Clonidine is a prescription alpha-2 adrenergic agonist that acts centrally in the brainstem to decrease sympathetic outflow. By stimulating alpha-2 receptors, it dampens the nerve signals that tighten blood vessels and accelerate the heart, resulting in lowered systemic vascular resistance, a slower heart rate, and reduced blood pressure. Clinically, clonidine’s unique mechanism makes it useful across several conditions where sympathetic overactivity plays a role.
Primary indications include high blood pressure (hypertension), where clonidine can be used as monotherapy or, more commonly, as an add‑on to other antihypertensives when blood pressure remains above goal. In attention-deficit/hyperactivity disorder (ADHD), extended-release clonidine (e.g., Kapvay) helps reduce hyperactivity, impulsivity, and sleep problems, and is often used alongside stimulant medications or when stimulants are not tolerated. Clonidine is also widely used to alleviate withdrawal symptoms associated with opioids, alcohol, and nicotine by easing autonomic hyperarousal (sweating, agitation, tachycardia), and it may provide relief for menopausal hot flashes by stabilizing thermoregulatory centers.
Formulations include immediate-release tablets, extended-release tablets for ADHD, and transdermal patches (e.g., Catapres-TTS) that deliver clonidine steadily over one week. The transdermal system offers more consistent plasma levels and can improve adherence, especially in patients who prefer once-weekly dosing or who are at risk for rebound hypertension if they miss oral doses. Onset of antihypertensive effect typically occurs within several hours for oral tablets and within 2–3 days for the patch, with full effect by day 3–4.
Beyond its labeled uses, clonidine is sometimes employed off-label for conditions such as anxiety related to PTSD, restless legs syndrome, tic disorders, gastroparesis-related nausea, and certain pain syndromes where sympathetic activity is contributory. Any off-label use should be guided by a clinician who can weigh benefits and risks and monitor side effects and blood pressure changes.
Clonidine dosing is individualized. Start low and titrate cautiously based on clinical response and tolerability. Never stop clonidine abruptly; sudden discontinuation can cause rebound hypertension, headache, palpitations, tremor, anxiety, and, in severe cases, hypertensive crisis.
Renal impairment: Because a portion of clonidine is renally excreted, consider lower starting doses and slower titration in patients with chronic kidney disease. Hepatic impairment: Use caution and titrate slowly. Elderly patients may be more sensitive to hypotension and sedation; conservative dosing is recommended.
Tapering: If clonidine needs to be discontinued, taper gradually over 2–7 days (or longer for higher doses). A common approach is to reduce the total daily dose by 0.1 mg every 2–3 days while monitoring blood pressure and heart rate. If the patient is also taking a beta-blocker, clinicians typically taper the beta-blocker first, then clonidine, to reduce the risk of rebound hypertension.
Administration tips: Take oral doses at the same times each day, with or without food. For the patch, press firmly for 10–15 seconds to ensure proper adhesion and wash hands after application. Avoid placing the patch on irritated, broken, or scarred skin, and avoid applying lotions or oils at the site, which can impair adhesion.
Clonidine can cause dose-related drowsiness, dizziness, dry mouth, and constipation, especially during initiation and dose increases. Use caution with tasks requiring alertness, such as driving or operating machinery. Alcohol and other central nervous system depressants may potentiate sedation and hypotension.
Cardiovascular: Patients with a history of sinus node dysfunction, severe bradycardia, conduction abnormalities (e.g., second- or third-degree AV block), or hypotension should be monitored closely. Clonidine can lower heart rate and blood pressure, and symptomatic hypotension or bradycardia may occur, especially with concomitant medications like beta-blockers, nondihydropyridine calcium channel blockers (verapamil, diltiazem), or digoxin.
Psychiatric: Clonidine may exacerbate depression in some patients and can cause or worsen fatigue and low mood. Monitor for mood changes, especially in individuals with a history of depression or other mental health conditions. Sleep disturbances, vivid dreams, and irritability can also occur during therapy or withdrawal.
Renal disease: Reduced clearance may enhance effects; start low, go slow, and monitor blood pressure, heart rate, and side effects. Dehydration, volume depletion, and excessive heat exposure may amplify hypotensive effects.
