7 mins read

Overview: Clonidine is a medicine used to treat Attention Deficit Hyperactivity Disorder, also known as ADHD. It works to help improve hyperactivity and attention. Common side effects include drowsiness, irritability, nightmares, trouble sleeping, constipation, dry mouth, lack of appetite, and dizziness. Serious side effects are less common but can include allergic reactions, low blood pressure and heart rate, decreased alertness and coordination, and heart rhythm changes. Clonidine comes as a tablet or liquid that is taken by mouth.

Uses

What is clonidine used for?

Clonidine (Kapvay, Onyda XR) is commonly used for treating Attention Deficit Hyperactivity Disorder (ADHD).  

Clonidine may also be used for other conditions as determined by your healthcare provider.

For information about clonidine for blood pressure see Clonidine (Catapres, Nexiclon XR).

An injectable form of clonidine is used for severe cancer pain. See Clonidine epidural for more information. 

How does clonidine work (mechanism of action)?

Clonidine affects a chemical in the brain called norepinephrine, which controls attention and hyperactivity.

How is clonidine supplied (dosage forms)?

Brands and other names

  • Onyda XR

Dosage forms and strengths

  • 0.1 mg extended-release oral tablets
  • 0.1 mg/mL extended-release oral suspension

How should I store clonidine?

Oral Tablets. Clonidine extended-release tablets should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. 

Oral Liquid. Clonidine extended-release oral liquid should be stored in its original container at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Protect from light. Throw away any unused medicine 60 days after opening the bottle. 

Side Effects

What are the most common side effects of clonidine?

The most common side effects of clonidine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Drowsiness
  • Tiredness
  • Irritability
  • Nightmares
  • Trouble sleeping
  • Constipation
  • Dry mouth
  • Lack of appetite
  • Dizziness

There may be other side effects of clonidine that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of clonidine?

While less common, the most serious side effects of clonidine are described below, along with what to do if they happen.

Severe Allergic Reactions. Clonidine may cause allergic reactions, which can be serious. Stop taking clonidine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Low Blood Pressure (Hypotension). Clonidine may cause low blood pressure. If you feel faint or dizzy, lie down. Tell your healthcare provider right away if you have any of the following symptoms of low blood pressure.

  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tired

Heart Rate Changes. Clonidine can make your heart beat slower than normal (bradycardia). Call your healthcare provider right away if you have any of the following symptoms of bradycardia. 

  • Feeling lightheaded, dizziness, or fainting
  • Confusion
  • Feeling weak or easily tired 
  • Slow heartbeat or feeling of skipped heartbeats 
  • Chest pain
  • Shortness of breath

Decreased Alertness or Coordination. Clonidine can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how clonidine affects you.

Heart Rhythm Changes. Clonidine may cause heart rhythm problems that can lead to an irregular heartbeat and fainting. Some people have a higher risk of this, including people with existing heart disease or who take other medicines that affect the heart. Get emergency help if you have any of the following signs of heart rhythm changes.

  • Chest pain
  • Shortness of breath
  • Feeling dizzy, lightheaded, or fainting
  • Changes in your heart rate or rhythm, such as a fast, slow, pounding, or skipping heartbeat

Withdrawal Reactions. If you stop clonidine suddenly, it could lead to withdrawal symptoms. Do not stop taking clonidine without talking with your healthcare provider. Your healthcare provider can tell you how to stop clonidine to reduce the risk of withdrawal reactions. Call your healthcare provider right away if you have any of the following symptoms.

  • Increased blood pressure
  • Headache
  • Increased heart rate
  • Nervousness
  • Chest tightness
  • Nausea
  • Flushing

Warnings & Precautions

Who should not use clonidine?

Allergies to Ingredients. People who are allergic to any of the following should not take clonidine.

  • Clonidine
  • Kapvay
  • Onyda XR
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific clonidine products they stock.

What should I know about clonidine before using it?

Do not take clonidine unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share clonidine with other people, even if they have the same condition as you. It may harm them.

Keep clonidine out of the reach of children.

Avoid becoming too hot or dehydrated to lower the chance you will be dizzy or faint. Try to drink plenty of water, limit your exposure to the heat and sun, and wear light and breathable clothing.

Do not chew, cut, or crush clonidine extended-release tablets.

Gently shake clonidine oral liquid in an up-and-down motion for at least 10 seconds before taking the medicine. Use the oral dosing dispenser and bottle adapter that comes with clonidine oral liquid. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Follow the Instructions for Use leaflet that comes with your clonidine oral liquid prescription or talk to your healthcare provider to learn more about how to properly take the medicine.

What should I tell my healthcare provider before using clonidine?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if clonidine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Kidney problems
  • High or low blood pressure
  • History of passing out or fainting
  • Heart problems including heart rhythm problems or a slow heart rate
  • History of a stroke or heart attack

Other Medicines and Supplements. Clonidine may interact with other medicines and supplements. Before taking clonidine, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details. Also tell your healthcare provider if you have used clonidine transdermal patches (Catapres-TTS) and have had an allergic reaction. 

Pregnancy. It is not known if or how clonidine could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take clonidine while you are pregnant or trying to get pregnant. If you become pregnant while taking clonidine, you can sign up for the National Pregnancy Registry of ADHD Medications by calling 866-961-2388 or at www.womensmentalhealth.org/adhdmedications. This registry collects safety information about the use of ADHD medicines during pregnancy.

Breastfeeding. Clonidine passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take clonidine while breastfeeding.

Interactions

Does clonidine interact with foods or drinks?

There are no known interactions between clonidine and foods or drinks.

Do not drink alcohol while taking clonidine. The risk of dizziness and drowsiness is increased if you drink alcohol.

Does clonidine interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking clonidine.

  • A medicine for high blood pressure
  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
  • A calcium channel blocker, such as diltiazem (Cardizem CD and others) or verapamil (Verelan, Verelan PM), which is a medicine used for high blood pressure or other conditions
  • A beta-blocker, such as metoprolol (Lopressor, Toprol XL, and others), atenolol (Tenormin), or propranolol (Inderal LA, Innopran XL), which is a medicine that may be used for certain heart conditions or to lower blood pressure
  • A tricyclic antidepressant, such as amitriptyline, nortriptyline, or protriptyline, even if it is not used for depression
  • Any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, or medicines for anxiety

This may not be a complete list of medicines that can interact with clonidine. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much clonidine?

If you or someone else has used too much clonidine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of clonidine?

If you miss a dose, skip the missed dose and take the next dose as scheduled. Do not take double or extra doses.