Tizanidine (Zanaflex) is a muscle relaxer used to treat stiff, rigid muscles. It's taken by mouth, typically 3 times a day. Tizanidine (Zanaflex) isn't a controlled substance, so it isn't known to cause an addiction. But it does have several risks and warnings for side effects such as low blood pressure, dry mouth, and sleepiness. Tizanidine (Zanaflex) comes as both brand and generic name tablets and capsules.
Tizanidine (Zanaflex) is a type of muscle relaxer called an alpha-2 adrenergic receptor agonist. It works by slowing down nerves in your spinal column that control muscle tone. When those nerves slow down, your muscles relax.
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Contact your healthcare provider immediately if you experience any of the following.
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
Chest pain or discomfort
fever or chills
nausea or vomiting
nervousness
pain or burning while urinating
unusual tiredness
Less common
Blurred vision
flu-like symptoms
irregular heartbeat
itching skin
right upper stomach tenderness
seeing things that are not there
shortness of breath
Incidence not known
Continuing vomiting
general feeling of tiredness or weakness
headache
light-colored stools
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
Blurred vision
change in consciousness
chest pain or discomfort
confusion
decreased awareness or responsiveness
difficult or troubled breathing
dizziness, faintness or lightheadedness when getting up from a lying position
irregular, fast or slow, or shallow breathing
lightheadedness, dizziness, or fainting
loss of consciousness
pale or blue lips, fingernails, or skin
severe sleepiness
sleepiness or unusual drowsiness
slow or irregular heartbeat
sweating
unusual tiredness or weakness
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Dizziness or lightheadedness, especially when getting up from a lying or sitting position
drowsiness
sleepiness
weakness
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Take tizanidine (Zanaflex) as instructed by your provider. Tizanidine (Zanaflex) tablets come in a few different strengths. How many tablets you can take per dose depend on the total milligrams you've been prescribed and what strength of tizanidine (Zanaflex) tablets you've been dispensed. If you're starting tizanidine (Zanaflex) for the first time, your provider will typically prescribe tizanidine (Zanaflex) 2 mg every 6 to 8 hours as needed, for a maximum of 3 doses per day. Never take more tizanidine (Zanaflex) than what's been prescribed without being told to do so by your provider. Doing so can lead to serious side effects, such as dangerously low blood pressure and extreme sleepiness.
No, tizanidine (Zanaflex) isn't a narcotic. A narcotic is an opioid pain reliever. Tizanidine (Zanaflex) is a muscle relaxer and doesn't treat pain the same way a narcotic medication does.
In general, you'll start to feel the effects of tizanidine (Zanaflex) about 1 to 2 hours after you take your dose. But this can differ depending on whether you're taking tizanidine (Zanaflex) capsules or tablets, and whether you have food in your stomach. If you take tizanidine (Zanaflex) tablets with food, you might feel their effects more quickly. But if you take tizanidine (Zanaflex) capsules, it can take longer before you experience their effects.
After the effect of tizanidine (Zanaflex) kicks in (which might take 1 to 2 hours), you can expect it to last up to 6 hours after that. Because of this, your provider will probably prescribe one dose of tizanidine (Zanaflex) every 6 to 8 hours.
Tizanidine (Zanaflex) isn't FDA-approved to help with sleep. But some researchers have studied how tizanidine (Zanaflex) might help certain people with muscle stiffness and rigidity fall asleep and stay asleep. Because tizanidine (Zanaflex) can cause extreme sleepiness as a side effect, some providers might consider this medication for people with insomnia that's caused by muscle spasticity problems. If you have questions about tizanidine (Zanaflex) and sleep, talk with your provider.
Tizanidine (Zanaflex) doesn't cause physical and mental dependence like controlled substances do. But it can cause withdrawal symptoms (e.g., high blood pressure, tremors, muscle rigidity, anxiety) if you stop taking it all of a sudden. These symptoms are more likely to happen if you've been taking higher doses of tizanidine (Zanaflex) for a long period of time. If you want to stop taking tizanidine (Zanaflex), talk with your provider so they can help you lower your dose slowly and avoid withdrawal symptoms.
People who took tizanidine (Zanaflex) in clinical trials didn't report weight gain as a side effect. If you find yourself gaining weight, speak with your provider because it could be caused by something else.
More research is needed to understand if tizanidine (Zanaflex) is safe to take during pregnancy. Animal studies suggest that birth defects aren't likely, but still possible. Talk with your provider if you're pregnant or thinking of becoming pregnant. They can recommend a muscle relaxant that's safer to take during pregnancy.
