Information About Guanfacine HCl, Sold As Tenex, Estulic or Dipresan

Are you taking, or considering taking, Guanfacine (Tenex) for ADHD, social phobia, or another mental health reason? This page provides information on the medication’s benefits, side effects, and other properties.

Type of Medication: Antihypertensive and Norepinephrine Regulator

Guanfacine (Tenex) was originally developed as, and is still used as, a mild antihypertensive. Like some other antihypertensive drugs, Guanfacine (Tenex) regulates levels of the neurotransmitter norepinephrine; in the prefrontal cortex of the brain, it decreases sensitivity to distracting stimuli, and it therefore may help with focus. For this reason, it can be helpful in reducing ADHD symptoms, either alone or in combination with stimulants.

Guanfacine hydrochloride is sold in the United States and Canada as Tenex, and as Dipresan or Estulic in several other countries.

Benefits of Guanfacine (Tenex) for ADHD and Social Phobia

While stimulants are still considered the first line of drug treatment for ADHD, they increase levels of norepinephrine nonspecifically throughout the brain; in the prefrontal cortext, this may help reduce distractibility, but at the expense of undesirable side effects in other areas of the brain that may lead to nervousness, insomnia, decreased appetite, irritability, muscle twitches, stomach ache, or hypertension. Guanfacine (Tenex) therefore offers an alternative drug treatment for ADHD for the roughly 30% of children who cannot tolerate stimulants.

Guanfacine (Tenex) is also sometimes used in the treatment of tic disorders and social phobias, or social anxiety disorder.

Side Effects of Guanfacine (Tenex)

Please note that the following side effects include only some of the most common and somewhat less common but do not include rarer side effects; the list is not exhaustive. Many people taking Guanfacine (Tenex) experience none of these side effects. Please consult a physician about any unusual symptoms.


Some of the more common side effects of Guanfacine (Tenex) include:

  • drowsiness
  • headache
  • dizziness
  • xerostomia (dry mouth)
  • constipation
  • asthenia (weakness)

Less Common

Some of the less common side effects of Guanfacine (Tenex) include:

  • fatigue
  • impotence

Note that mania and aggressive behavior have been reported in pediatric patients with ADHD who received Guanfacine. All such patients had medical or family risk factors for bipolar disorder, and all patients recovered upon discontinuation of guanfacine HCl.

Guanfacine (Tenex) and Alcohol

Alcohol should be avoided: patients taking Guanfacine (Tenex) may find that their tolerance for alcohol and other central nervous system depressants is diminished.

Stopping Guanfacine (Tenex): Discontinuation Effects or Withdrawal Symptoms

Abrupt discontinuation of Guanfacine HCl can result in nervousness, anxiety and rarely, rebound hypertension (the latter typically occurring 2-4 days after withdrawal).

Should You Buy Guanfacine (Tenex) Online?

Particularly in the United States, many individuals choose to purchase medications online, either for reasons of cost savings, privacy, or both. Both brand-name Tenex and so-called ‘generic Tenex’ (i.e., Guanfacine without the Tenex brand name) can sometimes be purchased at deep discounts (and sometimes without a prescription) in this way. Before undertaking any purchase of medications online, however — and certainly if you are contemplating doing so without a prior prescription — please consider the integrity of the supplier and the national and/or local laws which may apply where you live.

Information Sources and Disclaimer

The information provided here has been summarized in good faith purely for educational purposes. It is not intended in any way to replace the advice of a qualified medical professional. Please do not take any action on the basis of information contained here without consulting a physician. Unless otherwise specified, information is intended to apply only to adult use of the medication. Drug interaction precautions have not been included; please consult another source for this information.

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