Clonidine hydrochloride is a centrally-acting alpha-agonist hypotensive agent. The drug is FDA-approved to treat hypotension in adults and works by changing certain nerve impulses to relax blood vessels.1 Specifically, clonidine stimulates alpha-2 receptors in the central nervous system, which then decreases sympathetic activity and decreases both blood pressure and heart rate. Clonidine may be prescribed on its own or in conjunction with another drug and can be delivered through pills, transdermal patches, or parenterally.2
Clonidine is also FDA-approved to treat Attention Deficit Hyperactivity Disorder (ADHD).3 Although the exact mechanism of action is not known, clonidine is believed to regulate norepinephrine in the brain, a neurotransmitter linked to ADHD. Clonidine is not a stimulant, but may be prescribed alone or with stimulants.
For more information, including a MSDS sheet, please see PNA’sClonidine page.
Hypertension: Clonidine is approved to treat hypertension through different delivery modes: orally, through a transdermal patch, or parenterally. Patches offer lower, steadier dosages than oral pills and are more convenient, but can be costlier.4 Parenteral administration is only recommended in patients who have cancer or neuropathic pain that may require concomitant opiates.5
ADHD: Clonidine is approved to treat children who have ADHD. The oral drug reduces ADHD symptoms alone or in combination with stimulants. Clonidine may also reduce aggression and insomnia associated with any concomitant stimulants.
Side Effects and Drug Interactions
Common side effects in patients taking clonidine include6:
Fatigue or insomnia
Nausea or vomiting
Nervousness or depression
Loss of appetite or weight gain
Decreased sexual ability
Muscle aches or cramps
Dry, itching, or blurry eyes
Patients experiencing the following symptoms should contact their healthcare provider right away:
Rash or hives
Difficulty breathing, swallowing, or talking
Swelling of the face or limbs
Any form of heart disease, or a history of heart disease or stroke
Slow heartbeat or other heart rhythm disorders
Tumors of the adrenal gland
Patients allergic to clonidine should not take this medication. Patients with any of the following conditions should consult with their physicians before starting this medication7:
Patients who are pregnant, or who plan on becoming pregnant, should consult their physician before starting this medicine.
Many drugs can have severe interactions with clonidine, including8:
Sedating drugs, such as those that contain alcohol or benzodiazepines
Medications that decrease heart rate, such as
Calcium channel blockers
Patients already on these drugs should consult their pharmacist or physician before starting clonidine.
Latest News and Research
Clonidine was developed in the mid-1960s as a side result from a drug being developed to treat nasal congestion.9 Since then, clonidine has been valuable not only as a drug, but also as a tool in understanding the importance of central α2-adrenoceptors and how they work.
Physicians often prescribe clonidine for off-label indications, including treatment of10:
Pain management in cancer patients
Withdrawal symptoms of alcohol, nicotine, and narcotics