Klonopin (clonazepam) is a brand-name prescription medication. The Food and Drug Administration (FDA) has approved it to treat certain adults with:

In addition, the FDA has also approved Klonopin to treat seizure disorders in children of all ages.

Here are some fast facts about Klonopin:

Depending on your condition and treatment plan, doctors may recommend taking Klonopin short term or long term. For example, it may be beneficial to take Klonipin long term to treat a seizure disorder.

However, if you’re taking Klonopin for panic disorder, your doctor may recommend taking the drug short term. It’s unknown if Klonopin is effective at treating this condition long term. So, before you start taking Klonopin, talk with your doctor about the best treatment plan for you.

As with other drugs, Klonopin can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Klonopin, including details about its uses, see this article.

Klonopin 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 Klonopin in clinical trials:

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

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

Mild side effects that people taking Klonipin have reported 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 side effects of the medication. If you develop a side effect while taking Klonopin and want to tell the FDA about it, visit MedWatch.

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

Klonopin may cause serious side effects. Though serious side effects aren’t common, they can occur. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Klonopin’s prescribing information.

If you develop serious side effects while taking Klonopin, 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:

  • Seizures. Symptoms can include:
    • confusion
    • loss of consciousness
    • uncontrolled movement of the arms or legs
  • Anger, depression, or other mood changes. Symptoms can include:
    • feeling hopeless
    • irritability
    • difficulty falling asleep or staying asleep
  • Difficulty breathing (respiratory depression). Symptoms can include:
    • slow, shallow breaths
    • sleepiness
    • shortness of breath
  • Low blood pressure. Symptoms can include:
    • blurry vision
    • confusion
  • Suicidal thoughts or behaviors. Symptoms can include:
    • thoughts of suicide
    • new or worsening depression
    • impulsiveness
  • Impaired thinking or memory loss.
  • Problems with motor skills, such as walking.
  • Risk of physical withdrawal and dependence.*
  • Risk of serious injury or death if taken with opioids.*
  • Risk of misuse or addiction.†
  • Severe allergic reaction.

* Klonopin has a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effect specifics” section below.
Klonopin has a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA). To learn more, see the “Klonopin and Misuse” section below.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Click here for more links and local resources.

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Klonopin is only approved to treat children with certain seizure disorders. This medication is not currently approved to treat children with panic disorder.

Typically, side effects that children experience are similar to those in adults. However, children can be at a higher risk of paradoxical reactions. Paradoxical reactions occur when someone has the opposite reaction than what is expected.

So, for example, sleepiness is one of the common side effects of Klonopin. However, if a child has a paradoxical reaction, they may become more energetic after taking Klonopin.

If you’re concerned about side effects that your child may experience from taking Klonopin, talk with their doctor.

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

What are the long-term side effects of Klonopin?

Although rare, it’s possible for people taking Klonopin to experience long-term side effects. Examples of long-term side effects that can occur from this medication include:

* Klonopin has a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effect specifics” section below.
Klonopin has a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA). To learn more, see the “Klonopin and Misuse” section below.

If you’re concerned about developing long-term side effects from taking Klonopin, talk with your doctor or pharmacist. They can discuss the risk of long-term side effects occurring and the best ways to treat or help prevent them.

Does Klonopin cause weight gain?

It is possible for Klonopin to cause weight gain. Though this was not a common side effect reported in clinical trials, it can occur. It’s unknown how often weight gain may occur from taking Klonopin.

If you experience weight gain during your treatment with Klonopin, talk with your doctor. They can help determine what may be causing the weight gain. They may also be able to help with ways to manage your weight.

If you have additional questions about Klonopin and weight gain, talk with your doctor or pharmacist.

Is it possible to have overdose symptoms from taking too much Klonopin?

Yes, you can develop overdose symptoms from taking too much Klonopin. In fact, taking too much Klonopin can even be life threatening. Due to these possible risks, Klonopin has a boxed warning for the risk of misuse or addiction, which can lead to overdose symptoms. For more information on this risk, see the “Klonopin and misuse” section below.

It’s important to only take the dose of Klonopin that your doctor prescribes for you. Do not take more medication than your doctor recommends. If you feel that Klonopin is not working for you, talk with your doctor about other treatment options that may be available.

It’s possible for any benzodiazepine, including Klonopin, to increase the risk of misuse or addiction. In fact, Klonopin has a boxed warning for this risk. A boxed warning is the most serious warning recommended by the FDA. The purpose of a boxed warning is to alert patients and prescribers about the risks of taking a medication.

It’s possible that taking Klonopin may increase your risk of misuse or addiction. Sometimes, misusing a drug can lead to serious side effects, including overdose, which can be life threatening. Examples of Klonopin overdose symptoms may include:

  • sleepiness
  • confusion
  • decreased reflexes
  • coma

If you develop symptoms of a Klonopin overdose, call 911 or see a doctor right away.

