How long does it take cyclobenzaprine to work?

In this article:

• How long does cyclobenzaprine take to work?
• What can affect how long it takes cyclobenzaprine to work?
• Dosage
• Who should avoid taking cyclobenzaprine?

In this article

• How long does cyclobenzaprine take to work?
• What can affect how long it takes cyclobenzaprine to work?
• Dosage
• Who should avoid taking cyclobenzaprine?

Cyclobenzaprine is a muscle relaxant sold under the brand names Flexeril and Amrix. A central nervous system (CNS) relaxant, cyclobenzaprine is FDA approved to treat muscle pain and muscle spasms. A doctor may sometimes prescribe cyclobenzaprine off-label to treat fibromyalgia and myofascial pain that occurs as a result of temporomandibular disorders. There is also preliminary evidence that cyclobenzaprine can be helpful in the treatment of post-traumatic stress disorder (PTSD) symptoms.

If you’ve just been prescribed cyclobenzaprine, you might want to know: How long does cyclobenzaprine take to work? Cyclobenzaprine generally provides quick relief, working in about 30 to 60 minutes, depending on the dose and whether you are taking an immediate or extended-release formula of the medication.

How long does cyclobenzaprine take to work? 

So, how fast does cyclobenzaprine work, exactly?

In general, cyclobenzaprine begins to provide relief in 20 to 60 minutes, says Andrew Youssouf, MD, double board-certified in addiction medicine and emergency medicine, and the medical director of Ikon Recovery. “The speed at which it works can depend on the dosage and whether it is immediate-release or extended-release,” he explains.

For immediate-release tablets of cyclobenzaprine, initial effects are often noticed within 30 minutes of taking the medications, and effects tend to peak at about four hours, explains Claudia Cometa, PharmD, pharmacist and founder and CEO at Peace Advocacy Group. Extended-release capsules of cyclobenzaprine—which are less commonly used, according to Dr. Cometa—tend to take a little bit longer to be felt. Extended-release formulations also peak later, with effects reaching maximum effectiveness about seven to eight hours after the dose is taken.

There are two main brands of cyclobenzaprine— Flexeril and Amrix. Dr. Cometa says that there is no discernable difference between the two when it comes to how long they take to work. “There is always the potential for some inter-brand variability, but that would be minimal,” she says. What about taking an increased dose of the drug? “An increased dose would increase the effect, but not necessarily the time to effect,” Dr. Cometa commented.

And how might you know that cyclobenzaprine is beginning to take effect? “You’ll start to notice the medication working when your muscles begin to feel more relaxed,” describes Taher Saifullah, MD, a pain management specialist and founder of Spine & Pain Institute Los Angeles. “For people with tight, knotted muscles or spasms, the relief can feel like a gradual loosening, where it’s easier to move without that gripping pain.”

Additionally, says Dr. Saifullah, many people begin to feel a sense of calm or even mild drowsiness. This is a clear sign that the medication is taking effect. “The intensity of the muscle pain or stiffness usually fades into the background, and some patients describe it like their body has ‘taken a deep breath’ and let go of some of that tension,” Dr. Saifullah shares.

What can affect how long it takes cyclobenzaprine to work?

In general, there are several factors that can affect how long it takes cyclobenzaprine to work. According to Dr. Youssouf, some of these factors include:

• Your metabolism
• Whether you took cyclobenzaprine with food
• The specific form of cyclobenzaprine you are taking (immediate vs. extended-release)
• Other substances and medications you have taking

Your body weight, age, and metabolism all play a role in how long it takes cyclobenzaprine to work, explains Dr. Saifullah. “For example, if you have a slower metabolism or are older, it may take a little longer to feel the effects,” he explains. Additionally, since cyclobenzaprine is processed through the liver, people with liver issues and liver disease might metabolize the medication more slowly, says Dr. Saifullah.

What you put into your body at the time you are taking the medication also has an impact. “Taking the medication with food—especially a heavy or fatty meal—can delay its absorption slightly,” Dr. Saifullah shares. “Certain medications or alcohol can interfere with its effectiveness, particularly sedatives or opioids, which can make you feel excessively drowsy but may not improve muscle relaxation itself.”

What is the standard cyclobenzaprine dosage?

According to DailyMed at the National Institutes of Health, the standard recommended dosage of cyclobenzaprine is 5 mg, taken three times each day. But often, people need to increase the dose to between 7.5 mg or 10 mg, taken three times daily.

Adjustments to the medication are usually made depending on how serious your muscle spasms are, says Dr. Saifullah. “Some patients with more intense conditions might be prescribed an extended-release version, usually 15 mg or 30 mg, which is taken just once a day to cover a full 24-hour period,” he says.

Importantly, cyclobenzaprine should not be taken longer than a few weeks at a time. “Cyclobenzaprine is designed to be a short-term solution, typically for 2 to 3 weeks, because muscle spasms from acute injuries often don’t last much longer than that,” Dr. Saifullah emphasizes.

How many hours does 10 mg of cyclobenzaprine last? 

A 10 mg dose of cyclobenzaprine generally provides relief for about 4 to 6 hours, says Dr. Saifullah. “You’ll likely start feeling the effects wear off after that, but some of the drowsiness or muscle relaxation might linger a bit longer,” he says. “If you’re on the extended-release version, then the medication is designed to last throughout the day, generally up to 24 hours, giving you continuous relief without needing multiple doses.”

Who should avoid taking cyclobenzaprine?

There are certain people who should avoid taking cyclobenzaprine. This includes anyone who is allergic to cyclobenzaprine, or has had an allergic reaction to the added ingredients in any of the formulations.

Additionally, people with certain medical conditions should stay away from cyclobenzaprine, according to Dr. Saifullah. This includes people with a medical history of liver problems or heart problems, especially arrhythmias or recent heart attacks. This is because cyclobenzaprine can put extra strain on the liver or heart.

There are also certain medication interactions to be aware of. “If you’re on antidepressants like SSRIs or MAO inhibitors, you should also be cautious, as cyclobenzaprine can increase the risk of serotonin syndrome, a rare but serious condition where your body has too much serotonin,” says Dr. Saifullah.

Finally, certain populations should steer clear of cyclobenzaprine, Dr. Saifullah warns. This includes pregnant individuals, elderly patients, or anyone with glaucoma or urinary retention. “The side effects in these groups—like dizziness, dry mouth, or trouble urinating—can be more pronounced or problematic,” he describes.

The bottom line

In general, cyclobenzaprine provides quick relief for muscle pain and muscle spasms. It tends to work within 30 to 60 minutes of when you take it. Different formulations, such as extended-release formulations, take a little longer to work but work for a longer period of time. Factors that impact how long it takes cyclobenzaprine to work include your metabolism, what you are eating with the medication, underlying medical conditions you have, and any other medications you are taking along with cyclobenzaprine.

You should always speak to a healthcare professional if you have questions about how long it takes cyclobenzaprine to work, and other questions about safely taking the medication.