Guanfacine (Oral)


Guanfacine is a prescription medicine that's used either with other medicines or alone to treat hypertension (high blood pressure). Guanfacine is available as a tablet, as well as an extended-release tablet. The extended release tablet is used for treating symptoms of ADHD in children.

Guanfacine is in a class of medications known as alpha adrenergic agonists. It treats hypertension by relaxing the blood vessels and lowering the heart rate to allow blood to flow more easily all over the body. The extended-release tablets may help treat ADHD in children by affecting the brain section that controls impulsivity and attention.

The standard Guanfacine tablet is normally taken once per day at bedtime. Similarly, the extended-release tablet of Guanfacine is normally taken once per day. Swallow the whole extended-release tablet. Don't break, chew, or crush the tablets.

Guanfacine is only available with a doctor's prescription and comes under the brand names Intuniv and Tenex.

Common Guanfacine side effects include weakness, headache, and dry mouth. Guanfacine may bring on drowsiness. Don't operate heavy machinery or drive a vehicle until you're aware of how it affects you.

Conditions Treated

  • High blood pressure
  • ADHD (attention deficit hyperactivity disorder)

Type Of Medicine

  • Alpha adrenergic agonist

Side Effects

Apart from its useful effects, Guanfacine can bring on some adverse effects. Not all of the effects below may occur, but if they happen they may require medical care.

Check with your physician at once if you experience any of the effects listed below while using Guanfacine:

More common:

  • Confusion
  • Sweating
  • Blurred vision
  • Unusual weakness/tiredness
  • Lightheadedness, faintness, or dizziness when standing up from a lying/sitting position

Less common:

  • Cough
  • Increased urge to urinate
  • Chest discomfort or pain
  • Passing urine more frequently
  • Noisy breathing
  • Difficulty with breathing
  • Irregular, fast, or slow heartbeat
  • Mental depression
  • Pounding heartbeat
  • Tightness in chest
  • Fainting, dizziness, or lightheadedness

Get emergency help at once if any of these overdose symptoms happen while using Guanfacine:

  • Unusual weakness or tiredness (severe)
  • Faintness or dizziness (extreme)

Some Guanfacine side effects can occur that normally don't require medical care. They may disappear during treatment as you get used to Guanfacine. In addition, your healthcare giver may help you find ways to reduce or prevent some of these effects. If you've got any questions about these effects, if they persist or if they're bothersome, be sure to consult your healthcare professional.

More common:

  • Dizziness
  • Drowsiness
  • Constipation
  • Headache
  • Irritability
  • Nausea
  • Dryness of mouth
  • Unusual drowsiness or sleepiness
  • Vomiting
  • Weight gain
  • Upper stomach or abdominal pain
  • Nausea
  • Unusual drowsiness, tiredness, feeling of sluggishness, weakness, or dullness

Less common:

  • Belching
  • Acid/sour stomach
  • Decreased appetite
  • Burning, itching, or dry eyes
  • Heartburn
  • Loss/lack of strength
  • Paleness of skin
  • Decreased sexual ability
  • Indigestion
  • Stomach upset, pain, or discomfort
  • Trouble with sleeping

After you stop taking Guanfacine, it may still bring about some effects that require medical attention. Please check with your physician at once if you develop these side effects:

  • Increased salivation
  • Tenseness or anxiety
  • Nervousness or restlessness
  • Trembling or shaking of the fingers and hands
  • Sweating cramps
  • Sweating

Other effects not mentioned above may also happen in some people. If you develop any other effects, consult your healthcare professional.


Take Guanfacine as instructed by your physician. Your doctor will monitor your heart rate and blood pressure while you take Guanfacine.

Guanfacine standard-release tablets

The recommended range of dose for standard-release Guanfacine tablets is 1-2 milligrams a day. Your doctor can alter your dose. Don't alter your Guanfacine dose without consulting your doctor. Don't stop using these tablets without consulting your doctor.

Guanfacine extended-release tablets

For extended-release tablets, the recommended range of dose is 1-4 milligrams a day. These tablets should be used once a day, either with a stimulant medication for ADHD prescribed by your doctor or alone. Your doctor will direct you when to use Guanfacine, as well as when to use ADHD stimulant medication.

You should swallow Guanfacine extended-release tablets whole with some milk, water or other fluid. Don't open, break, crush or chew extended-release tablets. Simply swallow them whole. If you can't swallow them whole, notify your doctor.

Don't take a high-fat meal with extended-release tablets and don't stop using these tablets without consulting your doctor.