Misusing a medication means using it in a way that’s different than how your doctor prescribed it for you. So, it’s important that you always follow your doctor’s instructions on how to take your medication. Before you start treatment with Klonopin, tell your doctor if you have a history of misusing a medication. In this case, they may monitor you more often for symptoms of misuse or addiction.

In order to prevent the misuse of Klonopin, doctors typically prescribe the lowest possible dose of the drug for the shortest possible time.

If you have questions or concerns about the possibility of misuse or addiction occurring from taking Klonopin, talk with your doctor pharmacist.

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

Risk of physical withdrawal and dependence

It’s possible for Klonopin to cause physical withdrawal and dependence. Withdrawal and dependence can occur even if you take Klonopin as prescribed by your doctor. Because of this, Klonopin has a boxed warning for the risk of withdrawal or dependence occurring.

Dependence can occur when your body is used to taking a medication, and you need the drug in order to feel normal. Withdrawal can also occur when you stop taking a drug that your body has become dependent on.

Examples of Klonopin withdrawal side effects can include:

The early stage of withdrawal can occur soon after you stop taking Klonopin. However, you may experience protracted withdrawal, which can last from weeks to even months after stopping Klonopin.

You may be at a higher risk of dependence or withdrawal if you take a higher dose of Klonopin or take the drug for a long time.

What you can do

In order to help prevent withdrawal symptoms, talk with your doctor before stopping treatment with Klonopin. They will likely recommend slowly decreasing your dose of the drug over time. This can reduce your risk of developing withdrawal symptoms. In addition, they may recommend a different treatment option for your condition.

If you have additional questions or concerns about the risk of withdrawal or dependence from taking Klonopin, talk with your doctor or pharmacist.

Risk of serious injury or death if taken with opioids

Taking a benzodiazepine drug, such as Klonopin, with an opioid drug may cause serious injury or be life threatening. Because of this, Klonopin has a boxed warning for the risk of serious injury or death if the drug is combined with an opioid. A boxed warning is the most serious warning that the FDA recommends. The purpose of a boxed warning is to alert patients and prescribers about the risks of taking a medication.

Klonopin and opioid drugs can cause serious side effects, which can be life threatening. Examples of these side effects may include:

So, taking these drugs together can further increase your risk of side effects.

What you can do

Always tell your doctor if you are taking an opioid drug before starting treatment with Klonipin. They may be able to recommend a different medication for you so that you do not combine the two drugs. If that’s not possible, your doctor may recommend taking the lowest possible doses of Klonopin and the opioid drug. They will also likely recommend taking the combination for the shortest time possible.

Before you start taking Klonopin along with an opioid drug, your doctor will discuss the risks with you. If you have additional questions or concerns, talk with your doctor or pharmacist.

Sleepiness

You may experience sleepiness from taking Klonopin. In fact, sleepiness was one of the most common side effects reported in clinical trials of Klonopin.

What you can do

If you notice sleepiness that’s bothersome to you while you are taking Klonopin, talk with your doctor. They may be able to recommend ways to help manage this side effect. For example, they may reduce your dose of Klonopin to see if your sleepiness improves.

Nausea

You may develop nausea from taking Klonopin. Nausea wasn’t a common side effect in clinical trials of Klonopin. In fact, nausea was only reported in people taking Klonopin for seizure disorders. This side effect was not seen in studies of people taking Klonopin for panic disorder.

What you can do

If you develop nausea during your treatment with Klonopin, talk with your doctor. They may be able to help recommend ways to reduce this side effect from occurring. For example, taking a medication with food might help reduce symptoms of nausea.

Sexual side effects

It’s possible to develop sexual side effects during your treatment with Klonopin. Though sexual side effects were not commonly reported in clinical trials of Klonopin, they can occur.

Sexual side effects were seen in people taking Klonopin for either panic disorder or seizure disorders. Examples of sexual side effects may include:

What you can do

If you experience sexual side effects from taking Klonopin, talk with your doctor. They may be able to recommend ways to manage these side effects. For example, your doctor may recommend taking Viagra (sildenafil) to treat erectile dysfunction caused by Klonopin.

If you have concerns about sexual side effects from taking Klonopin, talk with your doctor.

Allergic reaction

As with most drugs, Klonopin can cause an allergic reaction in some people. This rarely occurred in clinical trials of Klonopin.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Klonopin. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Before taking Klonopin, talk with your doctor about any medical conditions that you have. They can help determine whether Klonopin is safe for you to take.

This drug has boxed warnings about risk of misuse or addiction, physical withdrawal and dependence, and serious injury or death if taken with opioids. These are serious warnings from the Food and Drug Administration (FDA). For details, see the “Side effect specifics” section above.