Pediatrics and geriatrics: Children and older adults may be more sensitive to sedation and blood pressure changes. In pediatric ADHD, monitor for changes in behavior, sleep patterns, and blood pressure at baseline and during titration. In older adults, orthostatic hypotension can increase the risk of falls—advise slow position changes and adequate hydration unless otherwise restricted.
Pregnancy and lactation: Evidence in pregnancy is limited. Clonidine has been used to treat hypertension during pregnancy, but potential risks and benefits should be weighed on an individual basis. Neonates exposed near delivery may experience hypotension, somnolence, or withdrawal. Clonidine is excreted in breast milk; monitor nursing infants for sedation and poor feeding. Discuss options with a healthcare professional if pregnant, planning pregnancy, or breastfeeding.
Perioperative care: Inform surgeons and anesthesiologists about clonidine use. Abrupt withdrawal before surgery can cause rebound hypertension; many clinicians continue clonidine through the perioperative period and adjust anesthetic plans accordingly.
Do not use clonidine in patients with known hypersensitivity to clonidine or any component of the formulation. Avoid use or employ extreme caution in patients with severe bradycardia, advanced heart block (unless paced), or those at high risk for syncope due to hypotension. Transdermal systems should not be applied to irritated or damaged skin. Withdrawal should be gradual under medical supervision to prevent rebound hypertension.
Most side effects are dose-related and often lessen after the first 1–2 weeks of therapy as the body adapts.
Seek immediate medical attention for chest pain, fainting, severe dizziness, vision changes, difficulty breathing, facial swelling, or signs of stroke (sudden weakness, severe headache, slurred speech).
Practical tips: Sip water or sugar-free lozenges for dry mouth; increase dietary fiber and hydration for constipation; stand up slowly to reduce dizziness; and avoid alcohol and unnecessary sedatives. Report persistent or severe side effects to your clinician—dose adjustments or formulation changes (e.g., switching to the patch) may help.
Clonidine interacts with a range of medications and substances that affect blood pressure, heart rate, and central nervous system activity.
Always provide your healthcare professional with a complete list of prescription drugs, over-the-counter medicines, vitamins, and herbal supplements. If a new medication is added or removed, monitor blood pressure and heart rate as advised.
Oral immediate-release and extended-release tablets: If you miss a dose and it is within a few hours of your usual time, take it as soon as you remember. If it is close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not double up or take extra to make up for a missed dose. Repeated missed doses increase the risk of rebound hypertension—contact your clinician if this occurs.
Transdermal patch: If a patch loosens or falls off, try to reapply it to the same location or replace it with a new patch at a different site and continue the original schedule. If you replace it, note the day you applied the new patch and follow the weekly change interval from that day. Avoid applying tape or coverings that can trap heat, which may increase drug absorption unexpectedly. If multiple patches fall off or adherence is poor, discuss alternative formulations with your clinician.
Symptoms of clonidine overdose can include marked drowsiness, profound hypotension, bradycardia, pinpoint pupils, hypothermia, slowed breathing, weakness, and, in severe cases, loss of consciousness. Paradoxical transient hypertension may occur early due to peripheral alpha stimulation before central effects predominate. Children are particularly sensitive to clonidine toxicity even at relatively low doses.
Suspected overdose is a medical emergency. Call emergency services or poison control immediately. Management typically involves airway support, supplemental oxygen, IV fluids for hypotension, and careful cardiac monitoring. Medications such as atropine for bradycardia or vasopressors for refractory hypotension may be used under medical supervision. Do not attempt to induce vomiting unless instructed by a healthcare professional.
Store clonidine tablets at controlled room temperature (20–25°C / 68–77°F), protected from moisture, heat, and direct sunlight. Keep in the original container with the lid tightly closed. Do not store in the bathroom.
For transdermal patches, keep each patch sealed in its pouch until use. Store flat at room temperature and avoid excessive heat. After removal, fold the patch adhesive sides together before discarding in a secure container out of reach of children and pets. Never flush medications unless labeling specifically instructs you to do so; consult local guidelines for safe disposal.
As with all medicines, keep clonidine out of sight and reach of children and pets. Use child-resistant closures and consider a lockable storage box if there are young children in the home.
