Key takeaways

  • Clonidine, which is used for high blood pressure, can cause side effects such as dry mouth, drowsiness, and constipation. Most side effects of clonidine are mild and manageable.
  • Suddenly stopping clonidine can lead to withdrawal symptoms such as increased blood pressure, nervousness, and headaches. It’s important to reduce the dosage gradually under medical supervision.
  • Older adults and people with an existing kidney problem may have a higher risk of severe side effects with clonidine. Your doctor will discuss potential risks of taking clonidine and determine whether you may need a lower dosage.

Clonidine comes as a tablet that you swallow. It’s also available as a patch, an injectable, or an extended-release tablet, but this article does not discuss these types.

This article describes clonidine’s side effects, also known as adverse effects. For more information about the drug, including details about clonidine’s uses, see this in-depth article.

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Some people may experience mild to serious side effects during their clonidine treatment. Examples of clonidine’s commonly reported side effects include:

  • dry mouth
  • drowsiness or sedation
  • dizziness
  • constipation

To learn more about some of these side effects, see the “Side effects explained” section.

Clonidine may cause mild side effects in some people. Examples of mild side effects that people taking clonidine have reported include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have any symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And don’t stop taking clonidine unless your doctor recommends it.

To learn more about some of these side effects, see the “Side effects explained” section.

Clonidine may cause mild side effects other than the ones listed above. See the drug’s prescribing information for details.

Serious side effects can occur during clonidine treatment, but this is uncommon.

Serious side effects that people taking clonidine have reported include:

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.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect while taking clonidine and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Allergic reaction

For some people, clonidine can cause an allergic reaction. But it’s not clear whether this side effect occurred in clonidine’s studies.

In general, symptoms of an allergic reaction can be mild or serious.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should keep taking clonidine.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to clonidine, they may have you switch to a different treatment.

Get answers to some frequently asked questions about clonidine’s side effects.

Yes, it’s possible that your risk of side effects may vary based on what dose of clonidine you take. For example, people taking a higher dose, such as 0.3 milligrams (mg), may have a higher risk of side effects than someone taking a lower dose, such as 0.1 mg.

Your doctor will monitor your blood pressure throughout your clonidine treatment. They may increase your dose over time to better manage your blood pressure. But this may raise your risk of side effects.

Your doctor will help determine the best dose of clonidine to manage your blood pressure. Most side effects are mild and may go away as you continue treatment. But if you experience bothersome side effects from clonidine, talk with your doctor about your dose.

Yes, it’s possible to have withdrawal symptoms if you suddenly stop taking clonidine. (Withdrawal symptoms are side effects that can occur when you stop taking a drug that your body has become dependent on.)

Withdrawal symptoms that can occur when suddenly stopping clonidine treatment may include:

  • nervousness or agitation
  • headache
  • tremor
  • increased blood pressure
  • stroke and death in rare cases

Due to these risks, you should not stop taking clonidine without first talking with your doctor. If you do need to stop treatment, your doctor will slowly decrease your dose over 2 to 4 da

Yes, bradycardia is a possible side effect of clonidine. Though this was not one of the more common side effects in studies of clonidine, it can occur.

Symptoms of bradycardia may include:

  • chest pain
  • dizziness
  • fatigue (low energy)
  • fainting

Bradycardia can also be a symptom of an overdose of clonidine. Overdose symptoms can occur if you take too much clonidine. It’s important to always take the dose of clonidine that your doctor prescribes.

 

Yes, weight gain and hair loss could occur with clonidine use. But these side effects were not common in people taking clonidine in studies. And these people may also have been taking other blood pressure medications, so it’s unknown if clonidine caused the hair loss and weight gain.

If you experience hair loss during your clonidine treatment that bothers you, talk with your doctor. In some cases, they may be able to recommend over-the-counter medications such as minoxidil (Rogaine) to treat your hair loss.

If you experience weight gain during your treatment that concerns you, talk with your doctor. Though it’s possible for clonidine to cause weight gain, heart failure may also be a side effect of clonidine. And a symptom of heart failure is weight gain. Your doctor can try to determine what may be causing your weight gain and the best treatment options for you.

Yes, older adults (ages 65 years or older) may have a higher risk of side effects from clonidine than younger people. This is because an older adult’s body may break down clonidine more slowly. This could cause the drug to build up in the body, which increases the risk of side effects.

Due to this risk, doctors may recommend that people ages 65 years or older take a lower dose of clonidine. Your doctor can determine what the best dose of clonidine is for you.

Learn more about some of the side effects clonidine may cause.

Dry mouth

Some people may experience dry mouth while taking clonidine. In fact, dry mouth was the most common side effect that people taking clonidine reported in studies.