If you're treating ADHD with Intuniv, the best time to take your dose is in the morning. If you're treating hypertension with Tenex, you should take the tablets at bedtime, as Tenex can cause severe drowsiness. Make sure to follow your physician's instructions.

If you notice any changes in the strength, type or brand of Guanfacine you take, your dose may need to change. Always take a look at your refills to ensure you've received the right type and brand of medication prescribed by your physician. If you've got any doubts about the medication you get at your pharmacy, ask the pharmacist.

Your physician will need to monitor your progress as you take Guanfacine. They may also need to check your heart rate and blood pressure.

You shouldn't stop taking Guanfacine suddenly. Stopping this medication suddenly can worsen your condition, possibly causing unpleasant symptoms.

If you're receiving treatment for hypertension, keep using Guanfacine even if you start to feel well. There are often no symptoms when it comes to high blood pressure. You might need to use blood pressure medicine for life.

If you've used excess Guanfacine, seek emergency medical care or call up your nearest poison control center straight away. Symptoms of a Guanfacine overdose may include dizziness, fainting, blurred vision, lack of energy, drowsiness, slow heart rate and smaller pupils (dark circles in the center of the eyes).


Guanfacine may interact with any of these:

  • Alcohol
  • Abiraterone
  • Aliskiren
  • Aldesleukin
  • Amifostine
  • Amiodarone
  • Azelastine
  • Aprepitant
  • Baclofen
  • Azole antifungal agents (Voriconazole, Ketoconazole, Itraconazole)
  • Alpha blockers (Doxazosin, Alfuzosin, Tamsulosin)
  • Alpha agonists (Methyldopa, Clonidine)
  • Amphetamines (Lisdexamphetamine, Dextroamphetamine)
  • Angiotensin receptor blockers (Irbesartan, Candasartan, Losartan)
  • Angiotensin-converting enzyme inhibitors (Ramipril, Lisinopril, Captopril)
  • Antipsychotics (Risperidone, Chlorpromazine, Clozapine, Olanzapine, Haloperidol, Quetiapine)
  • Barbiturates (Phenobarbital, Butalbital)
  • Beta-adrenergic blockers (Sotalol, Propranolol, Atenolol)
  • Benzodiazepines (Lorazepam, Diazepam, Alprazolam)
  • Bosentan
  • Boceprevir
  • Bicalutamide
  • Buprenorphine
  • Brimonidine
  • Buspirone
  • Chloral hydrate
  • Cyclosporine
  • Conivaptan
  • Calcium channel blockers (Verapamil, Nifedipine, Diltiazem, Amlodipine)
  • Galantamine
  • Fingolimod
  • Dronedarone
  • Digoxin
  • Deferasirox
  • Dexamethasone
  • Diazoxide
  • Diuretics/water pills (Triamterene, Furosemide, Hydrochlorothiazide)
  • Lomitapide
  • Levodopa
  • Mononitrate, Dinitrate, Isosorbide
  • Grapefruit juice
  • General anesthetics (medicines used to put patients to sleep prior to surgery)
  • HIV protease inhibitors (Saquinavir, Ritonavir, Indinavir, Atazanavir)
  • HIV non-nucleoside reverse transcriptase inhibitors (Nevirapine, Etravirine, Delavirdine, Efavirenz)
  • Methyphenidate
  • Macrolide antibiotics (Erythromycin, Clarithromycin)
  • Mirtazapine
  • Metyrosine
  • Metronidazole
  • Mitotane
  • Mifepristone
  • Modafinil
  • Muscle relaxants (Orphenadrine, Cyclobenzaprine, Methocarbamol)
  • Monoamine oxidase inhibitors (Tranylcypromine, Selegiline, Rasagiline, Phenelzine, Moclobemide)
  • Narcotic pain relievers (Oxycodone, Morphine, Fentanyl, Codeine)
  • Nitrates (Isosorbide Mononitrate, Isosorbide Dinitrate, Nitroglycerin)
  • Nabilone
  • Nefazodone
  • Norfloxacin
  • Olopatadine
  • Octreotide
  • Phosphodiesterase 5 inhibitors (Vardenafil, Tadalafil, Sildenafil)
  • Pentoxifylline
  • Pasireotide
  • Perampanel
  • Primidone
  • Pramipexole
  • Rivastigmine
  • Rufinamide
  • Ropinirole
  • Rituximab
  • Rifampin
  • Rifabutin
  • Scopolamine
  • St John's Wort
  • Simeprevir
  • Sodium Oxybate (GBH)
  • Zopiclone
  • Zolpidem
  • Tramadol
  • Thalidomide
  • Tizanidine
  • Thalidomide
  • Tapentadol
  • Tetracycline
  • Tocilizumab

