Name: Tenex

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Symptoms of overdose may include:

  • drowsiness
  • lack of energy
  • slow heart rate
  • fainting
  • dizziness
  • blurred vision
  • smaller pupils (black circles in the middle of the eyes)

What else should I know about guanfacine-oral?

What preparations of guanfacine-oral are available?
  • Intuniv: Extended-Release Tablets: 1, 2, 3, and 4 mg
  • Tenex: Immediate-Release Tablets: 1 and 2 mg

How should I keep guanfacine-oral stored?

Tablets should be stored at room temperature, between 15 C to 30 C (59 F to 86 F).

Adverse Effects


Xerostomia (10-60%)

Somnolence (5-39%)

Headache (0.2-26%)

Dizziness (2-15%)

Constipation (2-16%)

Fatigue (2-15%)

Abdominal pain (11%)


Hypotension (7%)

Asthenia (2-7%)

Impotence (0-7%)

Lethargy (6%)

Dizziness (6%)

Irritability (6%)

Nausea (3-6%)

Decreased appetite (5%)

Weakness (1-5%)

Insomnia (3-4%)

Bradycardia (3%)

Palpitations (3%)

Confusion (3%)

Depression (3%)

Dyspnea (3%)

Alopecia (3%)

Dermatitis (3%)

Diaphoresis (3%)

Pruritus (3%)

Dyspepsia (3%)

Dysphagia (3%)

Hypokinesia (3%)

Leg cramps (3%)

Frequency Not Defined

Orthostatic hypotension





Postmarketing Reports

Cardiovascular: Bradycardia, palpitations, syncope, tachycardia

CNS: Paresthesias, vertigo

GI: Abdominal pain, constipation, diarrhea, dyspepsia

Liver/biliary: Abnormal LFTs

Musculoskeletal: Arthralgia, leg cramps, leg pain, myalgia

Psychiatric: Agitation, anxiety, confusion, depression, hallucinations, insomnia, nervousness

Reproductive: Impotence

Respiratory: Dyspnea

Skin: Alopecia, dermatitis, exfoliative dermatitis, pruritus, rash

Sensory: Blurred vision, alterations in taste

Urinary: Nocturia, urinary frequency

Other: Asthenia, chest pain, edema, malaise, tremor

Tenex Overview

Tenex is a prescription medication used alone or with other medications to treat high blood pressure. 

Tenex belongs to a group of drugs called centrally acting alpha 2A -adrenergic receptor agonists. Tenex treats high blood pressure by decreasing heart rate and relaxing the blood vessels so that blood can flow more easily through the body.&

Tenex comes as a tablet and is usually taken once daily at bedtime.

Common side effects include dry mouth, weakness and headache. Tenex can cause drowsiness. Do not drive or operate heavy machinery until you know how this medication affects you.

Tenex Usage

  • Take Tenex exactly as your doctor tells you. 
  • Your doctor may change your dose. Do not change your dose of Tenex without talking to your doctor. 
  • Do not stop taking Tenex without talking to your doctor. 
  • Your doctor will check your blood pressure and heart rate while you take Tenex. 
  • If you take too much Tenex, call your local Poison Control Center or go to the nearest emergency room right away.

Tenex Dosage

Take Tenex exactly as prescribed by your doctor. Follow the directions on your prescription label carefully. Your doctor will determine the best dose for you.

The recommended dose range of Tenex is 1 mg to 2 mg per day. 


How should I take Tenex (guanfacine)?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

If you take Intuniv to treat ADHD, take your dose in the morning.

If you take Tenex to treat hypertension, you may need to take your dose at bedtime if guanfacine causes severe drowsiness. Follow your doctor's instructions.

Do not crush, chew, break, or open an Intuniv extended-release tablet. Swallow it whole.

If there are any changes in the brand, strength, or type of guanfacine you use, your dosage needs may change. Always check your refills to make sure you have received the correct brand and type of medicine prescribed by your doctor. Ask the pharmacist if you have any questions about the medicine you receive at the pharmacy.

Your doctor will need to check your progress while you are using guanfacine. Your blood pressure and heart rate may also need to be checked.

You should not stop using guanfacine suddenly. Stopping suddenly may make your condition worse, and you could have unpleasant symptoms.

If you are being treated for high blood pressure, keep using this medication even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medication for the rest of your life.

Store at room temperature away from moisture, heat, and light.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include severe drowsiness, slow heart rate, and feeling like you might pass out.

