Tenex Side Effects

Generic Name: guanfacine

Note: This document contains side effect information about guanfacine. Some of the dosage forms listed on this page may not apply to the brand name Tenex.

Some side effects of Tenex may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to guanfacine: oral tablet, oral tablet extended release

Along with its needed effects, guanfacine (the active ingredient contained in Tenex) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking guanfacine:

More common
  • Blurred vision
  • confusion
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • sweating
  • unusual tiredness or weakness
Less common
  • Chest pain or discomfort
  • cough
  • difficulty with breathing
  • fast, slow, or irregular heartbeat
  • increased need to urinate
  • lightheadedness, dizziness, or fainting
  • mental depression
  • noisy breathing
  • passing urine more often
  • pounding heartbeat
  • tightness in the chest

Get emergency help immediately if any of the following symptoms of overdose occur while taking guanfacine:

Symptoms of overdose
  • Dizziness (extreme) or faintness
  • unusual tiredness or weakness (severe)

Some side effects of guanfacine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Constipation
  • dizziness
  • drowsiness
  • dryness of the mouth
  • headache
  • irritability
  • nausea
  • sleepiness or unusual drowsiness
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • upper abdominal or stomach pain
  • vomiting
  • weight gain
Less common
  • Acid or sour stomach
  • belching
  • decreased appetite
  • decreased sexual ability
  • dry, itching, or burning eyes
  • heartburn
  • indigestion
  • lack or loss of strength
  • paleness of the skin
  • stomach discomfort, upset, or pain
  • trouble with sleeping

After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, check with your doctor immediately if you notice the following side effects:

  • Anxiety or tenseness
  • increased salivation
  • nervousness or restlessness
  • shaking or trembling of the hands and fingers
  • stomach cramps
  • sweating

For Healthcare Professionals

Applies to guanfacine: oral tablet, oral tablet extended release

General

Guanfacine (the active ingredient contained in Tenex) is generally well-tolerated. In a study of 580 hypertensive patients, only 7% withdrew due to adverse side effects. In addition, most side effects were mild, dose-related, and resolved over time.

Nervous system

Nervous system side effects have included fatigue or a sedative effect and dizziness in 33% and 15% of patients, respectively. After one year of therapy, the incidence of these side effects falls to 6% and 1%, respectively. Headaches occur in less than 5% of patients. Nervous system side effects associated with the extended-release formulation have included somnolence (38%), fatigue (14%), headache (24%), lethargy (6%), dizziness (6%), and postural dizziness (less than 2%).

Gastrointestinal

Gastrointestinal side effects have included dry mouth in up to 60% of patients. Constipation has been associated with the use of this drug in 14% of patients. After one year of therapy the incidence of dry mouth and constipation averages 15% and 3%, respectively. Gastrointestinal side effects associated with the extended-release formulation have included dry mouth (4%), upper abdominal pain (10%), nausea (6%), and dyspepsia (less than 2%).

Cardiovascular

Cardiovascular side effects have included orthostatic hypotension and palpitations, each of which is rare. There is limited, indirect (ECG) evidence of left ventricular hypertrophy resolution after guanfacine (the active ingredient contained in Tenex) therapy. Cardiovascular side effects associated with the extended-release formulation have included hypotension/decreased blood pressure (6%), atrioventricular block (less than 2%), bradycardia (less than 2%), and sinus arrhythmia (less than 2%) .

Genitourinary

Genitourinary complaints in male patients are limited to impotence, which is associated with higher doses (daily doses of 3 mg or more).

Metabolic

Metabolic side effects associated with the extended-release formulation have included decreased appetite (5%), and constipation (3%).

Psychiatric

Psychiatric side effects associated with the extended-release formulation have included irritability (6%)

Postmarketing reports: Hallucinations

Respiratory

Respiratory side effects associated with the extended-release formulation have included asthma (less than 2%).

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

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