Seizure medications (Clobazam, Carbamazepine, Phenobarbital, Phenytoin, Levetiracetam, Valproic Acid, Primidone, Topiramate)

Selective serotonin reuptake inhibitors (Sertraline, Paroxetine, Fluoxetine, Citalopram)

Serotonin-norepinephrine reuptake inhibitors (Venlafaxine, Duloxetine, Desvenlafaxine)

Tyrosine kinase inhibitors (Imatinib, Dabrafenib, Crizotinib)

Tricyclic antidepressants (Trimipramine, Clomipramine, Desipramine, Amitriptyline)

If you're using any of the medicines above, consult your pharmacist and doctor. When two medications interact, it doesn't mean you must stop using one of them. Find out from your doctor how any interactions should be handled or how they're being handled.

Medicines other than the above can interact with Guanfacine. Tell your pharmacist and doctor about all kinds of medication you're using, including over the counter, prescription and herbal medications. Also report any supplements you're taking.


Before using Guanfacine, tell your pharmacist and doctor about your medical past, especially if you have liver disease, kidney disease, blood pressure problems (both high and low), fainting, heart disease (e.g slow heart rate) or a family or personal history of mood or mental disorders (e.g depression, suicidal thoughts, bipolar disorder).

Decreased kidney function or kidney disease may cause Guanfacine to accumulate in the body, potentially causing some side effects. If you or your child have kidney disease or reduced kidney function, discuss with your healthcare professional how Guanfacine can affect their condition, how their condition can affect the efficacy and dosing of Guanfacine, and whether you or your child require any special monitoring.

Decreased liver function or liver disease can cause Guanfacine to accumulate in the body, possibly causing some side effects. If you or your child have liver disease or decreased liver function, discuss with your healthcare professional how Guanfacine can affect their condition, how their condition can affect the efficacy and dosing of Guanfacine, and whether you or your child require any special monitoring.

Tell your pharmacist and physician if you have allergies to Guanfacine, any of Guanfacine's ingredients or any other medicines. Get the list of Guanfacine ingredients from your pharmacist.

You need to know that Guanfacine standard-release tablets and extended-release tablets have Guanfacine as the active ingredient. Please don't take these two products at once.

Tell your pharmacist and doctor what other medications (prescription and non-prescription), nutritional supplements and vitamins you plan to take or are taking. Make sure to name any of these: antidepressants, antihistamines, barbiturates, like Phenobarbital (Luminal), Clarithromycin (in PrevPac, Biaxin), Carbamazepine (Tegretol, Equetro, Epitol, Carbatrol), Itraconazole (Sporanox, Onmel), Indinavir (Crixivan), medications for seizures, nausea, mental illness, high blood pressure or anxiety, Phenytoin (Phenytex, Dilantin), Nelfinavir (Viracept), Nefazodone, Pioglitazone (in Oseni, in Duetact, in Actoplus Met, Actos), Rifampin (Rimactane, in Rifater, in Rifamate, Rifadin), Rifabutin (Mycobutin), Ritonavir (in Kaletra, Norvir), sleeping pills, sedatives, Valproic Acid (Depakene) and tranquilizers. Your healthcare professional may need to alter your doses of medications or carefully check on you for side effects.

Inform your healthcare professional what herbal medications you're using, particularly St John's Wort.

Tell your healthcare professional if you've fainted before or if you've suffered a heart attack recently, if you've had a stroke before or have it now, or if you've had the following conditions: low blood pressure, bipolar disorder (a condition that causes spells of mania, depression and other unusual moods), slow heart rate, or liver, kidney or heart disease.

Tell your physician if you plan to get pregnant or are pregnant. Also, tell them if you're nursing a young child. If you become pregnant while using Guanfacine, call your doctor.

If you're having an operation, including a dental operation, tell your dentist or doctor that you're using Guanfacine.

You need to know that Guanfacine can make you dizzy or drowsy. Don't operate machines or drive a car until you understand how Guanfacine affects you.

Ask your physician about the safe intake of alcoholic drinks while you're using Guanfacine. Alcohol may worsen Guanfacine side effects.

Guanfacine may worsen the effect of CNS depressants (medicines that make you less alert, or drowsy). CNS depressants include antihistamines or medication for hay fever, colds or other allergies, sedatives, sleeping medicines or tranquilizers, narcotics or prescription pain medicine, barbiturates or medicine for seizures, anesthetics or muscle relaxants. Check with your physician before using any of the medications above while you/your child is using Guanfacine.

