daily, at the same time each day. You may take guanfacine with or without food, but avoid taking it with high-fat meals. Usually, you will start with a low dose and slowly increase this dose over several weeks, based on how you tolerate it.

Guanfacine XR tablets should be swallowed whole with fluid. They should not be divided, crushed, chewed or placed in water. Avoid eating grapefruit or drinking grapefruit juice while taking guanfacine as this may lead to increased blood levels and side effects.

Possible common or serious side effects:

Side effects may be more common when starting a medication or after a dose increase. Talk to your doctor, nurse or pharmacist if any side effect concerns you.

  • Drowsiness or fatigue
  • Dizziness, lightheadedness or headache
  • Low blood pressure or heart rate
  • Dry mouth or constipation
  • Nausea or stomach ache
  • Changes in appetite or weight gain

Contact your doctor immediately if you experience:

  • Thoughts of hurting yourself, hostility or suicide
  • Changes in mood to an unusual state of depression, excitement, irritability or happiness
  • Seeing, hearing or feeling things that are not there
  • Increased or worsened aggression, hostility or depression
  • Fast or irregular heart beat
  • Chest pain or shortness of breath
  • Unexpected rash or seizure

What precautions should my doctor and I be aware of when taking this medication?

  • While taking guanfacine, if you feel dizzy, drowsy or slowed down, do not drive a car or operate heavy machinery. Alcohol could make this worse. Try to avoid alcohol while taking guanfacine.
  • While taking guanfacine, avoid becoming dehydrated or overheated. Drink enough fluids and avoid doing a lot of physical activity on hot days.
  • It is important not to stop taking guanfacine abruptly. Stopping suddenly is associated with “rebound hypertension” that involves a rapid increase in blood pressure and heart rate to levels above normal. This may cause agitation, headache, stomach upset, sweating, nausea or vomiting. If these occur, seek immediate medical attention.

What special instructions should I follow while using this medication?

  • Keep all your appointments with your doctor and the lab.
  • Your doctor may order physical exams, or assessments such as ADHD rating scales and reports from your teachers, before or after starting guanfacine. This is to make sure it is working well for you and monitor for side effects.
  • Do not allow anyone else to use your medication.

What should I do if I forget to take a dose of this medication?

If you forget to take a dose of guanfacine, take the missed dose as soon as you remember. However, if it is more than 4 hours after your scheduled dose, skip the missed dose and continue with your regular schedule. DO NOT double your next dose to try to ‘catch up’.

If you miss 2 or more doses of guanfacine, contact your doctor. You may have to restart the medication at the lowest available dose and slowly increase the dose upwards.

How do I store this medication?

Keep this medication in the original container, stored at room temperature away from moisture and heat and protected from light. Keep this medication out of reach and sight of children.

How does this medication work?

Guanfacine works by affecting the activity of the brain chemical norepinephrine, which influences blood pressure, heart rate and anxiety in the body. Reducing norepinephrine activity also stabilizes areas of the brain affecting impulsive actions, attention and body movements, making them less excitable and improving symptoms of ADHD, tic disorders and disruptive behaviour disorders.

How well does the medication work in children and adolescents?

Evidence supports the use of guanfacine in children and adolescents with ADHD. Guanfacine is commonly used (alone or in addition to stimulants) when stimulants have not been effective or well-tolerated. Limited evidence suggests that guanfacine may also be effective for treatment of PTSD and management of impulsive behaviour or hyperactivity problems associated with tic disorders and irritability associated with autism in children and adolescents. Whenever possible, the addition of behavioural management strategies (such as rewarding good behaviour and teaching problem-solving techniques) can increase the potential for benefit.

How long should I take the medication for?

This depends on the symptoms you have, how frequently they occur, and how long you have had them. Different people take guanfacine for different lengths of time. From time to time, your doctor should evaluate whether you need ongoing treatment with this medication. Some people only require it during particular times of their life such as when they are in school. Other people benefit from ongoing treatment for many years.

Do not increase, decrease, or stop taking this medication without discussing it with your doctor. If you stop taking guanfacine suddenly, it is possible that your symptoms may return or you may have a bad reaction.

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