Can clonidine cause palpitations, hypertension, and changes in heart rate?

From the Guidelines

Clonidine can cause changes in heart rate and blood pressure, but it is more likely to decrease heart rate and blood pressure, rather than cause palpitations and hypertension, except in cases of abrupt discontinuation, which can lead to rebound hypertension and tachycardia. Clonidine is an alpha-2 adrenergic agonist commonly prescribed for hypertension, ADHD, anxiety disorders, and to manage withdrawal symptoms. According to the most recent and highest quality study, clonidine may be associated with decreased heart rate and blood pressure 1. While taking clonidine typically lowers blood pressure and heart rate, sudden discontinuation can trigger rebound hypertension and tachycardia (rapid heart rate), which may manifest as palpitations. This rebound effect occurs because the body adapts to clonidine's presence, and when removed suddenly, there's an excessive release of norepinephrine. To avoid these potentially dangerous cardiovascular effects, clonidine should always be tapered gradually under medical supervision. Patients should never stop taking clonidine without consulting their healthcare provider and should report any heart-related symptoms promptly. Additionally, some patients may experience bradycardia (slow heart rate) while actively taking clonidine as part of its intended therapeutic effect.

Some key points to consider when prescribing clonidine include:

• Monitoring heart rate and blood pressure regularly
• Tapering clonidine gradually when discontinuing the medication
• Obtaining a personal and family cardiac history before starting clonidine
• Performing additional evaluation, such as an electrocardiogram (ECG), if risk factors are present
• Referring to a pediatric cardiologist if the ECG is not normal

It is essential to weigh the benefits and risks of clonidine and to closely monitor patients for any adverse effects, particularly those related to cardiovascular health 1. By doing so, healthcare providers can minimize the risk of complications and ensure the safe and effective use of clonidine.

From the FDA Drug Label

The sympatholytic action of clonidine may worsen sinus node dysfunction and atrioventricular (AV) block, especially in patients taking other sympatholytic drugs There are post-marketing reports of patients with conduction abnormalities and/or taking other sympatholytic drugs who developed severe bradycardia requiring IV atropine, IV isoproterenol and temporary cardiac pacing while taking clonidine. Monitor heart rate in patients receiving clonidine concomitantly with agents known to affect sinus node function or AV nodal conduction, e.g., digitalis, calcium channel blockers, and beta-blockers. Sinus bradycardia resulting in hospitalization and pacemaker insertion has been reported in association with the use of clonidine concomitantly with diltiazem or verapamil. Hypertension may develop early and may be followed by hypotension, bradycardia, respiratory depression, hypothermia, drowsiness, decreased or absent reflexes, weakness, irritability and miosis.

Clonidine and Heart Effects: Clonidine may cause changes in heart rate, including bradycardia. It can also worsen existing sinus node dysfunction and atrioventricular (AV) block.

• Palpitations: The FDA drug label does not directly mention palpitations as a side effect of clonidine.
• Hypertension: Clonidine is actually used to treat hypertension, but in the context of overdose, hypertension may develop early, followed by hypotension. Key points to consider:
• Clonidine can affect heart rate and rhythm, particularly in patients with pre-existing conduction abnormalities.
• Patients taking clonidine should be monitored for changes in heart rate, especially when used with other medications that affect the heart. 2 2

From the Research

Clonidine's Effects on Heart Rate and Blood Pressure

• Clonidine is known to reduce blood pressure and heart rate oscillations in hypertensive patients 3.
• A study found that clonidine reduced the variability of blood pressure and heart rate, and also reduced the average blood pressure by 19.7 mm Hg for systolic, 10.6 mm Hg for diastolic, and 16.0 mm Hg for mean arterial pressure, and 1.0 beat/min for heart rate 3.
• Another study compared clonidine with guanfacine and found that both drugs reduced blood pressure, but clonidine had a greater effect on reducing heart rate and blood pressure variability 4.

Palpitations and Hypertension

• Abrupt clonidine withdrawal may be associated with sharp marked increases in catecholamine levels, heart rate, and blood pressure, which may induce nausea, vomiting, and palpitations 5.
• A study found that serious ventricular arrhythmias, including brief ventricular tachycardia, developed in two patients after abrupt clonidine withdrawal, suggesting that clonidine withdrawal syndrome may include cardiac arrhythmias 5.
• However, a review of studies on medications for attention-deficit hyperactivity disorder found that clonidine is associated with small decreases in mean systolic blood pressure, diastolic blood pressure, and heart rate, and does not cause statistically or clinically significant increases in QTc interval or sudden cardiac death 6.

Changes in Heart Rate

• Clonidine has been shown to reduce heart rate oscillations and decrease mean heart rate in hypertensive patients 3.
• A study found that clonidine reduced heart rate by 1.0 beat/min, and another study found that clonidine-XR (extended release) administered alone or in combination with psychostimulants to children and adolescents with ADHD resulted in small decreases in mean systolic blood pressure, diastolic blood pressure, and heart rate 3, 6.
• However, abrupt clonidine withdrawal may be associated with increases in heart rate and blood pressure, which may induce palpitations and other symptoms 5.