Clonazepam vs. Lorazepam: Key Differences Between Klonopin and Ativan
Author:
Blossom Editorial
Clonazepam (Klonopin) and lorazepam (Ativan) are both benzodiazepines, a class of medications that calm the nervous system. Both can treat anxiety, panic, and certain other conditions, and they also work in similar ways. But they differ in how quickly they take effect, how long they last, how the body processes them, and what they're approved to treat. Understanding these differences can help you have a more informed conversation with your prescriber.
Key Takeaways
Both are commonly prescribed: Of roughly 92 million benzodiazepine prescriptions dispensed in the U.S. in 2019, about 24% were for clonazepam and 20% for lorazepam.
The biggest difference is duration: Clonazepam has a half-life of about 30 to 40 hours, while lorazepam's is about 12 hours. As a result, clonazepam tends to provide steadier, longer coverage, while lorazepam is often used for shorter-term relief.
Both carry serious risks: Benzodiazepines can cause physical dependence and withdrawal. Taking them as prescribed, avoiding alcohol or opioids, and working with your prescriber before stopping can help reduce these risks.
What Is the Difference Between Clonazepam and Lorazepam?
Clonazepam and lorazepam work in similar ways, but they were developed and approved for different primary uses. Here's a closer look at each medication.
What is Clonazepam (Klonopin)?
Clonazepam is a long-acting benzodiazepine sold under the brand name Klonopin. It's FDA-approved to treat panic disorder, with or without agoraphobia, and certain seizure disorders. It's available as tablets and orally disintegrating tablets. Because it lasts a long time in the body, it's often taken once or twice a day on a regular schedule.
What is Lorazepam (Ativan)?
Lorazepam is a shorter-acting benzodiazepine sold under the brand name Ativan. Its oral tablets are FDA-approved for the management of anxiety disorders and short-term relief of anxiety symptoms, including anxiety associated with depressive symptoms. An injectable form is also used in hospitals, for example, to control prolonged seizures or for sedation before certain procedures.
Clonazepam vs Lorazepam at a Glance
The table below summarizes some key differences between clonazepam and lorazepam.
Feature | Clonazepam (Klonopin) | Lorazepam (Ativan) |
|---|---|---|
FDA-approved oral uses | Panic disorder, certain seizure disorders | Anxiety disorders, short-term anxiety relief |
Time to peak blood levels | 1 to 4 hours | About 2 hours |
Half-life | About 30 to 40 hours | About 12 hours |
How the body processes it | Broken down by the liver | Converted to an inactive form and removed by the kidneys |
Typical dosing pattern | Once or twice daily | Two to three times daily or as prescribed |
Controlled substance | Yes (Schedule IV) | Yes (Schedule IV) |
How Common Are Clonazepam and Lorazepam Prescriptions?
Benzodiazepines are among the most commonly prescribed psychiatric medications in the U.S. Federal data show that an estimated 92 million benzodiazepine prescriptions were dispensed in 2019, with clonazepam and lorazepam among the top three. Although benzodiazepines are often recommended for short-term use, some people also take them for longer periods.
However, the FDA labels clearly state that the effectiveness of both clonazepam (Klonopin) and lorazepam (Ativan) have not been studied for more than 9 weeks and 4 months, respectively. Long-term use must be periodically evaluated by the prescriber.
How Do Clonazepam and Lorazepam Work?
Both medications can enhance the effects of gamma-aminobutyric acid (GABA), a natural brain chemical that slows nerve activity. By strengthening GABA's calming effects, benzodiazepines can reduce anxiety, relax muscles, promote sleep, and prevent seizures. The main differences between clonazepam and lorazepam come down to how quickly they're absorbed and how long they stay active.
Onset and Duration: How Fast and How Long They Work
Timing is an important difference between these two medications. Both start working relatively quickly, but clonazepam generally stays active in the body much longer than lorazepam.
How Fast They Work
Lorazepam reaches peak levels in the blood about 2 hours after a dose, and some people may feel its calming effects sooner. Clonazepam reaches peak levels within 1 to 4 hours, so its onset can be a bit more gradual.
How Long They Last
Clonazepam's half-life is about 30 to 40 hours, compared with about 12 hours for lorazepam. This means it stays in the body much longer than lorazepam and may provide sustained effects between doses. Lorazepam's shorter duration can be useful for situational anxiety, but some people may notice anxiety returning between doses.
Which Is Better for Anxiety and Panic?
Neither medication is better for everyone. The right choice depends on the type of anxiety, how often symptoms occur, your medical history, and how you respond to treatment.
Panic Disorder
Clonazepam is FDA-approved for panic disorder. In clinical trials with a 6-week optimal dose phase and 6-week discontinuance phase, 62% of people taking clonazepam had no full panic attacks by the end of treatment, compared with 37% of people on placebo. Its long duration of action may help provide more sustained symptom control.
