Alpha-2 Adrenoceptor Agonist (ADHD / Opioid Withdrawal / Tic Disorders) Pregnancy: Caution — clonidine crosses placenta; neonatal bradycardia and hypotension reported. Short-term use may be acceptable for opioid withdrawal management in pregnancy under specialist supervision. Discuss risks/benefits with obstetrician and addiction specialist.

Clonidine

Brand names: Catapres, Dixarit

Adult dose

Dose: ADHD (off-label): 50–150 micrograms two to three times daily. Opioid withdrawal (adjunct): 75–150 micrograms three times daily. Menopausal flushing: 50–75 micrograms twice daily (Dixarit). Hypertension: 0.1–0.3 mg twice daily

Route: Oral

Frequency: Two to three times daily

Max: 900 micrograms/day (hypertension); 400 micrograms/day (ADHD off-label — lower doses preferred)

Multiple psychiatric indications — all off-label in psychiatry except tic disorders (limited licence). ADHD: used as alternative to guanfacine (older agent; more sedation and hypotension; twice-daily dosing). Opioid withdrawal: reduces autonomic symptoms (sweating, diarrhoea, tachycardia, hypertension) but does NOT reduce craving or psychological withdrawal. Tic disorder: 25–100 micrograms three times daily. Source: BNF 90; NICE NG87.

Paediatric dose

Dose: ADHD/tics: 2–6 micrograms/kg/day in divided doses (max 300 micrograms/day children 6–12 years). Start 25 micrograms at night micrograms/day/kg

Route: Oral

Frequency: Two to three times daily

Max: 300 micrograms/day (children)

Off-label use in paediatric ADHD and Tourette syndrome. In children, clonidine is second-line to guanfacine (better-tolerated, once-daily dosing, licensed). Useful for ADHD+tics combination. Source: BNF for Children 2024.

Dose adjustments

Renal

Severe renal impairment: reduce dose by 50% and monitor carefully — renal excretion is major route of elimination (40–60% unchanged in urine). eGFR <30 mL/min: start at lowest dose and titrate slowly.

Hepatic

No dose adjustment required.

Paediatric weight-based calculator

Patient weight (kg)

Clinical pearls

Opioid withdrawal — mechanism and limitations: clonidine reduces autonomic opioid withdrawal symptoms (sweating, diarrhoea, tachycardia, piloerection, hypertension) by suppressing noradrenergic activity in the locus coeruleus. It does NOT address craving, mood dysregulation, or insomnia effectively. Use as adjunct to buprenorphine/methadone OST or bridge during naltrexone induction. Lofexidine (Lucemyra) is a more selective alpha-2 agonist licensed specifically for opioid withdrawal in UK with less hypotension.
ADHD use vs guanfacine: clonidine (non-selective alpha-1 and alpha-2 agonist) vs guanfacine (selective alpha-2A). Clonidine has stronger sedative properties, more hypotension, twice-daily dosing requirement, and less specific PFC effect. Guanfacine (Intuniv) is now preferred as first-line non-stimulant ADHD drug. Clonidine is useful when sedation is desirable (ADHD + severe insomnia, ADHD + anxiety) or when guanfacine is not tolerated/available.
Rebound hypertension — the critical withdrawal warning: clonidine must NEVER be abruptly discontinued in patients on doses >300 micrograms/day. Abrupt withdrawal → rebound catecholamine surge → hypertensive crisis with BP potentially exceeding 200/120 mmHg within 12–24 hours. Always taper over minimum 1 week (longer for higher doses). Risk is highest if on concurrent beta-blocker — beta-blockade without alpha-blockade worsens the hypertensive rebound.
Tic disorders — clonidine for Tourette syndrome: NICE NG88 (Tourette syndrome) includes clonidine as a pharmacological option for tic reduction, particularly where ADHD comorbidity exists. Reduces tic severity by approximately 30–40% in controlled studies. Effect on tics may take 4–6 weeks to emerge. Guanfacine preferred for tics + ADHD combination.
Menopausal flushing — Dixarit: 50 micrograms twice daily (licensed indication). Reduces flushing frequency but less effective than HRT. Used in patients where HRT is contraindicated (breast cancer, oestrogen-sensitive malignancy). Reduced efficacy vs HRT in most studies. Source: BNF 90; BNF for Children 2024; NICE NG87; NICE NG88 (Tourette syndrome).

Contraindications

Sick sinus syndrome or AV block (bradycardia risk — alpha-2 agonism reduces SA node automaticity)
Severe coronary artery disease (risk of rebound hypertension on discontinuation)
Hypotension at baseline

Side effects

Sedation and fatigue (most common — useful for sleep problems in ADHD, but limits daytime use)
Dry mouth (alpha-2 agonism reduces salivary secretion)
Hypotension and bradycardia (alpha-2 central and peripheral effects)
Rebound hypertension on abrupt withdrawal (adrenergic rebound — taper over 1–2 weeks; MHRA warning for antihypertensive use)
Depression (alpha-2 agonism reduces norepinephrine tone — can worsen depressive symptoms in susceptible patients)
Constipation, erectile dysfunction

Interactions

Beta-blockers: additive bradycardia; rebound hypertension on clonidine withdrawal is worsened — taper clonidine before stopping beta-blocker (paradoxical hypertensive crisis if clonidine stopped abruptly while on non-selective beta-blocker)
Tricyclic antidepressants (amitriptyline, imipramine): reduce clonidine antihypertensive effect by antagonising alpha-2 receptors — avoid combination or close BP monitoring
Antihypertensives: additive hypotension
CNS depressants (alcohol, benzodiazepines): additive sedation
Methylphenidate/amphetamines: clonidine used to counteract stimulant-related insomnia and tics — small risk of cardiac arrhythmia with combination (case reports); monitor ECG

Monitoring

Blood pressure and pulse at baseline, 2 weeks after dose change, then monthly (hypotension and bradycardia)
ADHD symptom scores or tic severity (YGTSS) at 4–6 weeks and 3 months
Sleep quality (sedation benefit in ADHD insomnia)
Mood (depression monitoring — clonidine can worsen mood via norepinephrine suppression)
Renal function (severe CKD — dose adjustment required)
Withdrawal monitoring if tapering (BP monitoring during taper)

Reference: BNFc; BNF 90; BNF for Children 2024; NICE NG87 (ADHD); NICE NG88 (Tourette syndrome); UK Drug Misuse and Dependence Guidelines 2017 (opioid withdrawal). Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways