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How Long Does It Take for Klonopin to Kick In?

In most use cases, Klonopin should take about 1 to 4 hours to take full effect if taken as prescribed. 

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You should never take more of your medication or take it in a different way than intended by your doctor to try to speed up this process. Doing so can increase your risk of complications and may cause the medication to work differently than intended.

Basics of Klonopin

Klonopin is a brand name for the drug clonazepam, a benzodiazepine. These drugs act on a certain neurotransmitter in the brain and can help to calm abnormal activity. 

Klonopin has an elimination half-life of about 30 to 40 hours, which is how long it takes the body to eliminate around 50 percent of the drug. Within about four to five half-lives, or 120 to 200 hours, you can expect at least 95 percent of the drug to be eliminated from a human body, assuming the body is able to process the drug normally.

Klonopin is often called a long-acting benzodiazepine but in reality, the term intermediate-acting is arguably more accurate. 

Dosing varies, but patients are typically started on a small dose taken two times a day, with their dose raised if the drug doesn’t have the desired effect. In some cases, it can take a few days to a few weeks for Klonopin to fully take effect depending on why it’s being used, such as if it is used to reduce seizures. 

When possible, it is only prescribed in the short term, as long-term use can cause a person to develop physical dependence and increase the risk of engaging in drug misuse or becoming addicted to the drug.

How Long Does It Take for Klonopin to Peak?

Taken as prescribed, Klonopin will reach its peak concentrations in the blood within 1 to 4 hours. The drug is what is called “highly metabolized,” which means most of it will be processed by the body. Very little of it will leave the body unchanged, with as little as 2 percent of Klonopin being excreted in the urine unmetabolized. 

Factors That Impact Absorption

The method by which a drug is taken can significantly impact the speed of absorption. 

Klonopin is generally taken orally, which is one of the slowest paths of absorption. Note that “slow” doesn’t mean ineffective. It is deliberately prescribed orally to produce the best results in users who take it as prescribed. 

If the drug is instead snorted, as some people who misuse the medication take it, absorption will be faster. This is generally done to produce a more intense effect, resulting in a sedative “high.” This type of drug misuse can be dangerous, increasing one’s risk for various complications, including significant respiratory depression, drug dependence, and drug addiction.

Some health conditions can also affect drug absorption, such as some GI diseases, as can some drugs. This is why it’s important to talk openly with your doctor about your health and any drugs you’re taking when being prescribed any medication. The doctor needs to have an accurate understanding of how your body is likely to react to your medication and if any dangerous interactions might occur.

Klonopin Dosages

Klonopin dosages will depend on why the drug is being taken and can be highly variable among children, as their bodies are more varied than those of adults. Typical doses include the following:

  • 1 mg taken at night, increasing to 4 mg to 8 mg over 2 to 4 weeks, for adults who have epilepsy
  • 1 mg taken at night, increasing to 4 mg to 8 mg over 2 to 4 weeks, for adults who have involuntary muscle spasms
  • 1 mg to 2 mg each day for those with panic disorders
  • 500 micrograms to 2 mg each day for those with restless legs syndrome
  • Significantly varied dosing for children with epilepsy, with a similar gradual increase in dose over 2 to 4 weeks as with adults
Updated May 1, 2023
  1. Clonazepam. (January 2020). NHS.
  2. Clonazepam (Klonopin). (September 2021). National Alliance on Mental Illness.
  3. KLONOPIN TABLETS (clonazepam). (October 2013). U.S. Food and Drug Administration.
  4. Snorted, Injected or Smoked? It Can Affect a Drug’s Addictiveness. (September 2015). The Conversation US, Inc.
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