Adverse Effects of Clonidine

Central Nervous System Effects

The American College of Cardiology/American Heart Association guidelines identify sedation and drowsiness as the most common CNS adverse effects of clonidine, occurring in the majority of patients 1, 2, 3
Confusion, dizziness, and fatigue are well-documented adverse effects of clonidine, particularly in older adults 1, 2
Depression can be precipitated or exacerbated by clonidine, according to the European Heart Association 2, 4
Delirium may occur, especially in elderly patients, as reported by the European Heart Association 2

Marked sinus bradycardia is a common pharmacological effect of clonidine, as stated by the American Heart Association in Circulation 5
Hypotension and orthostatic hypotension occur frequently, particularly in older adults, according to the American College of Cardiology and the European Heart Association 1, 2, 4, 6
Heart block can develop as a result of clonidine therapy, as reported by the American Heart Association in Circulation 5

The American College of Cardiology and the European Heart Association warn that abrupt discontinuation of clonidine can cause severe rebound hypertension and hypertensive crisis 1, 2, 4, 6
Severe rebound hypertension is a characteristic of clonidine withdrawal syndrome, as reported by the American College of Cardiology and the European Heart Association 1, 4, 6
Potential hypertensive crisis is a risk of clonidine withdrawal syndrome, according to the American College of Cardiology and the European Heart Association 1, 6

The American Heart Association recommends investigating alternative causes of twitching in patients on clonidine, including electrolyte disturbances, other medications, or underlying neurological conditions 5
The American College of Cardiology and the European Heart Association advise continuing to monitor patients on clonidine for established adverse effects, including sedation, hypotension, bradycardia, and dry mouth 1, 2, 3
The American College of Cardiology and the European Heart Association emphasize the importance of patient education about never abruptly stopping clonidine to prevent withdrawal syndrome 1, 4, 6

The American Academy of Pediatrics recommends obtaining a detailed cardiac history, including personal and family history of syncope, bradycardia, or conduction abnormalities, before initiating clonidine in patients with attention deficit hyperactivity disorder (ADHD) 7
The American Academy of Pediatrics suggests monitoring heart rate regularly during treatment with clonidine, particularly when combining it with digitalis, calcium channel blockers, or beta-blockers, to minimize the risk of severe bradycardia 7

The American Academy of Child and Adolescent Psychiatry reports that bradycardia, hypotension, and abdominal pain are recognized adverse effects of clonidine, especially when used in combination with stimulants for ADHD treatment, with a rate of bradycardia and hypotension in the rare to infrequent range (less than 1/100) 8
The American Academy of Pediatrics recommends that if cardiac risk factors are present, an ECG should be performed and cardiology referral considered before starting clonidine in patients with ADHD 7

The American College of Cardiology and European Heart Association emphasize that clonidine must be tapered rather than suddenly stopped to avoid severe rebound hypertension and hypertensive crisis 7