Tenex Dosage and Administration



  • Adjust dosage carefully according to patient's BP response and tolerance.1 2

  • Carefully monitor BP during initial titration or subsequent upward adjustment in dosage.500 501

  • Goal is to achieve and maintain optimal control of BP; individualize specific target BP based on a consideration of multiple factors, including patient age and comorbidities, and currently available evidence from clinical studies.500 501

Attention Deficit Hyperactivity Disorder

  • Monitor BP, especially during initial dosage adjustment;9 some experts also recommend ECG monitoring.10


Oral Administration

Minimize adverse effects (e.g., somnolence) by administering guanfacine initially at bedtime.1


Available as guanfacine hydrochloride; dosage expressed in terms of guanfacine.1

Pediatric Patients

Hypertension Oral

Children ≥12 years of age: Initially, 1 mg daily.1

If a satisfactory response is not obtained after 3–4 weeks of therapy, may increase dosage to 2 mg once daily at bedtime, although most of the antihypertensive effect is observed at a dosage of 1 mg daily.1 5

Although higher dosages (i.e., >2 mg daily) have been used, dosages >3 mg daily were associated with a substantially increased incidence of adverse effects.1 2

Attention Deficit Hyperactivity Disorder† Oral

Children 7–14 years of age: Initially, 0.5 mg daily (given as a single dose at bedtime) has been administered.9

Dosage has been increased with caution over 2–4 weeks (e.g., by 0.5 mg every 4 days) to a maximum of 4 mg daily in 3 divided doses.9


Hypertension Oral

Initially, 1 mg daily.1

If a satisfactory response is not obtained after 3–4 weeks of therapy, may increase dosage to 2 mg once daily at bedtime, although most of the antihypertensive effect is observed at a dosage of 1 mg daily.1 5

Although higher dosages (i.e., >2 mg daily) have been used, dosages >3 mg daily were associated with a substantially increased incidence of adverse effects.1 2

Some experts recommend usual dosage range of 0.5–2 mg once daily.500

Prescribing Limits

Pediatric Patients

Hypertension Oral

Children ≥12 years of age: Dosages >3 mg daily were associated with a substantially increased incidence of adverse effects.1 2 5

Attention Deficit Hyperactivity Disorder† Oral

Children 7–14 years of age: Maximum 4 mg daily.9 10 16


Hypertension Oral

Dosages >3 mg daily were associated with a substantially increased incidence of adverse effects.1 2 5

Special Populations

Hepatic Impairment

No specific dosage recommendations at this time.1

Renal Impairment

Administer dosages at the low end of the dosing range in patients with renal impairment.1 16

May administer usual doses (possibly at low end of dosing range) in patients undergoing dialysis, because limited amounts of the drug are removed by dialysis.1

Geriatric Patients

Select dosage with caution (usually starting at the low end of the dosing range) because of age-related decreases in hepatic, renal, and/or cardiac function and concomitant disease and drug therapy.1





Tight, light-resistant containers at 15–30°C.1

Commonly used brand name(s)

In the U.S.

  • Intuniv
  • Tenex

Available Dosage Forms:

  • Tablet
  • Tablet, Extended Release

Therapeutic Class: Antihypertensive

Pharmacologic Class: Alpha-2 Adrenergic Agonist

Precautions While Using Tenex

Your doctor should check you or your child's progress at regular visits to make sure this medicine is working properly and to decide if you or your child should continue to take it.

You or your child will also need to have your blood pressure and heart rate measured before starting this medicine and while you or your child are using it. If you notice any change to you or your child's recommended blood pressure or heart rate, call your doctor right away. If you have questions about this, talk to your doctor.

Do not stop taking this medicine without checking first with your doctor. Your doctor may want you to gradually reduce the amount you or your child are taking before stopping it completely.

Make sure that you have enough guanfacine on hand to last through weekends, holidays, and vacations. You should not miss any doses. You may want to ask your doctor for another written prescription for guanfacine to carry in your wallet or purse. You can then have it filled if you run out when you are away from home.

Before having any kind of surgery (including dental surgery) or emergency treatment, tell the medical doctor or dentist in charge that you are using this medicine.

Guanfacine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds, sedatives, tranquilizers, or sleeping medicine, prescription pain medicine or narcotics, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you or your child are using this medicine.

Guanfacine may cause some people to become dizzy, drowsy, faint, lightheaded, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert. Also, standing up slowly when getting up from a lying or sitting position may also help.

Guanfacine may cause dryness of the mouth, nose, and throat. For temporary relief of mouth dryness, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if dry mouth continues for more than 2 weeks, check with your physician or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.

What do I need to tell my doctor BEFORE I take Tenex?

  • If you have an allergy to guanfacine or any other part of Tenex (guanfacine tablets).
  • If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
  • If you are taking another drug that has the same drug in it.

This is not a list of all drugs or health problems that interact with this medicine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take Tenex with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

Information for Patients

Patients who receive Tenex should be advised to exercise caution when operating dangerous machinery or driving motor vehicles until it is determined that they do not become drowsy or dizzy from the medication. Patients should be warned that their tolerance for alcohol and other CNS depressants may be diminished. Patients should be advised not to discontinue therapy abruptly.

Drug Abuse and Dependence

No reported abuse or dependence has been associated with the administration of Tenex (guanfacine hdyrochloride).