Clonidine extended-release oral tablet is a prescription medication used to treat attention deficit hyperactivity disorder (ADHD). Clonidine is available in various forms, some of which come in generic and brand-name versions.

Clonidine is available as a patch you apply to your skin, a liquid solution for injection, an oral suspension, an oral tablet, and an extended-release (ER) oral tablet. (“Extended release” means the drug is slowly released into your body over a long period of time.) This article focuses on the ER oral tablet.

Clonidine ER oral tablets were available as the brand-name drug Kapvay, which has been discontinued. They’re now only available as a generic drug. Generic drugs usually cost less than the brand-name version.

Clonidine ER oral tablets are used to treat symptoms of attention deficit hyperactivity disorder (ADHD). Doctors may prescribe the drug for this use for adults and children ages 6 to 17 years.

This drug may be used as part of a combination therapy. That means you may need to take it with other drugs.

Other uses for clonidine

Doctors may prescribe other forms of clonidine for other uses.

For example, clonidine immediate-release oral tablet and patch are used to treat hypertension (high blood pressure) in adults. (“Immediate release” means the drug is released into your body right away.)

Clonidine liquid solution for epidural infusion (an injection into the epidural space around the spinal cord given continuously) is used to relieve severe pain in people with cancer.

For more information about the uses of the different forms of clonidine, talk with your doctor or pharmacist.

Clonidine belongs to a group of drugs called centrally acting alpha2-adrenergic agonists. It isn’t known exactly how clonidine ER oral tablets work to reduce symptoms of ADHD. Clonidine is known to work in the part of the brain that helps regulate behavior, attention, and how people express emotion.

Clonidine can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking clonidine. These lists do not include all possible side effects.

For more information on the possible side effects of clonidine or tips on managing a difficult side effect, talk with your doctor or pharmacist.

More common side effects

Mild side effects may go away within a few days to a couple of weeks. Talk with your doctor or pharmacist if they’re more severe or don’t go away. The more common side effects that can occur with clonidine include:

Serious side effects

If you experience any of these serious side effects, call your doctor right away. If your symptoms are potentially life threatening or if you think you’re experiencing a medical emergency, call 911. Serious side effects can include:

  • increased then decreased blood pressure
  • slower or faster heart rate
  • uneven heart rate
  • dizziness when you stand
  • passing out
  • slowed breathing or difficulty breathing
  • chest pain
  • hallucinations (seeing things that aren’t there)

Clonidine can interact with several other medications. Different interactions can cause different effects. For instance, some can interfere with how well a drug works, while others can cause increased side effects.

The following text gives examples of medications that can interact with clonidine. Not all drugs that may interact with clonidine are listed, however.

Before taking clonidine, be sure to tell your doctor and pharmacist about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Drugs that increase drowsiness

Do not combine these drugs with clonidine. Taking these drugs with clonidine might increase drowsiness:

  • barbiturates such as:
    • phenobarbital
    • pentobarbital
  • phenothiazines such as:
    • chlorpromazine
    • thioridazine
    • prochlorperazine
  • benzodiazepines such as:
  • opioids (drugs for pain) such as:
    • oxycodone (OxyContin)
    • hydrocodone
    • morphine (Apokyn)
  • other sedating drugs

Tricyclic antidepressants (TCA)

Combining TCAs with clonidine can increase your blood pressure. Examples of these drugs include:

Heart drugs

Combining certain heart drugs with clonidine can slow your heart rate. This can become severe. You may need to go to the hospital or have a pacemaker. If you’re taking one of these medications, clonidine may not be the best choice for you.

Examples of these heart drugs include:

Antipsychotic drugs

If you take these drugs with clonidine, you may get dizzy or have trouble balancing when you sit after lying down or stand after sitting. This is called orthostatic hypotension. Examples of these drugs include:

Blood pressure drugs

Combining blood pressure drugs with clonidine may lower your blood pressure too much. This raises your risk of passing out. Examples of these drugs include:

This drug comes with several warnings.

Surgery

You can take clonidine up to 4 hours before a surgery. Do not take it within the 4 hours right before your surgery. You can restart it right away after surgery.

Allergies

Don’t use this medication if you’ve had an allergic reaction to clonidine tablets or parts of the clonidine patch in the past.

Taking oral clonidine after having a skin reaction to the clonidine patch can cause a rash over your whole body, itching, and possibly a severe allergic reaction.

A severe allergic reaction may cause:

  • difficulty breathing
  • swelling of your throat or tongue
  • hives

Alcohol interaction

Combining alcohol with clonidine may cause a dangerous sedative effect. It may slow your reflexes, affect your judgment, and cause sleepiness.

