Clonidine

Boxed warning:

Clonidine has a boxed warning for those who are pregnant, have recently given birth, or have recently undergone surgery. Due to the risk of developing an abnormal or unstable heart rate and blood pressure, epidural clonidine is not recommended for obstetrical, postpartum, or perioperative pain management.¹

What is clonidine?

Clonidine is a prescription-only drug belonging to a group of medications called alpha-2 agonists. It targets alpha-2 receptors, which are located in the brainstem and peripheral nervous system. An alpha-2 agonist, like clonidine, mimics chemicals in the body that normally bind to alpha-2 receptors to help combat stress and regulate blood pressure. Clonidine reduces heart rate and blood pressure by relaxing the blood vessels and increasing blood flow to the heart.² ³

What is clonidine used to treat?

Clonidine is approved by the US Food and Drug Administration (FDA) for the treatment of hypertension in adults in the generic form or as the brand name drugs Nexiclon XR and Catapres-TTS. The medication can be used alone or simultaneously with other antihypertensive agents.⁴

What You Need To Know About High Blood Pressure

What You Need To Know About Attention-Deficit Hyperactivity Disorder (ADHD)

The drug is also approved for treating attention-deficit/hyperactivity disorder (generic and Kapvay) in children aged 6–17 years, either alone or as an adjunct to stimulant medications.⁵

An injectable form of the drug can be used as an epidural (generic and Duraclon) alongside IV opiate medications for treating severe cancer pain in adults and children in a medically controlled setting.⁶

Clonidine is also used extensively for off-label therapies, meaning it is not US FDA-approved for those indications. Some of these conditions include:

• Pediatric hypertension⁷

• Alcohol, opioid, and benzodiazepine withdrawal⁸ ⁹

• Post-traumatic stress disorder

• Smoking cessation¹⁰

• Tic management in Tourette syndrome¹¹

• Dysmenorrhea¹²

• Neonatal abstinence syndrome¹³

Dosage forms and strengths

Clonidine is available in several formulations: immediate-release tablets, extended-release (long-acting) tablets, an injectable solution, and an extended-release patch.¹⁴

The available formulations and their strengths are as follows:

• Immediate-release tablets (generic): 0.1mg, 0.2mg, 0.3mg¹⁵

• Extended-release tablets (generic, Kapvay): 0.1mg, (Nexiclon XR): 0.17mg, 0.26mg¹⁶

• Solution for injection (generic, Duraclon): 500µg/mL for epidural administration¹⁷ ¹⁸ ¹⁹

• Transdermal patch (generic, Catapres-TTS): 0.1mg/24h, 0.2mg/24h, and 0.3mg/24h²⁰

Your doctor will prescribe a dose of clonidine based on your specific needs and diagnosis, other medications you are taking, your other health conditions, and your body's response to treatment.

How do you take clonidine?

You can take clonidine tablets (immediate- or extended-release) with or without food. Swallow the tablet whole, as crushing, chewing, or breaking them will raise the rate of clonidine release into the body, which may be harmful.²¹

The transdermal patch releases the prescribed amount of medication over each 24-hour period and is replaced weekly. Follow your doctor’s instructions regarding the placement of the patch, how to cover it if needed, and the method for disposal once removed. Apply the patch to a hairless area of skin on your arm or chest once every seven days. Ensure that the skin in the area is not cut, bleeding, or otherwise injured before applying the patch.²²

The injectable form is only administered by a healthcare professional in a medical setting.

Take clonidine exactly as prescribed. If you’re unsure about something, ask your doctor or pharmacist for clarification.

Seeing results

Immediate-release and extended-release clonidine tablets are designed to work differently in the body. The former works quickly, while the latter is slowly released into the bloodstream.

The immediate-release tablet can reduce blood pressure within 30 to 60 minutes. You will see the maximum pressure-reducing effects within two to four hours. Notably, extended-release tablets may take longer.²³ ²⁴

Who should not take clonidine?

Clonidine is contraindicated for people with known allergies to any of the medication’s active or inactive ingredients. Additionally, epidural administration of the injectable form is contraindicated for people with an infection at the injection site, those prone to abnormal bleeding, and patients taking anticoagulants. If you believe you may meet any of these criteria, inform your doctor.²⁵ ²⁶

Use caution when taking clonidine if you:²⁷

• Are pregnant or breastfeeding  

• Have kidney problems 

• Have a slow heart rate or heart rhythm disturbance

• Have any cardiovascular disease, heart failure, or a recent heart attack

• Have a history of a stroke

• Have Raynaud disease

• Are dehydrated

• Have a history of depression 

• Drink alcohol

Personalized dose adjustment is usually necessary for patients with these medical conditions. 