While both tizanidine (Zanaflex) and cyclobenzaprine (Flexeril) are muscle relaxers, they're not the same medication. Tizanidine (Zanaflex) is used for muscle spasticity, which can be thought of as stiff or rigid muscles that won't relax. It's helpful for certain conditions, like multiple sclerosis (MS). On the other hand, cyclobenzaprine (Flexeril) is typically only taken for a short period of time to treat muscle spasms that result from an injury, such as through sports or a car accident.
Tizanidine (Zanaflex) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Tizanidine (Zanaflex) can cause low blood pressure and dizziness, especially when you first start the medication and any time your provider raises your dose. Your provider will try to minimize these side effects by raising your dose slowly over time. To lower your risk of falls, make sure you stand up slowly from a lying position and use a sturdy object to help yourself up. If you continue to feel dizzy or unsteady, or if your blood pressure is too low, talk to your provider.
Taking tizanidine (Zanaflex) can make you feel sleepy and affect your concentration and focus. This is more likely to happen if you're over 65 or take other medications that cause drowsiness. Don't drink alcohol while taking this medication. Avoid activities that require you to be alert, like driving or operating machinery, until you know how the medication affects you.
There are certain medications that can interact with tizanidine (Zanaflex) and worsen low blood pressure and dizziness. For example, you're not recommended to take tizanidine (Zanaflex) along with clonidine (Catapress) or guanfacine. And you need to avoid taking tizanidine (Zanaflex) if you take either fluvoxamine (Luvox) or ciprofloxacin (Cipro).
Make sure to tell both your healthcare provider and your pharmacist about all medications and over-the-counter products you are taking before you start tizanidine (Zanaflex), even if you only take them once in a while or as needed.
People who have kidney problems should be careful using tizanidine (Zanaflex). Tizanidine (Zanaflex) is processed by the kidneys, and if the kidneys aren't working properly, you could have a buildup of tizanidine (Zanaflex) in your body. This buildup can raise your risk of side effects like drowsiness and dizziness or make them more intense. If you have kidney problems, you will most likely be given lower doses of tizanidine (Zanaflex) to prevent these issues.
Tizanidine (Zanaflex) can cause liver injury. If you have liver problems, you might not be able to take this medication. Or, your provider might ask you to get blood tests done regularly to check your liver health.
A very small number of people have experienced hallucinations after starting tizanidine (Zanaflex). For most people, the hallucinations went away once they stopped taking the medication. Talk to your healthcare provider if this happens to you. There might be alternative muscle relaxers that are better options for you.
If you stop taking tizanidine (Zanaflex) suddenly, you might experience withdrawal symptoms, including high blood pressure, a fast heartbeat, and muscle stiffness. This is more common if you've been taking a total of 20 mg to 36 mg per day for more than 9 weeks and then suddenly stop. It's also more likely to happen if you are taking both tizanidine (Zanaflex) and certain pain medications, such as oxycodone or morphine. Talk to your healthcare provider if you would like to stop taking tizanidine (Zanaflex). They can help you lower your dose safely.
Severe allergic reactions to tizanidine (Zanaflex) are possible, including life-threatening problems like anaphylaxis (closing of the throat). Call 911 if this happens. If you notice hives, a rash, swelling of the lips or tongue, or difficulty breathing after using tizanidine (Zanaflex), call your healthcare provider right away.
Your dose might be different if you have liver or kidney problems.
GoodRx has partnered with to provide reviews on the different aspects of Tizanidine (Zanaflex).
Learn more about the effectiveness of Tizanidine (Zanaflex) based on real life experiences.
Based on 174 people taking this medication
2.7
3.0
1.9
1.5
4.5
2.5
Severity of side effects
Based on 763 people taking this medication
0%
50%
100%
Sleepiness
10%
Drowsiness
10%
Dry mouth
7%
Excessive daytime sleepiness (somnolence)
4%
Fatigue
4%
Reasons people stopped taking Tizanidine (Zanaflex)
Based on 551 people who have taken this medication
Did not seem to work
32%
Side effects too severe
20%
Doctor's advice
19%
Other
18%
Course of treatment ended
5%
Personal research
4%
Expense
4%
Change in health plan coverage
2%
How long people take Tizanidine (Zanaflex)
Based on 2067 people who have taken this medication
0%
50%
100%
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Tizanidine (Zanaflex) will not be safe for you to take.