Clonidine is a generic drug that’s prescribed to treat high blood pressure in adults. As with other drugs, clonidine can cause side effects, such as dizziness, drowsiness, and dry mouth.

Clonidine comes as an immediate-release (IR) oral tablet. It isn’t available in a brand-name version. With IR medications, the active drug is released into your bloodstream right away after you take it.

Clonidine also comes in these other forms: oral liquid suspension, extended-release oral tablet, skin patch, and injection. This article only covers clonidine IR oral tablet.

Read on to learn about potential common, mild, and serious side effects of clonidine IR oral tablet. For a general overview, including details about its uses, see this other article about clonidine IR oral tablet.

Clonidine can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took clonidine in clinical trials:

* For more information about this side effect, see “Clonidine: Side effect specifics.”

Mild side effects can occur with clonidine use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to clonidine’s prescribing information.

Mild side effects that have been reported with clonidine include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking clonidine and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Clonidine: Side effect specifics.”

Clonidine may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to clonidine’s prescribing information.

If you develop serious side effects while taking clonidine, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • depression, which may include symptoms such as:
    • loss of interest in activities or hobbies you once enjoyed
    • fatigue
    • changes in sleep
    • difficulty concentrating
  • hallucinations (seeing or hearing things that aren’t real)
  • heart problems*

* For more information about this side effect, see “Side effect specifics.”

ALLERGIC REACTION

For some people, clonidine can cause an allergic reaction. In general, symptoms of allergic reaction can be mild or serious.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to clonidine, your doctor may recommend taking a different medication instead.

Clonidine may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Is there a risk of withdrawal with clonidine and is it life threatening?

Yes, there’s a risk of withdrawal if you stop taking clonidine suddenly. With withdrawal, you experience side effects after you suddenly stop taking a substance your body has become dependent on.

Withdrawal symptoms that were reported in studies of clonidine include:

  • headache
  • nervousness
  • agitation
  • tremor
  • increased blood pressure

These symptoms can be mild or serious. In rare cases, serious or life threatening withdrawal side effects can occur. These include brain swelling or stroke.

Taking a higher dose of clonidine may increase the risk withdrawal symptoms if clonidine treatment is suddenly stopped. Your risk of withdrawal increases further if you take clonidine with a beta-blocker medication, such as metoprolol. In this case, your doctor will have you stop taking the beta-blocker several days before gradually stopping clonidine treatment. This is to help lower the risk of withdrawal symptoms.

Do not stop taking clonidine without first talking with your doctor. To help lower your risk of withdrawal symptoms, your doctor will likely slowly decrease your dose over 2 to 4 days before stopping clonidine treatment. Talk with your doctor if you have questions about withdrawal symptoms or if you experience them after stopping clonidine.

Does the 0.1 milligram (mg) dose of clonidine cause fewer side effects compared with higher strengths of the drug?

It’s possible. Studies of clonidine report that side effects may occur more often at higher doses, especially dry mouth, dizziness, drowsiness, and constipation. However, most side effects of clonidine are temporary and tend to go away as your body gets used to the drug.

Talk with your doctor if you experience side effects when starting treatment with clonidine. They may adjust your dose to help ease your symptoms.

Is clonidine safe for older adults?

Clonidine is typically safe for older adults (ages 65 years and older) to take. However, older adults may be more sensitive to the side effects of clonidine, especially drowsiness and dizziness, which may increase the risk of falls.

Because of this, your doctor will typically prescribe other medications for high blood pressure first before deciding to prescribe you clonidine. They’ll likely prescribe a lower dose of clonidine at the start of treatment if they decide that clonidine is right for you.

If you have questions or concerns about older adults taking clonidine, talk with your doctor or pharmacist.

Learn more about some of the side effects that clonidine may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for clonidine.

Dry mouth

Dry mouth was the most common side effect reported in clinical trials of clonidine. Dry mouth happens when there isn’t enough saliva in your mouth to keep your mouth wet. This side effect is typically mild and goes away on its own as your body gets used to the drug.

Taking a higher dose of clonidine can increase the risk of experiencing dry mouth. Dry mouth can sometimes lead to other symptoms, such as dry lips or bad breath.

What you can do

If you have symptoms of dry mouth, you can try sucking on ice cubes or sugarless hard candy, or drinking some water. If your symptoms become bothersome, talk with your doctor. They can recommend additional ways to help relieve dry mouth symptoms, such as an over-the-counter saliva substitute. They may also recommend switching to a different medication to treat your condition.

Heart problems

In some people, clonidine can cause heart problems, such as a slow heart rate, congestive heart failure, and irregular heart rhythm. However, these side effects were rare in clonidine’s clinical trials. Symptoms of heart problems may include:

  • shortness of breath
  • feeling weak or dizzy
  • swelling in your lower legs and ankles
  • heart palpitations
  • fainting

The risk of heart problems may be higher if you take certain other medications, such as digoxin or calcium channel blockers. If you have a heart condition, such as atrioventricular block or heart rhythm problems, taking clonidine may worsen your condition.

What you can do

If your doctor thinks you have an increased risk of heart problems, they’ll likely check your heart rate regularly. If you experience any symptoms of heart problems listed above, be sure to talk with your doctor right away. They’ll examine you to determine the cause of your symptoms.

Before taking clonidine, discuss your health history with your doctor. Clonidine may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Disclaimer: Medical News Today 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 another 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.