Guanfacine can cause fainting, lightheadedness and dizziness when you stand up too fast from a lying/sitting position. This is quite common when you starting using Guanfacine for the first time. To avoid this problem, slowly get out of your bed and rest your feet for a couple of minutes on the floor before standing up.

You might faint if you get overheated or dehydrated during your Guanfacine treatment. Make sure to take lots of fluids and stay in a cool place while taking Guanfacine.

You should use Guanfacine as part of a comprehensive treatment plan for ADHD, which can include special education and counselling. Be sure to follow your therapist's and doctor's instructions.

Your doctor should monitor you or your child's progress regularly to ensure that this medication is working well and to determine if you/your child should continue to use it.

Your doctor will also need to check you or your child's heart rate and blood pressure before starting to use Guanfacine and while either of you is taking it. If you detect any change in you or your child's recommended heart rate or blood pressure, contact your doctor promptly. If you've got any questions about this, consult your doctor.

Don't suddenly stop using Guanfacine without consulting your doctor first. Stopping Guanfacine suddenly may raise your heart rate and blood pressure (rebound hypertension). Before you stop using this medicine completely, your physician may tell you to gradually decrease the dose you or your child is taking.

Be sure to have adequate Guanfacine readily available to last through your holidays, vacations and weekends. You shouldn't skip any doses. You should ask your physician for an extra written Guanfacine prescription to keep in your purse or wallet. You then can have it completed if your medicine runs out when you're away from home.

This medicine may make heart rhythm problems worse (such as atrioventricular block, sinus node dysfunction), especially in patients using other medications. If you've got any concerns, speak to your physician.

Guanfacine may bring on dryness of the throat, mouth and nose. To temporarily relieve mouth dryness, eat sugarless gum or candy, use a saliva alternative or melt ice bits in your mouth. However, if your dry mouth persists for longer than 14 days, check with your dentist or physician. Persistent dryness of your mouth can increase the risk of dental disorders, including gum disease, tooth decay and fungus infections.

Children may be more vulnerable to Guanfacine side effects, especially mental or mood changes and hallucinations.

Senior citizens may also be more vulnerable to Guanfacine side effects, especially dizziness (particularly when standing up), depression, slow heartbeat or drowsiness. Drowsiness and dizziness may raise your risk of falling.

Please consult your doctor about drinking grapefruit juice and eating grapefruit while you're using Guanfacine. This is because Guanfacine may interact with grapefruit and grapefruit juice, making the medication less effective.


Keep Guanfacine at 20-25 degrees Celsius (room temperature) and make sure it's kept away from high temperature and light. Also, don't keep Guanfacine in damp or moist places, including bathrooms.

Don't keep medicines you no longer need or outdated medicine. Ask your healthcare provider about how to safely discard any medication you don't use, including Guanfacine.

Keep all medicines, including Guanfacine, out of children's reach.


If you're allergic to Guanfacine or any of its ingredients, don't take it.

Before you use Guanfacine, make sure to tell your physician if you've got heart disease, coronary artery disease or heart block, if you've had lower blood pressure, kidney or liver disease or stroke before, or if you've suffered a heart attack recently.

Guanfacine may hinder your reactions and thinking. Therefore, be cautious if you drive a vehicle or carry out any activity that needs you to be attentive.

Avoid becoming dehydrated or overheated in hot weather or during exercise. Also, avoid taking alcohol while using this medication.

To ensure that Guanfacine is helping treat your medical condition and not bringing on adverse effects, your healthcare professional will need to track your progress regularly. They may need to check your heart rate and blood pressure, as well. Make sure to honor all of your follow-up appointments with your doctor.

If you're receiving treatment for hypertension (high blood pressure), keep using Guanfacine even if you begin to feel fine. Often, hypertension doesn't have symptoms. You may have to take blood pressure medicine for life.

Tell your physician if you use other medications that make you drowsy on a regular basis. They can worsen the sleepiness brought on by Guanfacine. Ask your healthcare provider before using Guanfacine with a narcotic pain medicine, sleeping pills, muscle relaxer or medication for seizures, anxiety and depression.

You shouldn't suddenly stop using Guanfacine. Doing so can worsen your medical condition and you could develop unpleasant symptoms.

Guanfacine is not thought to harm an unborn child. Please tell your physician if you plan to get pregnant or are pregnant while receiving Guanfacine.

It is not clear whether Guanfacine gets into human milk. It's also unclear whether it might harm a nursing infant. Please talk to your physician if you're nursing a baby.

Follow all instructions found on the package and medicine label. Report all your medical problems, allergies, as well as any medications you use to your healthcare professional.

Guanfacine can also be taken for other conditions not discussed in this medicine guide. For more details about this medication, please consult your pharmacist and doctor.