What is the difference between Baclofen and Cyclobenzaprine for Muscle Spasms ?

Many people experience muscle cramps (spasms) every now and then. Muscle spasms typically occur when we overuse or injure our muscles. While these cramps can be painful, they usually last for only a few seconds or minutes.

But for some people, muscle spasms are frequent and intensely painful. The spasms can also last for long periods of time. When a spasm hits, severe symptoms can negatively impact your quality of life.

Fortunately, medications are available that can help relieve your symptoms. Two common muscle relaxer medications are baclofen and cyclobenzaprine (Flexeril). They’re routinely filled at pharmacies across the country with a similar treatment goal in mind, but they’re given for different reasons.

Here, we’ll compare baclofen and cyclobenzaprine — what they are, how effective they are, and what side effects to expect.

What is baclofen?

Baclofen is a prescription medication that’s usually taken by mouth. It can also be given as a spinal injection (Gablofen).

Baclofen is considered to be an antispastic muscle relaxant or a spasmolytic, which is used to treat muscle spasms due to brain injury or nerve damage.

What is baclofen approved to treat?

Antispastic muscle relaxants — like baclofen — are used for muscle spasticity conditions. For these conditions, people have unusually tight, stiff, and rigid muscles that repeatedly spasm because of brain injury or nerve damage.

In fact, the FDA approved baclofen to treat muscle spasticity symptoms caused by spinal injuries or spine-related medical conditions. The FDA also approved baclofen to relieve similar symptoms in people with multiple sclerosis (MS), a type of autoimmune disorder.

How does baclofen work for muscle spasms?

Baclofen is thought to work by affecting the spinal nerves. It lessens the number and severity of muscle spasms. It also relieves pain, loosens rigid muscles, and helps with muscle movement.

What is cyclobenzaprine?

Like baclofen, cyclobenzaprine is a prescription medication that’s taken by mouth. But unlike baclofen, cyclobenzaprine is an antispasmodic muscle relaxant. This means it’s used to treat muscle spasms due to muscle and bone problems.

What is cyclobenzaprine approved to treat?

Cyclobenzaprine is routinely used to treat muscle spasms caused by musculoskeletal conditions. These are muscle spasms related to problems from the muscles and bones — not the brain or spine.

These types of muscle spasms can also be painful. But the pain is usually acute (short-term), not chronic. So, the FDA only approved cyclobenzaprine use for 2 to 3 weeks at a time to relieve painful muscle spasms from these musculoskeletal conditions. Cyclobenzaprine should also be used in combination with rest and physical therapy when possible.

How does cyclobenzaprine work for muscle spasms?

Cyclobenzaprine is thought to relax muscles by mainly working in the brain. To a lesser extent, it also exerts its effects on the spine. It doesn’t work by affecting muscles directly.

How are baclofen and cyclobenzaprine dosed and given?

The following table contains information on how baclofen and cyclobenzaprine oral tablets are dosed and given.

Baclofen Cyclobenzaprine
Tablet strengths 5 mg
10 mg
20 mg
5 mg
7.5 mg
10 mg
Typical starting dose 5 mg by mouth 3 times daily 5 mg by mouth 3 times daily
Usual maximum daily dose 20 mg by mouth 4 times daily 10 mg by mouth 3 times daily
Duration of Use 1-2 months, or until you and your healthcare provider decide to slowly stop the medication 2-3 weeks
Kidney or liver function affects dosing Yes, kidney Yes, liver

As a reminder, baclofen is also given as an injection into the back. It’s also available as an oral (by mouth) liquid. Cyclobenzaprine is also available as an oral capsule. If you have any questions about how these other dosage forms are used, talk with your pharmacist or healthcare provider.

How effective are baclofen and cyclobenzaprine for treating muscle spasms?

For muscle spasticity conditions — especially spinal injuries — experts consider baclofen as a possible first-choice option. Clinical trials showed that baclofen improved muscle tone in up to 72% of study participants.

