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What is clonidine?

Clonidine is a medication primarily prescribed to treat high blood pressure. It acts within the brain to decrease the amount of adrenaline released. With decreased adrenaline available, blood pressure will decrease.

Why is clonidine prescribed?

The only FDA approved reason for clonidine use is to treat high blood pressure.
In addition, some doctors will prescribe clonidine to treat withdrawal symptoms from heroin, methadone, other opioids, and nicotine. It has occasionally been used to treat Tourette syndrome, attention deficit hyperactivity disorder, and for severe pain management in some patients that is not relieved by standard pain medications.

In what form can clonidine be used?

Clonidine can be administered as a tablet (immediate or extended release), transdermal patch, or epidural injection.

What are the side effects of clonidine?

The most common side effects include sedation, sleepiness, headaches, low blood pressure, and slow heart rate.

If I stop taking clonidine, are there side effects? 

When a person abruptly stops taking clonidine, they may experience an increase in blood pressure higher than baseline referred to as “rebound hypertension.” Nervousness, agitation, headache, or tremor may also occur. To reduce or prevent these symptoms, health care providers may gradually decrease the dose of clonidine over several days.

What happens if I take too much clonidine?

Clonidine can cause an unsafe drop in blood pressure or heart rate when too much is taken. In overdose it can also cause deep sedation and affect the ability to breathe normally.

What is the treatment for clonidine poisoning? 

There is no antidote for clonidine poisoning. If someone has taken too much clonidine they may need to be treated in a hospital with medications to increase the blood pressure and heart rate. In severe cases they may need to be placed on a breathing machine until the effects of the clonidine wear off.

Does clonidine interact with other medications?

When combined with other medications that cause low heart rate, low blood pressure, or sleepiness, the effects of clonidine may be increased. It is always important to tell a healthcare provider about all medications that are being taken.
Excessive sedation or lethargy can occur in overdose or when combined with alcohol, marijuana, or narcotics.


Created by Dan McCabe, MD, and Sean M, Bryant, MD. These answers are provided by volunteer medical toxicologists for the purpose of public education, and do not necessarily represent the policies or positions of the American College of Medical Toxicology.
All data and information provided in this FAQ is for informational purposes only. The American College of Medical Toxicology makes no representations as to accuracy, completeness, currentness, suitability, or validity of the content of the FAQ and will not be liable for any errors or omissions in this information or any losses, injuries, or damages arising from its display or use.

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