Clonidine
2 medicines
Clonidine is a central alpha-2 agonist used to lower blood pressure and to ease opioid withdrawal and ADHD symptoms. Stopping it suddenly can trigger a dangerous rebound rise in blood pressure, so it must always be tapered off gradually.
Key facts
- Clonidine acts on the brain's blood-pressure control centre. It is used to lower high blood pressure that has not responded to other drugs, and at different doses to ease opioid withdrawal symptoms and to help ADHD.
- Its blood-pressure-lowering effect appears within an hour or two of a dose and peaks a few hours later.
- Stopping clonidine suddenly after regular use can cause rebound hypertension, a rapid and sometimes dangerous rise in blood pressure with headache, agitation and a racing heart. It must always be tapered down gradually, never stopped abruptly.
- Seek urgent care for fainting, a very slow heartbeat, or a severe headache with sweating and agitation after a missed dose.
What clonidine treats
Clonidine treats high blood pressure that has not responded well to first-line drugs, eases the cravings and physical discomfort of opioid withdrawal, and helps with attention-deficit hyperactivity disorder (ADHD). It is also used for certain nerve pain and, in some cases, for severe menopausal hot flushes.
How clonidine works
Clonidine stimulates alpha-2 receptors in the brainstem, which dampens the nervous system signals that normally tighten blood vessels and speed the heart. Blood pressure and pulse fall as a result, and the same calming effect on nervous system signals eases opioid withdrawal symptoms and helps steady attention in ADHD.
Before you take it
- Tell your prescriber if you already have low blood pressure, a slow heart rate or heart block, or a history of depression.
- Mention any kidney impairment, since the drug stays in the body longer and effects can be stronger.
- Alcohol, sedatives and other blood-pressure medicines add to drowsiness and low blood pressure.
- Discuss pregnancy and breastfeeding with your prescriber before starting.
Side effects
Common effects include dry mouth, drowsiness, dizziness on standing, constipation, and fatigue.
Stop and seek urgent medical care for any of these:
- A very slow heartbeat or fainting.
- Chest pain.
- Severe headache, agitation or a racing heart after a missed dose.
- Signs of a severe allergic reaction, such as swelling or difficulty breathing.
Safety essentials
- Take every dose on schedule. If treatment needs to stop, your prescriber will taper the dose down over days, because sudden withdrawal can cause a dangerous spike in blood pressure.
- Carry extra doses when travelling so you never miss one.
- Avoid combining clonidine with alcohol or other sedating blood-pressure medicines without medical advice, since the drop in blood pressure and drowsiness can add up.
This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.