Tizanidine (brand name: Zanaflex) is a centrally acting muscle relaxant. It works by blocking nerve impulses in your spinal cord. That way, it helps relax muscles and reduces cramping.
The drug is more popular than ever before. Between 2007 and 2017, there was a six-fold increase in the number of prescriptions. Prescriptions soared from 1.54 million in 2007 to over 9 million in 2017.1
In 2017, tizanidine ranked 89th in the list of most commonly prescribed drugs in the US, up from 118 in the previous year.1 The trend will likely continue in the coming years. Experts predict the global muscle relaxant market will increase to over $2.7 billion by 2025 from $1.7 billion in 2018.2
Tizanidine is a member of a group of medicines called alpha-2-adrenergic agonists. Alpha-2-adrenergic agonists cause sedation, relieve pain, and reduce blood pressure.
Some drugs in this class, such as tizanidine, relax skeletal muscles. That is why tizanidine is known as a muscle relaxant or muscle relaxer.
Alpha-2-adrenergic agonists are used in a variety of conditions, including:3
High blood pressure
Attention-deficit/hyperactivity disorder (ADHD)
Attention-deficit disorder (ADD)
Other drugs in the class are:
No street names have been reported. It might be because the drug is not as popular among users as other prescription medicines like opioids and stimulants. Moreover, a lack of street names also suggests that the drug might not have reached the street market. According to streetRx, the street value of a 4 mg pill ranges from $1 to $15.4
Two formulations of tizanidine are available – oral tablets (2, 4 mg) and capsules (2, 4, and 6 mg). You may take the tablets or capsules with or without food.
If you take tablets with food, continue taking them with foods, but never switch to capsules or take them without food. You should never change the regimen without consulting your doctor.
Read the prescription label carefully and follow the directions there. If you have any questions, ask your doctor or pharmacist. Always use the drug only as directed. Do not increase or decrease the dose or frequency without asking your doctor.
Your body absorbs tizanidine from the tablets and capsules differently. Therefore, you should not substitute one formulation with the other.
Your doctor may prescribe the drug for conditions other than approved by the FDA. Talk with your doctor or pharmacist to learn more.
The drug is as effective as baclofen and diazepam in the treatment of spasticity. It is less likely to cause muscle weakness than baclofen and is less sedating compared to diazepam.
Since it received US FDA approval in 1996, the drug has helped millions of people with muscle spasms associated with medical conditions, such as multiple sclerosis, spinal injuries, and traumatic brain injuries.
One study shows that tizanidine helps improve muscle tone in up to 80% of users.5 People using Zanaflex also tend to experience fewer side effects than those taking baclofen.
Moreover, the drug is effective in relieving chronic neck pain. People who have pain due to damaged nerves (neuralgia) may also benefit from tizanidine. Notably, in these people, it may be as effective as another popular drug – clonidine.
Apart from the FDA-approved uses, tizanidine also has several “off-label” uses. A doctor may prescribe it off-label to treat migraines, seizures, and sleep problems.
No medicine is 100% safe; all of them carry a risk of side effects. That said, some drugs are inherently more likely to cause severe side effects than others are. Likewise, some may be habit-forming. Because tizanidine acts on the spinal cord, some people think it might be addictive.
According to researchers at Nova Southeastern University, tizanidine is one of the top 12 non-controlled drugs with a high risk of addiction. Other muscle relaxants on the list include cyclobenzaprine and methocarbamol.6
Most drugs that act on the brain and the spinal cord can cause undesirable symptoms when you stop taking them. These are known as withdrawal symptoms. Nonetheless, withdrawal alone does not make a substance addictive. Withdrawal is a component of addiction, which also comprises dependence and drug-seeking behavior.
There have been no documented cases of tizanidine addiction. However, some people who develop severe withdrawal may need treatment to prevent complications.
Tizanidine is not narcotic. Narcotics, also called opioids, are powerful pain relievers. Doctors prescribe them to treat moderate-to-severe pain. They block pain signals in the brain. Examples of opioids are codeine, morphine, fentanyl, oxycodone, and tramadol.
