Tizanidine Half-Life: Zanaflex In Body System

Last Updated: February 19, 2020

Zanaflex half-life refers to the time needed by the drug’s concentration in the plasma to be reduced by a percentage of 50%. After the half-life of Zanaflex takes place, the drug’s level in the system will be only half of the initial dose.

Tizanidine Half-Life

After administering either a tablet or a capsule of tizanidine, the peak plasma concentrations of the drug take place one hour after ingestion. The half-life of tizanidine is about two hours to two hours and a half. Almost 95% of a dose is metabolized. The metabolites of tizanidine are not known to be active, with a half-life varying between 20 and 40 hours.

In fasting conditions, the peak plasma concentration is one hour after ingestion and half-life of around two hours. When administered with food, the plasma concentration raises by 30% to one hour and 25 minutes.

How Long Does Zanaflex Stay In Urine?

A single tizanidine dose of 4 mg can be detected in urine from 5 to 13 days after taking a single dose. A urine drug test or urine drug screen is used to check for both prescription and illegal drugs, and it is the most common method of drug testing.

How Long Does Zanaflex Stay In Blood?

A blood test is usually requested when the individual is suspected to be under the influence of a drug. When taken from the blood, Zanaflex drug testing can detect the medication from two hours after ingestion to up to 10 days.

How Long Does Zanaflex Stay In Hair?

Tizanidine can be detected in hair, and this type of test is perfect for determining the long-term exposure to this drug, depending on the individual’s hair length. Tizanidine can be detected in hair only a few days after use.

woman looking at her hair

How Long Does Zanaflex Stay In Saliva?

Tizanidine can be detected in oral secretions for 24 to 48 hours after the last use.

Does Zanaflex Show Up On a 12 Panel Drug Test?

Tizanidine is not a controlled drug. Therefore it will not appear on a 12-panel drug test. Zanaflex 12 panel drug test can turn positive if it is done to detect this medication.

Usually, the 12-panel drug test is used to test for marijuana, cocaine, PCP, benzodiazepines, opiates, methadone, amphetamines, Quaaludes, barbiturates, Ecstasy/MDA, propoxyphene, and Oxycodone/Percocet.

Variables That Affect How Long Zanaflex Stays In The System

Although the half-life of Zanaflex is around two and a half hours, how long it stays in the system varies from one person to another and depends on several factors and variables, which influence this period. The doctor should explain to the patient the Tizanidine mechanism of action, as well as factors that play an important role in the drug’s presence in the body.

Such factors are:

  • Age
  • Dosage
  • Metabolism rate
  • Quality of the medication (some people try to avoid the high tizanidine cost in the drug stores by purchasing the medication online or on the streets but of poor quality)
  • Body mass and weight
  • Food intake
  • Co-administered drugs, such as combining tizanidine and Flexeril together
  • Water amount in the system
  • How the medication was used
  • Kidney and liver health
  • Frequency of administration

How To Remove Zanaflex From System Faster

Knowing what tizanidine is and what its mechanism of action is, can help the user understand how the medication works. For those who worry about a Zanaflex drug test, there are several things that they can do to help the medication be eliminated from the system faster.

elderly patient talking to a nurse about medication

Calcium D Glucarate

This supplement is said to have detoxifying properties, clearing out the kidneys’ pathways. As most of the tizanidine is excreted by the kidneys and cleared out through urine, it would make sense that this supplement would help to rid the system from tizanidine faster.

Activated charcoal

Activated charcoal is sometimes successfully used to treat poisoning or a drug overdose. Toxins and drugs bind to activated charcoal, helping to clean the body.


Although drinking water and other liquids will not significantly speed up the elimination of tizanidine from the body, it can still offer some benefit. Liquid makes the clearance of drugs faster through urine. It should be noted that drinking too much water can be toxic and do more harm than good. Also, hydration might help with some of the Zanaflex side effects such as dry mouth and constipation.


People that have highly alkaline urine might reabsorb the medication before it is excreted.

. To avoid this, keep the urine at a close to neutral pH by avoiding red meat, cranberry and orange juice, alcohol, and coffee.

Find The Help One Needs

Knowing the half-life of tizanidine can help in a possible tizanidine drug test, but also helps the individual to avoid any possible unpleasant withdrawal symptoms if the medication is quit cold turkey. That is why it is important to talk to your doctor or a specialist from a recovery facility regarding any concerns about a possible dependence on this drug. The doctor might consider replacing the medication with another one. For example, when comparing methocarbamol vs. tizanidine, the first one proved to be less sedating and with fewer side effects.

Any individual can access effective treatment for addiction to drugs in specialized facilities all over the country.

Page Sources

  1. PRESCRIBING INFORMATION. Zanaflex Capsules. U.S. Food And Drug Administration. https://www.accessdata.fda.gov/drugsatfda_docs/label/2006/020397s021,021447s002lbl.pdf
  2. Sheykhaghaei G, Hossainisadr M, Khanahmadzadeh S, Seyedsajadi M, Alipouramjad A. Magnetic molecularly imprinted polymer nanoparticles for selective solid phase extraction and pre-concentration of Tizanidine in human urine. J Chromatogr B Analyt Technol Biomed Life Sci. 2016. https://www.ncbi.nlm.nih.gov/pubmed/26744788

Published on: February 19th, 2020

Updated on: February 19th, 2020


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