In the United States, clonidine is a prescription-only medication regulated by the FDA. It is available as immediate-release tablets, extended-release tablets for ADHD (e.g., Kapvay), and transdermal patches (e.g., Catapres-TTS). A licensed healthcare professional must evaluate appropriateness and issue or authorize the prescription before dispensing. Because clonidine affects blood pressure and heart rate, clinicians typically monitor vitals and clinical response during initiation and dose adjustments, and refills may be limited to support safe follow-up.
Clonidine cannot be legally purchased over the counter in the U.S. without prescriber authorization. Telehealth services may provide evaluation and prescribing where permitted by state law, and mail-order pharmacies can dispense after receipt of a valid prescription. Use for ADHD, substance withdrawal, menopausal hot flashes, or other off-label purposes should be supervised by a clinician who can counsel on dosing, titration, and tapering, and who can coordinate care with other medications that influence heart rate and blood pressure.
HealthSouth Rehabilitation Hospital at MountainView offers a legal and structured solution for acquiring clonidine without a formal patient-carried paper prescription by using clinician-led protocols and standing orders in accordance with applicable laws and regulations. Under this model, patients undergo appropriate screening and evaluation by licensed providers, and medications are dispensed or arranged through compliant channels with built-in monitoring and follow-up. Availability may vary by state and program; identity verification, informed consent, and clinical oversight are integral to ensure safety and regulatory compliance.
This content is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Do not use it to replace a consultation with a qualified healthcare professional who can evaluate your individual health needs. Always speak with your doctor, pharmacist, or licensed prescriber before starting, changing, or stopping any medication, and seek immediate medical care for urgent symptoms. The authors and publishers are not responsible for any outcomes related to the use or misuse of this information.
Clonidine is a central alpha-2 adrenergic agonist that lowers sympathetic nerve activity. This reduces heart rate and blood vessel tone, lowering blood pressure and producing calming effects that can help with ADHD, withdrawal symptoms, and hot flashes.
It is approved for high blood pressure and for ADHD in extended-release form. Clinicians also use it off-label for opioid withdrawal, menopausal hot flashes, anxiety, sleep disturbances, Tourette syndrome adjunctive therapy, and certain pain protocols.
Clonidine is available as immediate-release tablets, extended-release tablets (for ADHD), and once-weekly transdermal patches. An injectable form exists for specialized settings, but not for routine outpatient use.
Oral clonidine begins lowering blood pressure within 30 to 60 minutes, with peak effect in 2 to 4 hours. The transdermal patch has a delayed onset, typically taking 2 to 3 days to reach full effect.
A common starting dose is 0.1 mg by mouth twice daily, then titrated based on blood pressure and tolerability. The patch is often started at 0.1 mg/24 hours changed weekly, with adjustments as needed.
Extended-release clonidine is started low and increased gradually, often from 0.1 mg at bedtime to twice daily dosing, targeting 0.1–0.4 mg/day. It can be used alone or with stimulants to improve hyperactivity, impulsivity, and sleep.
Dry mouth, drowsiness, dizziness, headache, constipation, fatigue, and low blood pressure are common. Some people experience slow heart rate, nausea, or irritability early on.
Seek medical help for fainting, very slow heartbeat, chest pain, severe dizziness, confusion, breathing problems, swelling, or signs of an allergic reaction. Sudden discontinuation can trigger dangerous rebound hypertension.
Stopping suddenly can cause a surge in blood pressure, headaches, agitation, tremor, and rapid heartbeat. Taper slowly under medical supervision, especially if you also take a beta-blocker.
Yes. Sedation and slowed reaction time are common, especially at the start or after dose increases. Avoid driving or operating machinery until you know how you respond.
Take it when you remember unless it’s near the next dose. Do not double up. If a patch loosens or falls off, follow product instructions to reapply or replace and inform your clinician if this recurs.
Apply to clean, dry, hairless skin on the upper arm or chest, pressing firmly for 10–30 seconds. Change weekly, rotate sites, and avoid heat sources (heating pads, hot tubs), which can increase drug absorption.
Alcohol, opioids, benzodiazepines, and other sedatives can increase drowsiness and dizziness. Tricyclic antidepressants and some antidepressants may blunt clonidine’s effect. Combining with beta-blockers raises the risk of bradycardia and complicated rebound; coordination is needed when starting or stopping either drug.
It can be effective but older adults are more sensitive to sedation, dizziness, and blood pressure drops. Lower starting doses and careful monitoring are recommended.