For muscle spasms caused by muscle and bone issues, cyclobenzaprine is considered moderately effective. Studies have suggested that people taking cyclobenzaprine are 5 times more likely than placebo (a pill with no medication in it) to experience improvement in pain-related muscle symptoms.

What are the known side effects of baclofen and cyclobenzaprine?

Like all medications, both baclofen and cyclobenzaprine have a number of side effects. Some are common to both medications, and some are more unique to just one. Side effects can also vary by dose and dosage form (pill, injection, etc).

The following are some common side effects for common doses of baclofen and cyclobenzaprine:

Side effect Baclofen Cyclobenzaprine
Drowsiness 10-63% 29%
Dry mouth Rare 21%
Dizziness 5-15% 1-3%
Weakness 5-15% Less than 1%
Headache 4-8% 5%

What are the serious side effects of baclofen?

A number of rare but serious side effects are also possible. If you experience serious side effects with baclofen, such as the ones below, get medical help right away.

Sudden discontinuation (withdrawal) symptoms

Abruptly stopping baclofen can cause severe withdrawal symptoms, which can include seizures, unusual behavior, and more.

If you would like to stop using baclofen, talk with your healthcare provider first. They can help you slowly stop the medication to prevent withdrawal side effects.

Withdrawal symptoms in newborn babies

If you’re taking baclofen throughout your pregnancy, your healthcare provider may want to slowly stop this medication before your delivery date to limit withdrawal side effects in your baby. This is because within hours to days after delivery, newborn babies can experience withdrawal symptoms, such as rigid muscles, tremors, and seizures.


In people with epilepsy, baclofen can raise the odds of having seizures. Your healthcare provider may want to closely monitor your brain waves over time to keep your seizure risk in check.

What are the serious side effects of cyclobenzaprine?

For cyclobenzaprine, seek immediate medical attention if you have symptoms like serotonin syndrome, heart-related side effects, or other similar symptoms.

Serotonin syndrome

Serotonin syndrome is a rare but potentially life-threatening condition. Symptoms of serotonin syndrome may include confusion, sweating, seizures, and tremors. Risk of serotonin syndrome is higher when you take cyclobenzaprine with other medications that raise serotonin levels. Serotonin is a naturally-occurring chemical in the body.

Heart-related side effects

Cyclobenzaprine might raise your risk for heart-related side effects, including a fast heartbeat and abnormal heart rhythm.

What interactions do baclofen and cyclobenzaprine have?

In general, don’t take baclofen or cyclobenzaprine with alcohol, opioid medications, or benzodiazepines. These can worsen side effects of your medication, like drowsiness or sleepiness.

You should also avoid taking cyclobenzaprine within 14 days of taking a monoamine oxidase inhibitor (MAOI). Combining cyclobenzaprine and MAOIs drastically raises your risk of serotonin syndrome. Examples of MAOIs include linezolid (Zyvox) and selegiline (Emsam).

Additionally, when taking cyclobenzaprine, use caution with tramadol (Ultram). Combining these two medications can worsen your seizure risk.

This is not a complete list of drug interactions for baclofen and cyclobenzaprine. For more detailed information about medication interactions for each muscle relaxant, talk with your pharmacist or healthcare provider.

6 Baclofen Interactions You Should Watch Out for

Like most medications, baclofen has drug interactions to be aware of. Interactions can occur with other medications and substances that have similar effects on the body. This includes sleepiness, dizziness, and weakness. In rare instances, this can lead to severe side effects like difficulty breathing.

Below we’ll discuss a few medications and substances that can interact with baclofen. But this isn’t a complete list. Talk to your healthcare provider and pharmacist before starting baclofen. Provide them with an updated list of all your medications. They can help you check for possible baclofen interactions.

1. Alcohol

Muscle relaxers, like baclofen, may interact with alcohol. Drinking alcohol while taking baclofen can cause weakness, dizziness, and confusion.