Warnings for certain groups

For people with heart problems: This may cause low blood pressure, low heart rate, and heart disease. This medication decreases blood pressure and heart rate. You may be at risk of more serious side effects if you already have low blood pressure or a low heart rate.

For people who get dizzy when standing: This condition is called orthostatic hypotension. Clonidine can worsen this condition. Do not stand up too quickly, and make sure not to get dehydrated while taking this drug. These can increase your dizziness and risk of fainting.

For people with syncope (fainting): Clonidine can worsen this condition. Don’t stand up too quickly, and make sure not to get dehydrated while taking this drug. These can increase your dizziness and risk of fainting.

For pregnant females: There haven’t been enough studies done in humans to be certain how the drug might affect a fetus. Research in animals has shown adverse effects occurring to the fetus when the pregnant animal takes the drug.

Speak with your doctor if you’re pregnant or plan to become pregnant. Clonidine should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus.

For females who are breastfeeding: Clonidine may pass into your breast milk and can cause side effects in a child who is breastfeeding. Tell your doctor if you’re breastfeeding. You may need to decide whether to stop breastfeeding or stop taking clonidine.

For older adults: This medication may cause low blood pressure, which can result in dizziness and increase the risk of falling.

For children: This drug hasn’t been studied in children with ADHD under the age of 6 years.

Note: The use of binary terms such as “female” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

The clonidine dosage your doctor prescribes will depend on several factors. These include:

  • your age
  • the condition you are taking it to treat
  • the severity of your condition
  • other medical conditions you have
  • how you react to the first dose

Typically, your doctor will start you on a low dosage and adjust it over time to reach the dosage that’s right for you. They’ll ultimately prescribe the smallest dosage that provides the desired effect.

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to suit your needs.

Form and strength

Form: oral extended-release tablet

Strengths: 0.1 mg

Dosage for attention deficit hyperactivity disorder (ADHD)

Adult dosage (ages 18 years and older)

  • The starting dose is 0.1 mg, taken at bedtime.
  • Doses may be increased by an additional 0.1 mg per day every week until symptoms are better or your reach the daily maximum.
  • Total daily doses are 0.1 to 0.4 mg per day.
  • The total daily dose is divided into two doses taken twice per day.
  • If you’re stopping clonidine treatment, the total daily dose should be decreased by 0.1 mg every 3 to 7 days.

Child dosage (ages 6 to 17 years)

The dosage for children ages 6 to 17 years is the same as for adults.

Child dosage (ages 0 to 5 years)

A safe and effective dose hasn’t been established for this age group.

Special dosage considerations

If you have kidney disease: The starting dosage may be lower for people with kidney disease. The dosage may be increased based on a person’s blood pressure.

Clonidine is a long-term medication. It comes with serious risks if you don’t take it as prescribed.

If you don’t take it at all or not on schedule

Your signs and symptoms of ADHD may get worse.

If you stop suddenly

It’s important not to stop taking this drug abruptly. This can lead to a withdrawal reaction. Side effects may include:

  • headaches
  • tremors
  • rapid increase in blood pressure

What to do if you miss a dose

If you miss a dose, skip the missed dose and take the next dose as scheduled.

Don’t take more than the prescribed total daily amount of clonidine in a 24-hour period.

How to tell if the drug is working

You may be able to tell this drug is working if you notice reduced symptoms of your condition, especially attention, hyperactivity, and impulsivity.

Keep these considerations in mind if your doctor prescribes clonidine for you.

General

  • You can take clonidine with or without food.
  • Take clonidine in the morning and at bedtime: The total daily dose is split into two doses. Each dose is usually the same, but sometimes a higher dose is needed. If you have a higher dose, take it at bedtime.
  • Don’t crush, chew, or cut this medication.

Storage

  • Store this drug at a room temperature between 68°F and 77°F (20°F and 25°C).
  • Keep the medication away from light.
  • Keep this drug away from areas where it could get wet, such as bathrooms.

Refills

A prescription for this medication is refillable. You should not need a new prescription to refill this medication. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry it with you or in your carry-on bag.
  • Don’t worry about airport X-ray machines. They can’t hurt this drug.

Clinical monitoring

Your doctor may do tests during your treatment with this drug. These tests can help make sure the drug is working and that you’re staying safe during therapy. Your doctor may:

  • check your kidney function to see whether your starting dose needs to be lower.
  • do an electrocardiogram or other heart tests to check how your heart is working and to make sure you aren’t having side effects.
  • monitor your blood pressure and heart rate to make sure this drug is working.

The cost of these tests will depend on your insurance coverage.

Other medications are available to treat your condition. Some may be more suitable for you than others. Talk with your doctor about possible alternatives.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.