How Long Does Tizanidine Stay in Your System?
Key takeaways:
Tizanidine (Zanaflex) is a muscle relaxer that's prescribed to treat muscle spasticity. Tizanidine’s half-life is about 2.5 hours. It typically stays in the body for about 10 to 12 hours. However, its effects only last about 3 to 6 hours.
Exactly how long tizanidine stays in your system depends on several factors, including what other medications you take, your age, and your kidney and liver health.
There are some situations in which you may need a lower dosage of tizanidine. Or you may need to avoid it entirely if you take certain medications.
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Table of contents
Tizanidine (Zanaflex) is a muscle relaxer that’s prescribed to relieve muscle spasticity, a condition that causes tight, stiff muscles. It’s available as tablets or capsules, which may be taken up to 3 times a day.
Tizanidine stays in your system for about half a day. But that doesn’t mean it’s actually effective for that long. Read on to learn more about how long tizanidine stays in your system and what factors affect how long it takes for the muscle relaxer to wear off.
How long does tizanidine stay in your system?
Tizanidine stays in your system for about 10 to 12 hours after taking a dose.
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How long a medication stays in your body is determined by its half-life. A half-life is the estimated time it takes for half the amount of a medication’s total concentration to be removed by the body. It generally takes about four to five half-lives for the body to clear a medication.
Tizanadine’s half-life is 2.5 hours. That’s why it takes about 10 to 12 hours for your body to completely clear a dose. This doesn’t mean that a dose of tizanidine is effective for 10 to 12 hours. The effects of tizanidine typically wear off between 3 to 6 hours after taking a dose. That’s why it’s typically taken every 6 to 8 hours.
Can you flush tizanidine out of your system?
No, you can’t flush tizanidine out of your system by drinking more fluids or with other means. For tizanidine to leave your body, a portion of it needs to be metabolized (broken down) first. As mentioned above, this process can take about 10 to 12 hours.
Are there factors that can affect how long tizanidine stays in your system?
Yes, several factors can affect how long tizanidine stays in your system. We cover four of those factors below.
1. Drug interactions
Certain medications can interact with tizanidine and block it from being metabolized. This increases the amount of time tizanidine stays in your system. Some notable medications that can interact with tizanidine include:
Fluvoxamine (Luvox): Taking the antidepressant fluvoxamine with tizanidine can increase the muscle relaxer’s half-life. It can take your body up to three times longer to completely clear tizanidine if you take it with fluvoxamine.
Ciprofloxacin (Cipro): The antibiotic ciprofloxacin can cause tizanidine to stay in your system longer. It can also cause tizanidine levels to spike in the body.
Birth control pills: Birth control pills, especially those containing ethinyl estradiol or desogestrel, can block tizanidine from being metabolized. Examples include Sprintec and Ortho Tri-Cyclen 21, which contain ethinyl estradiol and norgestimate, and Apri, Kariva, and Viorele, which all contain desogestrel and ethinyl estradiol. By causing tizanidine to build up in the body, these birth control pills can increase the risk of side effects from the muscle relaxer.
As with other muscle relaxers, no amount of alcohol is considered safe to consume while tizanidine is in your system. For one thing, alcohol and tizanidine both cause sedation. And while alcohol doesn’t necessarily increase how long tizanidine stays in your body, it may increase blood levels of the medication. Though, more research is needed to understand this interaction.
Taking tizanidine with alcohol or any of the above medications can increase your risk of side effects from the muscle relaxer. Examples of possible side effects include drowsiness, low blood pressure, and trouble with coordination.
It can be difficult to keep track of which medications can affect tizanidine metabolism. So it’s a good idea to provide your healthcare team with a list of your current medications before you start taking the muscle relaxer. If drug interactions are possible, your prescriber may decrease your tizanidine dosage or recommend changes to your medication regimen.
Tizanidine drug interactions: Some medications can affect how long tizanidine stays in your body. Other medications increase the risk of side effects.
Tizanidine dosage guide. Learn about the typical starting dosage of tizanidine, which is usually taken every 6 to 8 hours.
What else should you know about tizanidine? Before you start taking tizanidine, it’s helpful to know what side effects to watch for. Learn about notable tizanidine side effects and how to manage them.