Baclofen and alcohol impact the central nervous system (CNS). The CNS consists of your brain and spinal cord. Medications and substances that lower the activity of the CNS can cause symptoms:

  • Lowered concentration
  • Confusion
  • Headache
  • Dizziness
  • Slowed speech
  • Problems with coordination
  • Worsening memory
  • Lower blood pressure
  • Slowed breathing

When alcohol and baclofen are combined, these side effects are more likely. If you drink alcohol, talk with your healthcare provider before starting baclofen. They can provide guidance on how much alcohol, if any, is safe to drink with your medication.

2. Opioids

Opioids are a class of medications that are usually used to treat moderate to severe pain. Examples of opioids include oxycodone (Oxycontin, Roxicodone), morphine (MS Contin, Kadian), and tramadol (Ultram).

Individually, opioids and baclofen can both cause your brain to slow down. In 2016, the FDA warned about the risk of combining opioids with other medications that affect the brain. This includes baclofen. They warned that a combination of these medications can cause serious side effects. Slowed and ineffective breathing is possible, and can lead to death in severe cases.

If you take opioids, it’s a good idea to have Narcan (naloxone) on hand at all times. This is especially important if you’re taking opioids with a medication that amplifies opioid effects. You can get Narcan without a prescription at your local pharmacy in every state. And in some states, you can get Narcan for free.

Before starting baclofen, make sure to tell your healthcare provider if you’re taking opioids. They may recommend you slowly lower your opioid dose if baclofen is needed. Or they may recommend another medication besides baclofen. It’s important to note that the prescribing information for intrathecal baclofen has a specific warning about epidural morphine. Epidural morphine is administered into the spine. Combining these two products can cause difficulty breathing and low blood pressure.

3. Benzodiazepines

Benzodiazepines (BZDs) are a group of medications that treat many health conditions, including anxiety, panic disorder, and more. A few examples of medications in this class include alprazolam (Xanax), clonazepam (Klonopin), and lorazepam (Ativan).

Like opioids, BZDs can slow down your brain, and cause similar side effects as those caused by baclofen. This can lead to more serious symptoms such as slow and shallow breathing, and even death.

If you take BZDs, talk with your healthcare provider before starting baclofen. They may recommend stopping your BZD or adjusting the dose. Or they may recommend avoiding baclofen. But, don’t make any changes to your medications without talking to your healthcare provider. Stopping medications like BZDs abruptly can be dangerous.

4. Sleep medications

Sleep medications — like zolpidem (Ambien) and doxylamine (Unisom Sleep Tabs) — can cause excessive sleepiness when taken with baclofen. Medications that aren’t approved for sleep (but cause sleepiness as a side effect) can also interact with baclofen. This includes trazodone, diphenhydramine (Benadryl), and gabapentin (Neurontin).

Excessive sleepiness can lead to trouble with coordination. It can also impact your ability to complete daily tasks. If you take sleep medication, let your healthcare provider know before starting baclofen. They may recommend you avoid one of these medications entirely.

If you need baclofen and a sleep medication, avoid activities that require you to be alert until you know how the combination affects you. That includes driving and operating heavy machinery.

5. Barbiturates

Barbiturates are a group of medications that treat seizures and sleep problems. Examples include phenobarbital and pentobarbital. Pentobarbital is only used in hospitals because it’s given through a vein.

Barbiturates slow down brain activity and can cause drowsiness on their own (which is what they’re often used for). When combined with baclofen, the risk for severe drowsiness is higher.

If you need a barbiturate, your healthcare provider may recommend stopping baclofen slowly. Or, they may ask you to monitor closely for side effects. These include extreme sleepiness, confusion, or trouble breathing.

6. Other muscle relaxers

There are multiple other muscle relaxers available besides Baclofen. Examples include methocarbamol, cyclobenzaprine (Fexmid, Amrix), and tizanidine (Zanaflex). While these medications don’t all necessarily work just like baclofen, they have a similar effect of muscle relaxation. They can also cause dizziness and drowsiness. When combined with baclofen, these effects can be amplified.

In general, it’s best to avoid taking multiple muscle relaxers at once. If you’re taking baclofen and not feeling relief, talk to your healthcare provider. They may recommend an alternative option.