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Side Effects of Clonidine (Kapvay)


Side Effects of Clonidine (Kapvay)

Clonidine, also known as the brand Kapvay, is used for the treatment of hypertension (high blood pressure) and attention deficit hyperactivity disorder (ADHD). Kapvay is also used to treat Tourette syndrome, nicotine and opioid withdrawal. The drug may be given orally or through a transdermal patch placed on the skin. People with chronic pain may receive clonidine injection into the epidural space of the spine.

Serious Side Effects

The FDA warns patients of serious adverse effects Kapva causes on the cardiovascular and nervous system. The drug may cause bradycardia (slowing of the heart) and hypotension (drop in blood pressure). At higher doses, Kapvay may cause central nervous system depression that impairs a person’s ability to perform mental and physical activities. These effects may be particularly common and severe in older individuals, and should be used with caution or avoided in people older than 65.

Side Effects on the Epidural Space of the Spine

When Kapvay is administered into the epidural space in the spine, it causes different effects than orally or absorbed from a transdermal patch, according to the FDA. The most common epidural side effects are hypotension (low blood pressure), dizziness, and confusion. Xerostomia or dry mouth may also occur in about 13% of patients.


Importantly, the studies used to identify and measure epidural clonidine adverse effects were performed in people with cancer who were also receiving epidural morphine. Therefore, it is not truly possible to separate clonidine side effects from morphine side effects.


A rare side effect of epidural Kapvay is hallucinations. Hallucinations are the sensation of seeing, hearing or otherwise sensing things that are not actually present in the physical world. This side effect goes away once Kapvay treatment has been stopped (Kapvay label reported by the FDA).

Common Side Effects

Certain Kapvay side effects occur in more than 10% of people who take the oral from of the drug. These include:


  • Drowsiness
  • Headache
  • Fatigue
  • Contact dermatitis (irritated skin)
  • Stomach pain
  • Xerostomia (dry mouth)

(Kapvay label as reported by the FDA).


Xerostomia or dry mouth can be severe and may prompt patients to stop taking the drug. Xerostomia is usually the most troubling side effect for patients. As many as four in ten people who take Kapvay will have some degree of dry mouth, but only a portion of effected patients will find the effect severe.

About Pharmacogenetic Testing

Kapvay can cause side effects in patients. Some patients will be able to take the medication well and not experience severe side effects. This is because of inter individual patient variability and the gene variations in individuals.


The side effects that occur with Kapvay delivered through a transdermal patch are roughly the same as the Kapvay adverse effects listed. Because the transdermal patch slowly releases clonidine into the skin, the severity of the reactions is less than it might be with the oral form of the drug.

Know Your Risk with the Rxight® Genetic Test

Rxight® pharmacogenetic testing provides information about how you will react to Kapvay before you even take the drug. It’s a safe way to find drug compatibility with the person and avoid potential medication problems. If the medicine is not ideal, an alternative will be offered. Rxight® helps your health care provider in creating the most effective and safest treatment plan for you.


Call us to learn more about Rxight® pharmacogenetic testing, at 1-888-888-1932 or email us at support@Rxight.com.


Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry

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