Centrally-acting α2-agonist Pregnancy: Limited data; use in pregnancy only if considered essential, with careful monitoring of mother and child. Clonidine crosses the placenta and may lower fetal heart rate; a transient rise in newborn blood pressure post-partum cannot be excluded. Oral forms preferred; IV injection should be avoided. Not recommended during breastfeeding (excreted in human milk).

Clonidine hydrochloride

Brand names: Catapres, Dixarit

Clonidine hydrochloride is a centrally acting antihypertensive, also used in some settings for resistant hypertension and certain off-licence indications such as menopausal flushing.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 50–100 micrograms three times daily initially, increased gradually to a usual maintenance of 300–1200 micrograms daily in divided doses

Route: Oral

Frequency: three times daily initially (divided daily doses)

Oral treatment (hypertension) should commence with 50–100 micrograms three times daily, increased gradually every second or third day until control is achieved. Most patients are controlled on divided daily doses of 300–1200 micrograms; some may require higher doses, e.g. 1800 micrograms or more. May be added to an existing antihypertensive regimen. Patients undergoing anaesthesia should continue clonidine before, during and after anaesthesia using oral or IV administration according to circumstances. Do not withdraw abruptly (risk of rebound hypertension) — reduce the dose gradually; if given with a beta-blocker, do not discontinue clonidine until several days after the beta-blocker has been withdrawn.

Dose adjustments

Renal

Dosage must be adjusted to the individual antihypertensive response, which can be highly variable in renal insufficiency; careful monitoring required. Only a minimal amount is removed by routine haemodialysis, so no supplemental dose is needed after dialysis.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known hypersensitivity to the active ingredient or other components of the product
Severe bradyarrhythmia resulting from sick sinus syndrome or 2nd or 3rd degree AV block
Rare hereditary conditions that may be incompatible with an excipient of the product

Side effects

Dry mouth
Sedation, dizziness, headache
Orthostatic hypotension
Constipation, nausea, vomiting
Depression and sleep disorder; erectile dysfunction; fatigue

Interactions

Beta-blockers — if given concurrently, clonidine should not be discontinued until several days after the beta-blocker is withdrawn (rebound hypertension risk); withdrawal symptoms may be treated with alpha- and beta-adrenoceptor blocking agents

Clinical monograph

How it works

It stimulates central alpha-2 adrenoceptors, reducing sympathetic outflow from the brain to lower peripheral vascular resistance, heart rate and blood pressure.

Prescribing in practice

Do not stop abruptly, as sudden withdrawal can cause a dangerous rebound hypertensive crisis, so always taper the dose.
Sedation, dry mouth and a slow heart rate are common, and it should be used cautiously with other sedating or rate-limiting drugs.
Use caution in bradyarrhythmias and significant cerebrovascular or cardiovascular disease.

Monitoring

Monitor blood pressure and heart rate, with particular vigilance for rebound hypertension if treatment is interrupted.

Counselling the patient

Never stop this medicine suddenly; reductions must be gradual and supervised.
It may cause drowsiness and a dry mouth, so take care with driving until you know how it affects you.
Report fainting, a very slow pulse or a sudden rise in blood pressure if a dose is missed.

Evidence & guidelines

The rebound hypertension risk on abrupt withdrawal of centrally acting alpha-2 agonists is well established, and clonidine remains a recognised option for resistant hypertension in current prescribing references.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Pathways