Finally, the safety and effectiveness of using clonidine in children with hypertension have not been well-established. Any use of the drug for this indication would be considered off-label.²⁸

Potential side effects of clonidine

Like any other drug, clonidine has the potential to cause side effects, including the following:²⁹

• Dry mouth

• Drowsiness

• Constipation

• Dizziness or fainting, particularly when standing up quickly

• Anxiety

• Headaches

• Nausea or vomiting

• Loss of appetite

• Abdominal pain

• Sexual dysfunction

• Skin reaction to the patch

These are generally mild and resolve without intervention. Speak with your doctor if you experience lasting side effects.

Rare but serious side effects of clonidine may include any of the following:³⁰

• Severe low blood pressure (hypotension)

• Swelling of the face, lips, or tongue (angioedema)

• Slow heart rate

• Abnormal liver enzymes

• Syncope (fainting)

• Depression

• Hallucinations

• Atrioventricular (AV) heart block

Seek urgent medical care if you experience a severe adverse effect while taking clonidine.

Overdose

Overdose symptoms relating to altered consciousness typically appear within 90 minutes, while those involving the cardiovascular system usually develop within four hours.³¹

Overdose symptoms include any of the following:³²

• Dizziness or fainting

• Drowsiness

• Slowed heart rate or palpitations

• Seizures 

• Weakness

• Confusion or irritability

• Shivering

• Hallucinations

• Respiratory depression or apnea

• Coma

• Small pupils

If you suspect an overdose, seek emergency medical care, even if your symptoms aren't causing immediate distress.  

Allergy information

Don't use clonidine if you have a history of an allergic reaction to this or a similar medication. A hypersensitivity reaction may include any of the following symptoms: 

• Hives (urticaria)

• Generalized rash 

• Swelling of the face, lips, or tongue (angioedema)

• Rapid heart rate

• Difficulty breathing or wheezing

• Vomiting

• Loss of consciousness

Long-term use of clonidine

Many people take clonidine long-term. While the risk of adverse effects increases with the prolonged use of many drugs, most of the common side effects associated with clonidine tend to resolve with time.³³

Long-term use of Kapvay has not been thoroughly evaluated. People taking Kapvay for extended periods should see their doctor regularly to monitor for safety and re-evaluate the drug’s effectiveness.³⁴

Clonidine and pregnancy

The US FDA designated clonidine as a pregnancy category C drug. Animal studies have demonstrated risk, and while there’s a lack of research involving pregnant women, the risk of harm to the fetus cannot be ruled out.³⁵ ³⁶

There is also a risk of withdrawal symptoms in the newborn whose mother has been on a regular dose of clonidine during the pregnancy, often requiring the baby to remain in the hospital until the effects lessen or resolve.³⁷

Clonidine and breastfeeding

Clonidine passes into breast milk and may cause symptoms of drowsiness or poor feeding in breastfeeding infants. There is insufficient data from studies in humans to determine the effect on milk production or the safety of breastfeeding while taking clonidine.³⁸

If you're pregnant, breastfeeding, or planning a pregnancy, speak with your doctor before starting clonidine. They will help you determine whether the benefits of using the drug during pregnancy and breastfeeding outweigh the potential risks.

Missed doses

If you forget a dose, take it as soon as you remember unless it’s nearly time for your next one. If that’s the case, skip the missed dose and proceed with your regular schedule.³⁹

Never take a double dose of clonidine to make up for a missed one. Doing so may lead to overdosing. Setting a reminder can help you take clonidine as scheduled.