Unlike tizanidine, narcotic painkillers have high abuse potential. For this reason, the Drug Enforcement Administration (DEA) controls them. Examples of scheduled narcotic drugs are:
Tylenol with Codeine, and buprenorphine (Schedule III)
Tizanidine is not a controlled substance. That means the drug does not appear in any of the five schedules. The DEA, under the Controlled Substances Act (CSA), categorizes drugs into different schedules based on the drug’s abuse potential.
For example, Schedule I substances have high abuse potential and no medical use. They are highly addictive and cause severe dependence. Examples include heroin, lysergic acid diethylamide (LSD), and ecstasy. Likewise, Schedule V drugs have the least abuse potential. They are less likely than other scheduled drugs to cause dependence. Examples include Lomotil, Motofen, Lyrica, and Parepectolin.
Due to the lack of strong evidence showing high abuse potential, the DEA has not classified tizanidine into any of the schedules. Nonetheless, DEA scheduling is a dynamic process. Depending on the evidence, substances may be rescheduled or included in a schedule.
Any drug that has received FDA approval is considered safe. The FDA allows a drug product to be marketed only after it has passed several tests. Researchers conduct these tests in the laboratory, in animals, and then in human participants.
Moreover, a drug’s safety is evaluated years after it has become available in the market. It is known as post-marketing surveillance (PMS). PMS helps identify unwanted effects that may not have appeared during routine tests.
A drug may be withdrawn from the market years after an FDA approval. For example, Merck & Co. voluntarily withdrew its blockbuster drug Vioxx (rofecoxib) in 2004. The FDA had approved Vioxx for treating osteoarthritis in 1999.
So far, there have been no reports of potentially fatal effects of tizanidine. According to the FDA, it has not identified any new safety concerns other than those found in routine tests. Thus, the drug is safe as long as you take it as prescribed.
Tizanidine has a narrow therapeutic index (TI). It means there is not much difference between the recommended and toxic doses. Thus, it is critically important to take the drug only in the recommended doses.
The other safety warnings are:
Low blood pressure is a well-established side effect. Reduced blood pressure may lead to extreme dizziness, drowsiness, or fainting. Therefore, your doctor may start the treatment with the lowest effective dose. Then, they may gradually increase the dose depending on your response.
Tell your doctor if you take blood pressure-lowering medications, such as water pills, captopril (Capoten), candesartan (Atacand), and others.
5 in 100 people taking the drug have high levels of a liver enzyme – alanine aminotransferase (ALT).7 Elevated ALT level is temporary and often does not produce any symptoms. Nonetheless, tizanidine may cause liver injury severe enough to cause death.
Talk with your doctor if you have a liver disorder. Your doctor may change the doses or prescribe another drug.
People who take tizanidine have reported seeing things that are not there (visual hallucinations). Besides, some users may have delusions (a firm but false belief). Talk to your doctor immediately if you experience any of these effects.
There is limited information about the effects of tizanidine on the fetus. So, use during pregnancy is not usually recommended.
A doctor may prescribe the drug if benefits clearly outweigh the potential risks to the unborn baby. Talk to your doctor if you:
Are pregnant (before starting the drug)
Become pregnant during treatment
Plan to become pregnant while on the medication
Tizanidine is soluble in fat and can pass into mother’s milk. Ask your doctor if you can breastfeed while taking the drug.
You will start experiencing the intended effects within 2 hours after you take a 2 mg capsule. The effects wear off about 4.5 hours post-dose. Thus, your doctor may ask you to repeat the doses every 6 to 8 hours. The maximum daily-recommended dose is 36 mg.
Side effects are undesirable effects that occur at recommended doses. Many of them can be mild and self-limiting. However, some side effects are severe and need immediate medical attention. Serious side effects are common if you take the drug with alcohol or other drugs.