2. Kidney function
Tizanidine is cleared by the kidneys. So how well your kidneys work can affect how long tizanidine stays in your system. In fact, it may take twice as long to completely clear tizanidine from your body if you have severe kidney problems. This increases your risk of side effects from the medication.
Your healthcare professional will consider your kidney health before prescribing you tizanidine. If you have kidney problems, they may prescribe you a lower tizanidine dosage.
3. Liver function
It hasn’t been well studied whether having liver problems can make tizanidine last longer in the body. But since tizanidine is metabolized by the liver, it’s expected that this would be the case. If so, this would increase your risk of tizanidine side effects.
Let your prescriber know if you have any type of liver disease before starting treatment with tizanidine. They may start you with a lower dosage of the muscle relaxer.
4. Age
Age can affect how long it takes the body to clear tizanidine. Specifically, adults age 65 and older are more likely to have reduced liver and kidney function, which can cause the medication to stay in the body longer.
Depending on your age, your prescriber may start you with a lower tizanidine dosage.
Considerations for how long tizanidine stays in your system
There are certain situations in which it’s especially important to consider how long tizanidine stays in your system — for example, if you’re planning a pregnancy or stopping treatment. Below, we discuss these situations in detail.
Drug interactions
As mentioned above, several medications can increase tizanidine levels in the body. This can make tizanidine last longer in your system and increase your risk of side effects.
Before you start taking tizanidine, or before starting any new medications while taking tizanidine, talk to your prescriber and pharmacist about possible drug interactions. If you’re at risk of experiencing an interaction, they may adjust your medication regimen. This may include instructing you to wait a certain amount of time between taking tizanidine and an interacting medication.
Pregnant or breastfeeding
Based on animal studies, tizanidine may cause harm to an unborn fetus. Although results from animal studies can’t be applied directly to humans, healthcare professionals are still cautious when prescribing tizanidine during pregnancy. The same goes for prescribing tizanidine to someone who is breastfeeding.
Tell your prescriber if you become pregnant or plan on becoming pregnant while taking tizanidine. They’ll help you decide whether it’s safe to continue taking the medication.
Side effects
Tizanidine may cause mild side effects such as drowsiness, dizziness, and dry mouth. Though rare, it’s also possible to experience more severe side effects from the medication. Examples include liver problems, hallucinations, and severe allergic reactions.
If you experience side effects from tizanidine, let your prescriber know. They may recommend that you stop taking the medication.
In most cases, tizanidine side effects should go away soon after you stop taking it. But if you have a condition that increases how long tizanidine stays in your system, it may take longer for the side effects to go away.
Keep in mind that stopping treatment tizanidine too quickly can lead to withdrawal symptoms such as increased blood pressure, muscle tightness, and rapid heartbeat. To prevent this from happening, your prescriber may decrease your dosage gradually when it’s time to stop taking tizanidine.
The bottom line
Tizanidine (Zanaflex) is a muscle relaxer that’s prescribed to help relieve muscle spasticity. After you take a dose of tizanidine, it generally takes about 10 to 12 hours for your system to clear the medication. However, the effects of a tizanidine only last about 3 to 6 hours.
Exactly how long tizanidine stays in your system depends on several factors. These include your age, your kidney and liver health, and what other medications you take.
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References
Granfors, M. T., et al. (2004). Ciprofloxacin greatly increases concentrations and hypotensive effect of tizanidine by inhibiting its cytochrome P450 1A2-mediated presystemic metabolism. Clinical Pharmacology and Therapeutics.
Granfors, M. T., et al. (2004). Fluvoxamine drastically increases concentrations and effects of tizanidine: A potentially hazardous interaction. Clinical Pharmacology and Therapeutics.
Granfors, M. T., et al. (2005). Oral contraceptives containing ethinyl estradiol and gestodene markedly increase plasma concentrations and effects of tizanidine by inhibiting cytochrome P450 1A2. Clinical Pharmacology and Therapeutics.
Morgom, M., et al. (2023). A case of tizanidine withdrawal syndrome: Features and management in the emergency department. Cureus.
PD-Rx Pharmaceuticals. (2019). Tizanidine - tizanidine tablet [package insert].
Preferred Pharmaceuticals. (2023). Tizanidine hydrochloride - tizanidine hydrochloride capsule [package insert].
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