Drug interactions

Taking clonidine alongside other drugs can cause unwanted or unanticipated effects. Review all of your current medications with your doctor before beginning clonidine. Some of the drugs known to interact with clonidine include:⁴⁰

• Alzheimer's disease medications like galantamine (Razadyne) and donepezil (Aricept)

• Antibiotics, including linezolid (Zyvox) and mefloquine (Lariam)

• Antidepressants, particularly monoamine oxidase inhibitors (MAOIs), such as tranylcypromine (Parnate), phenelzine (Nardil), and isocarboxazid (Marplan)

• Anti-nausea drugs, such as trimethobenzamide (Tigan), promethazine (Phenergan), and metoclopramide (Reglan)

• Antiviral medications for HIV, such as ritonavir, (Norvir), lopinavir/ritonavir (Kaletra), saquinavir (Invirase), and atazanavir (Reyataz)

• Chemotherapy drugs, including lorlatinib (Lorbrena)

• Diabetes medications like dulaglutide (Trulicity)

• Heart medicines:

  • Antiarrhythmics like procainamide (Pronestyl), propafenone (Rythmol), dronedarone (Multaq), and disopyramide (Norpace)

  • Digoxin (Lanoxin)

  • Ivabradine (Corlanor)

  • Ticagrelor (Brilinta)

• Other blood pressure medications:

  • Beta-blockers, such as atenolol (Tenormin), metoprolol (Lopressor), propranolol (Inderal), and others

  • Calcium channel blockers like (amlodipine (Norvasc), diltiazem (Cardizem), verapamil (Covera), and others

  • Guanfacine (Tenex)

• Multiple sclerosis medications like ozanimod (Zeposia), ponesimod (Ponvory), and fingolimod (Gilenya)

• Muscle relaxants, such as tizanidine (Zanaflex)

• Seizure medications, including carbamazepine (Tegretol) and lacosamide (Vimpat)

• Sleeping pills, such as doxylamine (Unisom)  

• Certain herbal supplements, including kava and kratom

Can I drink alcohol while taking clonidine?

Alcohol can amplify some of the side effects associated with clonidine. Further, clonidine increases sensitivity to alcohol. Both clonidine and alcohol have sedative effects, and taking them together can lead to severe sedation.⁴¹ ⁴² ⁴³ ⁴⁴

What to discuss with your doctor before starting clonidine

Before taking clonidine, discuss the following topics with your doctor:⁴⁵

• Your medication allergies and any previous reactions to medication

• All prescribed and over-the-counter drugs you currently take, including supplements and herbal preparations, even if you only take them occasionally

• Your current medical conditions, particularly high or low blood pressure, kidney disease, a recent heart attack or heart rhythm disturbance, cardiovascular disease, fainting, stroke, or depression

• If you are using or have recently taken any medication for high blood pressure

• The risks of taking the drug during pregnancy, while breastfeeding, or as a senior (65 years or older)

• Whether or not you drink alcohol or use other recreational drugs, the amount, and how frequently

• Any upcoming surgeries or dental procedures

• If your work or lifestyle involves hazardous activities demanding alertness, such as driving or operating machinery

Stopping clonidine

Continue to take clonidine as prescribed, even if you feel well. Don't stop the medication without speaking to your doctor. Suddenly discontinuing clonidine can cause unwanted symptoms, such as:⁴⁶

• Nervousness

• Agitation

• Headache

• Tremor

• Lightheadedness

• Rapid heart rate

• Severely elevated blood pressure

Ask your healthcare professional before deciding to discontinue clonidine. They will work with you to consider alternative therapies and help you plan a gradual reduction to avoid dangerous and uncomfortable withdrawal symptoms.

Drug approval history

• 1974: Clonidine earns US FDA approval.⁴⁷

Tips for taking clonidine

The following tips can help you take clonidine safely:

• When attempting to discontinue extended-release tablets, speak with your doctor about how to slowly taper your dose to prevent withdrawal symptoms.⁴⁸

• If your transdermal patch loosens before your scheduled change day, apply an adhesive cover.⁴⁹

• Avoid drinking alcohol while taking clonidine, as it can increase the risk of side effects.

• Watch your hydration status and keep up your fluid intake, particularly when the weather is hot or you’re spending time outdoors.

• Keep your medication in a dry place at room temperature and out of the reach of children.

Frequently asked questions

What special dietary instructions should I follow when taking clonidine?

If you take clonidine for high blood pressure, your healthcare professional may prescribe a low-salt diet because high sodium consumption can raise blood pressure. Low-fat, low-calorie diets are helpful for losing weight, another treatment for hypertension. Your doctor will likely recommend additional lifestyle changes like exercise and stress-reduction techniques. It is also important to stay well hydrated while taking clonidine.⁵⁰

Is clonidine a strong sleeping pill?

Clonidine is not US FDA-approved for the treatment of insomnia. If you're struggling to get a good night's sleep, speak with your doctor about treatment options.