Clonidine (Catapres)

  • Generic name: Clonidine
  • Brand names: Catapres, Catapres-TTS, Clorpres, Duraclon, Kapvay
  • Therapeutic class: Antihypertensive, Alpha2-Adrenergic Agonist

What is Clonidine prescribed for?

  • Hypertension
  • Attention-deficit/hyperactivity disorder (ADHD)
  • Alcohol withdrawal, opiate withdrawal
  • Insomnia, including insomnia in children
  • Smoking cessation
  • Relief of menopausal symptoms
  • Anxiety
  • Diabetic diarrhea

Onset of action: blood pressure declines within 30 to 60 minutes after an oral dose, the maximum decrease occurs within 3-5 hours.

Half-life: ranges from 12 to 16 hour. The half-life may increase up to 41 hours in patients with severe impairment of renal function.

Mechanism of action: Clonidine stimulates alpha-adrenergic receptors in the CNS, which results in decreased sympathetic outflow and decreased heart rate and blood pressure, vasoconstriction, and renal vascular resistance. It prevents pain signal transmission to the CNS by stimulating alpha-adrenergic receptors in the spinal cord.

Withdrawal syndrome

Abrupt withdrawal may induce potentially fatal hypertensive crisis. Sudden discontinuation of clonidine produces a rapid increase in diastolic and, especially, systolic blood pressure, increased heart rate, tremor, nervousness, agitation, confusion, restlessness, sweating, palpitation.

Discontinuation of therapy: Taper off oral dose gradually over 2-4 days to avoid withdrawal symptoms.

Clonidine substitutes

Closely related drugs:

  • Methyldopa (Aldomet) is similar to clonidine except that it stimulates both alpha-1 and alpha-2 receptors to lower blood pressure.
  • Guanfacine (Tenex) is another alpha-adrenergic receptor agonist and may be used as an alternative to clonidine for the same indications. Guanfacine appears to cause less sedation and contribute to the less severe withdrawal symptoms than clonidine. Guanfacine is the most close substitute for clonidine.
  • Guanabenz (Wytensin) is the most selective agonist for alpha2-adrenergic receptors.

Entirely different drugs:

  • Lofexidine, baclofen, and buprenorphine suitable alternatives to clonidine in the management of opiate detoxification3.
  • Chlordiazepoxide - for alcohol withdrawal.
  • Moxonidine, atenolol, are labetalol are alternatives in the treatment of high blood pressure. Moxonidine is less likely to cause rebound hypertension than clonidine.
  • Ginkgo biloba is a herbal alternative for ADD/ADHD 3.


  • 1. Clonidine Monograph Reference guide from the American Society of Health-System Pharmacists.
  • 2. Nigam AK, Ray R, Tripathi BM. Buprenorphine in opiate withdrawal: a comparison with clonidine. J Subst Abuse Treat. 1993 Jul-Aug;10(4):391-4.
  • 3. Niederhofer H. Ginkgo biloba treating patients with attention-deficit disorder. Phytother Res. 2010 Jan;24(1):26-7.

Last updated: February, 2015

Good to know


  • Guanfacine (Tenex) has the same pharmacologic mechanism as clonidine, but is better tolerated.
  • Dexmedetomidine is a synthetic analog of clonidine with a number of superiorities.
  • Clonidine acutely stimulates growth hormone release in both children and adults, but does not produce a chronic elevation of growth hormone with long-term use.