The following short-term side effects are usually mild, and do not require immediate medical attention:
Loss of appetite
Talk to your doctor immediately if you have:
Too fast or too slow heart rate
Upper stomach pain
Fever or chills
Flu-like symptoms, such as a runny nose, body aches, and cough
The long-term side effects do not immediately appear after you start taking medicine. They typically develop over several weeks or months.
Abnormally high liver enzymes
People may abuse tizanidine to experience sedation, either for sleep or relaxation. The risk of dependence is high among those who take the drug to relieve sleep problems. Drug abuse can include any of the following deviations from a doctor’s instructions:
Taking more than the recommended doses
Using the drug for longer than recommended duration
Taking medicine more frequently than recommended
Young people are more prone to developing dependence, as they need to take larger doses to feel relaxed. In addition, young people clear the drug from the system four times faster than older people. Users also report mixing the drug with alcohol, other muscle relaxants, and opioids. Using such combinations dramatically increases the odds of overdose.
According to the 2017 Annual Report of National Poison Data System (NPDS), overdose treatment for tizanidine broke down like this:8
4,577 cases that involved tizanidine and other drugs
1,889 cases involving only tizanidine
no deaths associated with tizanidine exposure
An overdose occurs when you take large amounts of a drug within a short period. Tizanidine overdose can be fatal, especially when you take it with alcohol, narcotics, and sleep medications.
Deaths from tizanidine overdose are rare. So far, only a handful of overdose deaths have been reported. An FDA clinical review reported five deaths with doses ranging from 80 mg to 160 mg. Nonetheless, all of them were suicidal overdoses and involved other drugs, such as Ambien, diazepam, and codeine.9
There is no widely accepted toxic dose of the drug. The maximum daily-recommended dose is 36 mg. Anything over 36 mg in 24 hours may be considered toxic. According to a 2004 study, coma may occur with doses ranging from 60 mg to 120 mg.10
Seek emergency medical attention if you think an overdose has occurred. You can also call the Poison Helpline at 1-800-222-1222.
The symptoms of an overdose include:
Low blood pressure
Too slow heart rate
No antidote is currently available, and treatments are supportive. The main goal of treatment is to maintain airway and blood pressure. Intubation (inserting a flexible tube through the mouth into the air passage) may be necessary.
The use of naloxone (Narcan) is controversial and is often ineffective. The following medicines have been used in clinical practice with varying results.
Atropine to increase heart rate
Intravenous fluids and dopamine to increase blood pressure
Never stop using tizanidine on your own. Doing so will make the withdrawal symptoms worse.
Dose tapering helps reduce the odds of severe withdrawal. If you have been taking large doses (20 mg to 36 mg) for two months or longer, your doctor will ask you to reduce the dose gradually (usually 2 mg to 4 mg per day).
Even with proper use, tizanidine causes more severe withdrawal than baclofen and diazepam do. Most withdrawal symptoms occur within the first 12 hours after the last dose. These can include:
Elevated blood pressure
Fast heart rate
Increased muscle tone
Changes in body temperature
Because tizanidine is not considered addictive, there are no specific treatment guidelines. As with other types of addiction, a combination of talk therapy and specific medications is the gold standard of treatment.
Below are some treatment options to consider.
The addiction recovery process starts with detox. Detox is the process of eliminating the drug from the system under medical supervision. It usually lasts a few days. Most people can expect to feel better within 24 hours after starting the detox.
Tizanidine detox helps manage withdrawal symptoms safely. Then, it prepares a person for enrolling in long-term interventions, such as psychotherapy and life skills therapy. Detox at home is not usually recommended, as it may be ineffective or even counterproductive.
CBT is a type of talk therapy (psychotherapy). Many scientific studies show that CBT, alone or combined with medications, is effective in addiction treatment.
CBT helps a person identify problematic thought patterns behind their addictive behaviors. Then, it works to replace those negative thoughts with positive ones. Typically, one CBT session lasts 30 to 60 minutes. Depending on your condition, you may need up to 20 weekly sessions.