Clonidine

Clonidine is a centrally acting alpha-2 adrenergic agonist with multiple clinical applications, including the treatment of hypertension, menopausal hot flushes, migraine prophylaxis, and as an adjunct in the management of attention deficit hyperactivity disorder (ADHD) and opioid withdrawal.

By stimulating alpha-2 adrenoceptors in the brainstem, clonidine reduces sympathetic outflow from the central nervous system.

This lowers peripheral vascular resistance, heart rate, and blood pressure.

The same central mechanism explains its ability to moderate the autonomic symptoms of opioid withdrawal and reduce the frequency of vasomotor flushes in menopause.

Hot Flush Management

For women who cannot or choose not to take hormone replacement therapy, clonidine is one of the few licensed alternatives for menopausal hot flushes.

The evidence for efficacy is more modest than for HRT, but some women find meaningful symptomatic relief.

Hypertension

Clonidine is not a first-line antihypertensive but may be useful as add-on therapy in resistant hypertension or in patients who cannot tolerate standard agents.

How to Take Clonidine

Swallow tablets with water, with or without food. Doses are usually taken two to three times daily. Take at the same times each day for consistent blood levels.

Do Not Stop Suddenly

Abrupt discontinuation of clonidine can cause a dangerous rebound rise in blood pressure (hypertensive crisis), anxiety, agitation, headache, and tremor.

Always taper the dose gradually under medical supervision.

Monitoring

Blood pressure and heart rate should be monitored regularly, especially during dose adjustment. Report dizziness, excessive drowsiness, or dry mouth to your prescriber.

Hypertension

• Starting dose: 50-100 micrograms three times daily
• Increase gradually at weekly intervals
• Usual maintenance: 300-1,200 micrograms daily in divided doses

Menopausal Hot Flushes

• 50-75 micrograms twice daily
• May increase to 75 micrograms three times daily if needed

Migraine Prophylaxis

• 50-75 micrograms twice daily

ADHD (Specialist-Initiated)

• Dosed by body weight; specialist supervision required

Renal Impairment

• Start at the lower end of the dose range and titrate cautiously

Withdrawal

• Taper over at least 2-4 days; longer tapers for high doses

Very Common (affecting more than 1 in 10 patients)

• Drowsiness and sedation
• Dry mouth
• Dizziness

Common (up to 1 in 10 patients)

• Constipation
• Headache
• Nausea
• Fatigue
• Postural hypotension

Uncommon (up to 1 in 100 patients)

• Depression
• Bradycardia
• Raynaud's phenomenon
• Erectile dysfunction
• Sleep disturbance or vivid dreams

Rare (up to 1 in 1,000 patients)

• Atrioventricular block
• Hallucinations
• Gynaecomastia

Very Rare (fewer than 1 in 10,000 patients)

• Severe rebound hypertension on abrupt withdrawal

Drowsiness and dry mouth are the most common early effects and often improve with continued use.

Rebound Hypertension

Never stop clonidine abruptly. Sudden withdrawal, especially from higher doses, can cause a life-threatening hypertensive crisis with headache, palpitations, anxiety, and tremor.

Taper over at least two to four days.

Sedation

Clonidine may significantly impair alertness and reaction times. Avoid driving or operating machinery until you know how it affects you, particularly during dose titration.

Concomitant Beta-Blockers

If withdrawing both clonidine and a beta-blocker, stop the beta-blocker first and then taper clonidine several days later. Concurrent withdrawal increases the risk of rebound hypertension.

Pregnancy

Clonidine crosses the placenta and may cause neonatal hypotension and bradycardia. Use only when the benefit justifies the risk, under specialist supervision.

Do not take clonidine if you have:

• A known hypersensitivity to clonidine or any excipient
• Severe bradyarrhythmia (sick sinus syndrome, second- or third-degree AV block without a pacemaker)

Use with caution in patients with depression, Raynaud's disease, peripheral vascular disease, or a history of rebound hypertension.

Clonidine should not be used as monotherapy in the emergency treatment of hypertensive crises.