Other precautions

Be sure to talk with your doctor about your health history before you take Klonopin. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Liver problems. Klonopin is broken down in your body by your liver. If your liver is not working well to break the drug down, it can build up in your body. Having too much Klonopin in your body can increase your risk of side effects or even overdose, which can be life threatening. So, if you have liver problems, your doctor may recommend a lower dose of Klonopin or more frequent monitoring while you are taking the drug.

Breathing problems. Tell your doctor if you have any breathing problems, such as chronic obstructive pulmonary disorder (COPD) or asthma. Klonopin can cause difficulty breathing or respiratory depression. If you have a breathing problem, taking this medication may worsen your condition. In this case, your doctor can help to determine whether Klonopin is a safe treatment option for you.

Glaucoma. It’s possible that Klonopin can increase symptoms of glaucoma. Sometimes, it is safe to take Klonopin if you have glaucoma. However, your doctor may recommend a different treatment option if you have glaucoma. Talk with your doctor to determine the best treatment plan for you.

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

Kidney problems. Klonopin exits your body through your kidneys. If your kidneys are not working properly, Klonopin can build up in your body. This can increase your risk of side effects, which in some cases, can be severe or life threatening. Due to this risk, your doctor may recommend a lower dose of Klonopin. Sometimes, they may recommend more frequent monitoring or a different treatment option for you.

Older adults. If you are an older adult (age 65 years or older), you may be at an increased risk of side effects from Klonopin. For example, older adults may have a higher risk of sleepiness, dizziness, or memory problems. Because of these risks, doctors may recommend that older adults take the lowest possible dose of Klonopin. They may also recommend more frequent monitoring for side effects of the drug.

Mood problems. Tell your doctor about any mood problems that you have before starting treatment with Klonopin. Rarely, Klonopin can increase your risk of mood problems, including depression or suicidal thoughts. If you have a mood problem, your doctor can help determine whether Klonopin may be safe for you.

Seizure disorders. Rarely, Klonopin can increase your risk of seizures. If you have a seizure disorder, taking Klonopin may make your condition worse. Talk with your doctor if you have a seizure disorder to see whether Klonopin may be a safe treatment option for you.

Porphyria. If you have a genetic condition called porphyria, tell your doctor before taking Klonopin. It’s possible for Klonopin to worsen porphyria symptoms, such as pain in the abdomen, chest, back, or legs. Your doctor can help determine whether Klonopin may be a safe option for you.

Alcohol with Klonopin

You should not drink alcohol while you are taking Klonopin. Drinking alcohol during your treatment with Klonopin can increase your risk of side effects which may be life threatening. These side effects can include:

  • dizziness
  • sleepiness
  • difficulty breathing
  • overdose
  • coma

Drinking alcohol while taking a benzodiazepine, such as Klonopin, can cause physical dependence and misuse.*

If you have questions about drinking alcohol while taking Klonopin, talk with your doctor.

* Klonopin has a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA). To learn more, see the “Klonopin and Misuse” section above.

Pregnancy and breastfeeding while taking Klonopin

It’s unknown if it’s safe to take Klonopin during pregnancy or what risks it may cause. It’s also unknown if it’s safe to breastfeed while taking Klonopin.

At this time, it’s not known if Klonopin may cause harm to a developing fetus. However, congenital anomalies (commonly known as birth defects) or developmental problems were reported in animal studies. It’s important to note that animal studies do not always indicate what may happen in humans.

In addition, if you take Klonopin during pregnancy, the baby may be born dependent on Klonopin, which can cause withdrawal symptoms, difficulty breathing, or trouble feeding.

There is a pregnancy registry available for people that take Klonopin during pregnancy. The purpose of a pregnancy registry is to collect information on a drug’s effects during pregnancy. This can help determine how safe a drug may be during pregnancy. To sign up for the registry, call 888-233-2334 or visit the webpage.

Klonopin use is not recommended while breastfeeding. The drug is known to pass into breast milk. However, it’s not known at this time what risks this may cause in children who are breastfed.

If you’re pregnant, planning to become pregnant, or breastfeeding, talk with your doctor to see whether Klonopin is safe for you.

Klonopin may cause side effects to occur. In most cases, side effects from this drug are mild. However, serious side effects of Klonopin are also possible.

If you’d like to learn more about Klonopin, talk with your doctor or pharmacist. They can help answer any questions you have about the drug’s side effects.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Klonopin. For details about other aspects of Klonopin, refer to this article.
  • Drug comparison. To learn how Klonopin compares with Xanax, read this article.
  • Dosage. For information about the dosage of Klonopin, view this article.
  • Interactions. To find out about Klonopin’s interactions, see this article.
  • A look at your condition. For details about panic disorder, visit our mental health hub. And to learn more about seizures, see our epilepsy and seizures hub.

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.