Klonopin is a well-known brand name for clonazepam, a drug most commonly used to help you calm down if you are having seizures or a panic attack. It is part of the class of drugs called benzodiazepines (street name “benzos”). It is the third most commonly prescribed benzodiazepine in the US, behind alprazolam (Xanax) and lorazepam (Ativan).
Commonly prescribed but frequently abused, Klonopin stays in the body for several days to weeks. On urine tests, Klonopin can often be detected for anywhere from 4 to 30 days after last use, with longer detection times in chronic or heavy users. Read on to learn more about Klonopin.
What Is Klonopin and How Does It Work?
As a form of clonazepam, Klonopin is a long-acting and high-potency benzodiazepine. It behaves as a GABA-A receptor agonist blocking the firing of neurons and thereby calming the brain. It also increases the production of serotonin, a neurotransmitter and a hormone, known for influencing mood, sleep, and digestion, and is often called the “feel-good” chemical.
Klonopin also has anticonvulsant and anti-anxiety effects and is FDA-approved for treating seizures and panic disorders. It has off-label use to treat mania, restless leg syndrome, insomnia, tardive dyskinesia (a movement disorder), and REM sleep behavior disorder [1].
Side effects of Klonopin are most commonly associated with lethargy, fatigue, sedation, drowsiness, and motor impairment (impaired coordination, impaired balance, dizziness).
Clonazepam is associated with an increased risk of depression, suicidal behavior, and thinking. So the patients and their caregivers should be cautioned to look for any symptoms of worsening of depression, changes in mood or behavior, or suicidal ideation.
Clonazepam and alcohol should not be taken together since both are CNS depressants. Their cumulative effect can result in sedation, severe respiratory depression, low blood pressure, and death.
While benzodiazepine prescribing has slightly declined in recent years due to increased awareness, it remains high. A study found that in the US, over 30 million adults, or 12.5% of the adult population (about the size of Texas) use benzodiazepines in a given year. A significant portion of this is long-term use for which it is not intended.
Klonopin Half-Life and Duration of Effects
Klonopin takes effect ~20-60 minutes after ingestion. The elimination half-life of Klonopin is around 30 to 40 hours (with a wide range of 18 to 50 hours). This is considered a very long half-life for a benzodiazepine. Noticeable effects last 8 to 12 hours for most people, but the active effects are much longer due to the long half-life.
Detection Times of Klonopin in Drug Tests
Tests for Klonopin vary as follows:
- Most Common Test (Urine): Detectable for 5 to 14 days after last use, and sometimes longer for chronic users [2].
- Blood: Detectable for 1 to 7 days.
- Saliva: Detectable for 5 to 6 days.
- Hair: Detectable for up to 90 days (or even longer).
Klonopin can be detected in urine for up to a month, in blood and saliva for about a week, and in hair for up to three months—sometimes longer.
Many factors affect the detection time, including:
- Frequency of Use
- Dosage
- Metabolism
- Age
- Body Mass and Hydration
- Liver and Kidney Function
- Other Medications
Note that a typical 5-panel or 10-panel urine test (common for employment) does not specifically test for Klonopin. However, these standard tests almost always include a general “Benzodiazepines” category. Klonopin will trigger a positive result on this general benzodiazepine immunoassay test.
Risks of Klonopin Dependence and Withdrawal
Because it’s a long-acting benzodiazepine, Klonopin poses a high risk for dependence and withdrawal. This is so even when used as prescribed. Risks increase the longer you use it and with higher doses.
Risks of Dependence with Klonopin
Physical and psychological dependence can develop quickly. As the body adapts to Klonopin, higher doses are required for the same effect. This is called tolerance. This can then escalate the cycle of use and increase the risk for addiction [3].
Chronic use may result in:
- Ongoing cognitive impairment
- Coordination problems
- Memory disturbance
- Worsening mental health
- Depression
- Suicidality
If you combine Klonopin with opioids, alcohol, or other CNS depressants, you greatly increase the risk of fatal overdose due to severe respiratory depression or coma.
Risk factors for developing dependence include a personal or family history of substance use, co-occurring mental health conditions, and young age.
Withdrawal Risks and Symptoms
Stopping Klonopin suddenly can provoke acute withdrawal reactions, which may be life-threatening. Symptoms may include [1]:
- Anxiety
- Panic attacks
- Agitation
- Tremors
- Seizures
- Insomnia
- Psychosis
- Suicidal thoughts
Withdrawal usually occurs in two stages: acute withdrawal with severe anxiety, sleep problems, and seizures, and protracted withdrawal, with symptoms lasting for weeks to months.
Because of these risks, withdrawal should be medically supervised and usually involves a slow taper lowering the dose over weeks or even months. In rare cases, Klonapin withdrawal can result in protracted symptoms lasting over a year.
Even individuals who have taken the drug as prescribed can experience withdrawal symptoms and should not discontinue without medical supervision.
Benzodiazepine Addiction Treatment at Northbound
Nearly 95% of people who sought benzo addiction treatment also abused another substance in addition to benzodiazepines. So polydrug use is a big issue for the individual and in treatment. As well, if there are underlying co-occurring mental health conditions, the addiction can be harder to treat.
At Northbound, we have extensive experience helping patients overcome their substance abuse addictions, including benzos.
The first steps are detoxification and stabilization, under 24-hour medical supervision in our Withdrawal Management center for whatever time you may require.
We offer a wide range of evidence-based therapies, counseling, and trauma-informed support to assist you in your healing. We personalize each treatment plan around the needs of our patients.
Our inpatient residential program offers 24/7 live-in treatment for substance abuse. Our outpatient treatment provides a flexible step-down from our residential program allowing you to live at home and participate for several hours a day.
For more than 30 years, Northbound Treatment Services in California has been at the forefront of providing lifesaving, compassionate residential care and specialized services to help people from all walks of life feel better, discover themselves, and live free from addiction.
We have facilities located throughout California to help guide you on your recovery journey. Reach out to our admissions team now.
Sources
[1] Basit H, Kahwaji C. Clonazepam.[Updated 2023 May 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-
[2] Nordal K. et al. Detection Times of Diazepam, Clonazepam, and Alprazolam in Oral Fluid Collected From Patients Admitted to Detoxification, After High and Repeated Drug Intake. Ther Drug Monit. 2015 Aug;37(4):451-60.
[3] Clonazepam Abuse Symptoms and Addiction Treatment. 2025. DrugAbuse.com
Author
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I am a Licensed Clinical Social Worker and graduated with a degree from the USC School of Social Work in 2015 with an emphasis in mental health. I began my career working with the Orange County Welfare to Work Program providing mental health services to reduce barriers to employment. I have spent the last 5 years working various levels in behavioral health, providing direct service to those struggling with co-occurring disorders. Using an eclectic and integrative approach, I incorporate the AIP model with EMDR, Person-in-Environment (PIE), Motivational Interviewing (MI), Cognitive Behavioral Therapy (CBT), Dialectical Behavioral Therapy (DBT), family systems, interpersonal and solution-focused therapy along with Rogerian positive regard into my practice.