General and Situational Anxiety
Lorazepam is approved for anxiety disorders and short-term relief of anxiety symptoms. Its faster peak and shorter duration can make it useful for specific stressful situations or for brief periods of severe anxiety. It may also be prescribed for short-term symptom relief while a longer-term treatment, such as an antidepressant, begins to work.
Liver Health and Other Factors
Because lorazepam is converted into an inactive form that's removed through the urine, it may be preferred for some people with liver problems. Clonazepam is broken down by the liver, and its prescribing information advises caution in people with liver disease.
Clonazepam vs Lorazepam Side Effects
Because clonazepam and lorazepam belong to the same drug class, they share many potential side effects. Common side effects include:
Drowsiness or sleepiness
Dizziness
Poor coordination or unsteadiness
Slowed thinking or trouble concentrating
Memory problems
Fatigue or weakness
Side effects from clonazepam may last longer into the next day because of its long half-life, while lorazepam's effects tend to wear off sooner.
Risks and Safety Warnings
Both medications carry serious risks associated with benzodiazepines. Key safety considerations include:
Dependence and withdrawal: The FDA requires a boxed warning on all benzodiazepines about abuse, misuse, addiction, physical dependence, and withdrawal reactions. Physical dependence can develop even when you take these medications as prescribed.
Opioids: Combining benzodiazepines with opioids can cause profound sedation, slowed breathing, coma, or death. This combination is generally avoided unless no suitable alternatives are available.
Alcohol: Mixing benzodiazepines with alcohol can intensify drowsiness and slow breathing.
Older adults: Benzodiazepines are linked to a higher risk of falls in older adults. Research suggests this risk applies to both short-acting and long-acting benzodiazepines, including findings from studies of older adults hospitalized after falls.
Driving and machinery: Both medications can impair alertness and reaction time.
Pregnancy: Benzodiazepines may affect a developing baby. Discuss pregnancy, plans to become pregnant, or breastfeeding with your prescriber before using either medication.
Stopping Clonazepam or Lorazepam Safely
Physical dependence can develop when benzodiazepines are taken regularly for several days to weeks, even at prescribed doses. Stopping suddenly or lowering the dose too quickly can cause withdrawal reactions, including seizures, which can be life-threatening.
To stop either medication, prescribers typically recommend a gradual taper tailored to your dose and how long you've been taking it. Lorazepam's shorter half-life may make withdrawal symptoms appear more quickly after a missed dose, while clonazepam's longer half-life tends to make levels decline more slowly.
Alternatives to Benzodiazepines for Anxiety
Benzodiazepines are usually recommended for short-term use because of the risks of dependence and withdrawal. For longer-term anxiety treatment, prescribers may consider other medications or therapy, depending on your symptoms and needs:
Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs): Antidepressants like escitalopram, sertraline, and venlafaxine are common long-term treatments for anxiety.
Buspirone: This medication is approved for generalized anxiety disorder (GAD) and has a lower risk of physical dependence than benzodiazepines.
Other medications: Options such as hydroxyzine may help some people manage anxiety. You can read our review on how hydroxyzine compares with alprazolam (Xanax), another commonly prescribed benzodiazepine.
Propranolol: May help physical symptoms of performance anxiety, and it's important to understand how quickly propranolol works for anxiety when timing a dose.
Therapy: Cognitive behavioral therapy (CBT) is an evidence-based treatment for anxiety and panic disorder.
When to Seek Medical Attention
Some symptoms require immediate medical attention. Call 911 or go to the nearest emergency room if you or someone else has extreme drowsiness, confusion, slowed or difficult breathing, bluish lips, or difficulty waking up, especially after combining a benzodiazepine with alcohol or opioids.
Contact your prescriber if you notice worsening depression, memory problems, or signs of withdrawal such as tremors, severe anxiety, or trouble sleeping. If you're struggling with misuse, SAMHSA's National Helpline at 1-800-662-4357 offers free, confidential support. If you have thoughts of suicide, call or text 988.
How Blossom Health Can Help
Choosing between anxiety medications, or deciding whether a benzodiazepine is appropriate for you at all, can be easier with professional guidance. Blossom Health connects you with board-certified psychiatric providers for virtual care. Providers can evaluate your symptoms, discuss short-term and long-term options, and create a treatment plan that fits your needs. Prescribing controlled medications like clonazepam and lorazepam follows federal and state rules, so your provider can explain which options may be available to you.
Blossom works with many insurance plans, so you can check your coverage and get started with Blossom Health.
Medical Disclaimer
This article is for informational purposes only and is not a substitute for professional medical advice. If you are in crisis or thinking about harming yourself, call or text 988 or call 911.
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