What might help

If you develop a dry mouth during your treatment that bothers you, talk with your doctor. They may be able to recommend ways to manage this side effect, such as chewing gum or using mouthwash or lozenges.

Drowsiness or sedation

Drowsiness or sedation (extreme sleepiness) can occur from taking clonidine. These were common side effects that people taking clonidine reported in studies.

With sedation, you may move more slowly than usual or have slower reactions. Drowsiness can cause you to feel more sleepy than usual.

What might help

If you experience drowsiness or sedation from taking clonidine, talk with your doctor. In some cases, they may adjust your dose so that you take a higher dose before bed. This can help prevent sedation or drowsiness during the day.

Because clonidine can cause sedation or drowsiness, you should not drive or operate heavy machinery until you know how the drug will affect you.

Alcohol or other drugs that can cause sedation and drowsiness might worsen these side effects of clonidine. Your doctor may recommend that you avoid alcohol, other sedatives, or drugs that cause drowsiness while you’re taking clonidine.

Constipation

Clonidine may cause constipation in some people. This was a common side effect that people taking clonidine reported in studies.

What might help

If you develop constipation during your clonidine treatment, talk with your doctor. In some cases, they may recommend treatment options for your constipation. For example, taking an over-the-counter drug such as polyethylene glycol (MiraLAX) may relieve constipation.

Sexual side effects

Sexual side effects are possible while taking clonidine, but these side effects weren’t common in studies of the drug. Examples of sexual side effects that people taking clonidine reported include:

What might help

If you have any sexual side effects during your treatment that bother you, talk with your doctor. They may recommend treatment for these side effects. For example, sildenafil (Viagra) may be used to treat ED. It’s important to note that many drugs used to treat ED, such as sildenafil, may lower your blood pressure. In some cases, this may be unsafe if you’re taking clonidine.

If you’re concerned about the sexual side effects of clonidine, talk with your doctor about your treatment options.

Keeping track of side effects

During your clonidine treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how it affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how clonidine affects you. They can then use this information to adjust your treatment plan if needed.

Clonidine may not be right for you if you have certain medical conditions. These are known as drug-condition interactions. Other factors may also affect whether clonidine is a good treatment option for you.

Talk with your doctor about your health history before starting clonidine. Factors to consider include those described below.

Slow or irregular heart rate: Because of the way clonidine works, it may cause bradycardia (slow heart rate). If you have preeexisting bradycardia or take another medication that lowers your heart rate, taking clonidine may worsen your condition. Your doctor may prescribe a lower dosage of clonidine to help prevent the risk of severe bradycardia.

Kidney problems: Before starting clonidine treatment, tell your doctor if you have any kidney problems. This drug is removed from your body by your kidneys. If your kidneys are not working well, clonidine levels can build up in your body. This can raise your risk of side effects. If you have a kidney problem, your doctor may prescribe a lower dose of clonidine. Or in some cases, they may prescribe a drug other than clonidine for your condition.

Allergic reaction: If you’ve had an allergic reaction to clonidine or any of its ingredients, your doctor will likely not prescribe clonidine. Ask them what other medications are better options for you.

Older adults: If you’re age 65 years or older, you may have a higher risk of side effects from clonidine. Your doctor may monitor you more closely during treatment to watch for side effects, and they may prescribe a lower dose of clonidine. Or in some cases, they may prescribe a drug other than clonidine for you.

Contact lenses: Clonidine may make your eyes dry, which can make contact lenses uncomfortable to wear. If you notice that your eyes are dry when taking clonidine, tell your doctor. They may recommend using eyedrops to relieve dry eye.

Alcohol and clonidine

Drinking alcohol while you’re taking clonidine is not recommended. This is because alcohol can increase the risk of side effects from clonidine, such as:

If you’re concerned about avoiding alcohol during your clonidine treatment, talk with your doctor.

Pregnancy and breastfeeding while taking clonidine

It’s unknown whether it’s safe to take clonidine during pregnancy. Human studies haven’t looked at this drug’s safety during pregnancy. But clonidine does cross the placenta, which means that a fetus would likely be exposed to the drug.

Taking clonidine while breastfeeding is not recommended. The drug passes into breast milk and could cause side effects in a child who is breastfed.

If you’re pregnant, breastfeeding, or planning to become pregnant or to breastfeed, talk with your doctor before taking clonidine.

Most side effects of clonidine are mild, but serious side effects are possible, too. If you have any questions about the side effects that clonidine can cause, talk with your doctor.

Examples of questions that may help you get started:

  • Can clonidine cause long-term side effects?
  • Do I have a higher risk of side effects due to my other medications?
  • Is my risk of side effects higher when I first start treatment?
  • Does my risk of side effects depend on the dosage I take?

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 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.