Clonidine is partly cleared by the kidneys, so reduced kidney function can increase drug levels. Dose adjustment and closer monitoring of blood pressure and heart rate may be needed.
Regular blood pressure and pulse checks are key. Report excessive sleepiness, dizziness, or mood changes. Inspect patch sites for skin irritation if using the transdermal form.
It’s best to avoid combining them. Alcohol intensifies clonidine’s sedative and blood-pressure–lowering effects, increasing the risk of fainting and accidents; wait until alcohol has fully worn off and discuss safe use with your clinician.
Data are limited. Clonidine may be used if benefits outweigh risks, but other options (such as methyldopa) are often preferred for chronic hypertension in pregnancy. If used, careful maternal and fetal monitoring is advised.
Clonidine passes into breast milk and may cause infant drowsiness, low blood pressure, or poor feeding. If used, monitor the infant closely and discuss alternatives with your healthcare provider.
Generally no. Continuing clonidine helps prevent rebound hypertension. Inform your surgical and anesthesia teams; they will manage dosing and monitor for low blood pressure or slow heart rate.
Sit or lie down immediately, hydrate if appropriate, and check your blood pressure if possible. Contact your clinician promptly; do not make abrupt dose changes without guidance.
Yes. Clonidine reduces autonomic withdrawal symptoms like sweating, anxiety, and restlessness. It can lower blood pressure, so dosing and monitoring should be guided by a clinician; an FDA-approved alternative is lofexidine.
Its sedating effect can improve sleep onset in some people, especially those with ADHD-related insomnia. Use under medical guidance, as excessive daytime sleepiness and low blood pressure can occur.
This is an emergency. Clonidine overdoses in children can cause profound sleepiness, slow breathing, small pupils, low blood pressure, and slow heart rate. Call emergency services or poison control immediately.
Both are alpha-2 agonists that improve hyperactivity and impulsivity. Guanfacine is more selective for alpha-2A receptors and often causes less sedation and dizziness, while clonidine may better address sleep onset problems and tics for some patients.
Clonidine typically causes more drowsiness and blood pressure lowering at comparable effect doses. Guanfacine’s longer half-life and selectivity often translate to gentler sedation.
Both lower blood pressure, but neither is first-line in most guidelines today. Guanfacine may have a smoother profile and fewer withdrawal issues; clonidine is available as a patch, which can aid adherence. Choice depends on tolerability, comorbidities, and clinician preference.
Methyldopa is better studied and historically preferred in pregnancy. Clonidine can be considered when needed, but data are more limited; decisions are individualized by obstetric and hypertension specialists.
Both reduce withdrawal symptoms via alpha-2 agonism. Lofexidine is FDA-approved for this indication and tends to cause less hypotension and bradycardia, but it is often more expensive and may require more frequent dosing.
No. Dexmedetomidine is an IV alpha-2 agonist used for monitored sedation in hospitals and ICUs. Clonidine is used orally or as a patch in outpatient settings; they share mechanisms but serve different clinical roles.
Tizanidine is indicated for spasticity and is generally preferred for that purpose. Clonidine is not a standard spasticity treatment; both can lower blood pressure and cause sedation, and tizanidine requires liver monitoring.
The patch provides steady levels and once-weekly dosing, helpful for adherence and fewer peaks and troughs, but has delayed onset and possible skin irritation. Tablets act faster and allow finer dose adjustments but require multiple daily doses and carry a higher risk of rebound if doses are missed.
Extended-release clonidine offers smoother symptom control, once- or twice-daily dosing, and is designed for ADHD. Immediate-release can be effective off-label but has more variable levels and must be dosed multiple times per day; they are not milligram-for-milligram interchangeable.
Both are older central alpha-2 agonists for hypertension. Clonidine is more widely available in multiple formulations (including patch) and is better studied for non-BP uses like ADHD and withdrawal; guanabenz is used less often due to side effects and limited availability.
Rilmenidine and moxonidine act mainly on imidazoline receptors with some alpha-2 activity, often causing less sedation and dry mouth. They are used in some countries but are not widely available in the United States.
Both can help tics; clonidine may offer more sleep-onset benefit due to stronger sedation, while guanfacine is often better tolerated during the day. Choice depends on target symptoms, daytime functioning, and side-effect sensitivity.
