1 What is cyclobenzaprine?

Brand: Amrix, Fexmid, Flexeril, FusePaq Tabradol

Generic: Cyclobenzaprine

Cyclobenzaprine is a centrally acting skeletal muscle relaxant which is usually used in patients with acute muscle spasms caused by such conditions as anxiety, inflammation, pain, or trauma.

The skeletal muscle relaxant is a centrally-acting agent; they work by reducing the tone of skeletal muscle. This causes the muscles to relax. There are various classes of drugs that are grouped under "skeletal muscle relaxant". Each of these drugs work differently. Cyclobenzaprine is one such relaxant.

This drug works by blocking the nerve impulses, in other words, the pain sensations, which are sent to the brain. Cyclobenzaprine relieves pain, stiffness, and discomfort caused by any injury or sprain in your muscles.

This medication can also be useful in certain patients with fibrositis or fibromyalgia as well as other medical problems.

When this drug is administered orally, it can take from 30 minutes to 1 hour for effects to be achieved. The duration of action of cyclobenzaprine varies from 12 to 25 hours. This drug is used to treat skeletal muscle conditions, so it should be accompanied by rest and physical therapy.

This drug acts on the central nervous system (CNS). This helps to produce the effects of the muscle relaxant.

Cyclobenzaprine is only available with your doctor's prescription.

This medicine is available in the following dosage forms:

  • Extended release capsule
  • Tablet
  • Suspension

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2 What to know before using

If you are about to start treatment, the risk-benefit ratio of cyclobenzaprine should be considered carefully. This is a decision that your doctor will make with your active participation.

There are some important factors such as

  • Drug interactions
  • Metabolic impairment
  • Hypersensitivity reaction
  • Pregnancy
  • Lactation

These may interact negatively or alter the desired therapeutic effects of such medications.

Animal reproduction studies have failed to show an adverse effect to the fetus while taking cyclobenzaprine, and there are no adequate studies in pregnant as well as lactating women. Therefore, this drug is in pregnancy category B and it can be used in pregnant as well as lactating mothers if clearly needed.

Sometimes the presence of other health disorders affects the beneficial effects of this medicine and even may cause serious toxic effects.

Make sure you tell your doctor if you have any other medical problems, especially:

  • Increased intraocular pressure i.e. glaucoma
  • Urinary tract infections associated with painful micturition and frequent urgency to pass urine
  • Ailments affecting the cardiovascular system
  • Hyperactivity of thyroid gland
  • Hepatic and renal dysfunction

To ensure that cyclobenzaprine is safe for you, do not forget to tell your doctor if you have:

Certain drugs should not be used simultaneously when you are taking such medications.

It is always recommended to speak with your doctor if you need other medications for another health disorder so that you can avoid unwanted serious effects.

Centrally-acting skeletal muscle relaxants (e.g. cyclobenzaprine) interact with other CNS depressants, including

  • Alcohol
  • Aarcotics
  • Barbiturates
  • Anticonvulsants
  • Tricyclic antidepressants
  • Antianxiety drugs

This results in increased sedation, impaired motor function, and respiratory depression.

In addition, some other interactions are reported

  • Cyclobenzaprine interacts with monoamine oxidase inhibitors (MAOIs) and can result in high body temperature, excitation, and seizures.
  • This drug reduces the antihypertensive effects of blood-pressure-lowering drugs guanethidine and clonidine.
  • Sometimes the effects of cholinergic-blocking drugs are enhanced by the use of cyclobenzaprine.

Before starting the course of cyclobenzaprine, the following should be considered:


There are many medicines available in the market which are not studied specifically in the elderly. Therefore, your doctor may not be sure if it works exactly the same as it works on younger people, or there may be some potential side effects on the elderly.

There is no comparison information on the dosage of this drug among various age groups. Older people are more likely to have problem of higher blood pressure, so the cyclobenzaprine extended release capsule is not recommended for them. The kidneys and liver of the elderly also do not work as well as in younger adults. This can cause the drug to process slowly in the body.

Elderly people who are above 65 years of age shouldn’t use the extended release form of this drug. In this case, your doctor may start on a lowered dose or a different schedule.


Mention to your doctor if you ever have any allergic or unusual reaction to certain medicines or this particular drug. Apart from this, also mention any other allergies such as food, animals, preservatives, drugs, etc.


Similar to the geriatric population, there has not been testing done for children. Studies show that testing is only done for adult patients.

Drug interactions

There are times when a warning is issued that two different medicines should not be taken at the same time. In few other cases, different medicines may be used together even if an interaction might occur. Therefore, mention to your doctor if you are simultaneously taking or intend to take other medicines. Drug interaction may change how any medications works, whether it increases any risk of side effects or doesn’t show any potential side effect.

Here are a few medications that should not be taken simultaneously along with cyclobenzaprine:

  • Pimozide
  • Furazolidone
  • Linezolid
  • Selegiline
  • Terfenadine
  • Ziprasidone
  • Thioridazine
  • Sparfloxacin
  • Mesoridazine
  • Cisapride
  • Methylene Blue
  • Dronedarone
  • Moclobemide
  • Safinamide
  • Pargyline

Let your doctor know if you are taking other medications that can also cause symptoms such as drowsiness, antihistamines, are taking drugs for sleep or anxiety (such as zolpidem, diazepam, alprazolam) or other muscle relaxant drugs and pain relievers.


Studies have revealed that no harm has been done on the fetus by intake of this medicine. However, proper consultation is a must.


Weigh the potential benefits and risk before taking this medicine during the breastfeeding period. Consultation with your doctor is necessary. Cyclobenzaprine may pass into breast milk which can cause side effects in a child who is feeding.

3 Proper usage

All medications should be used following the directions given by your doctor. The frequency of your daily drug administration and the duration of drug therapy depend on the particular medical problem for which you are taking the medicine.

That’s why the therapeutic dose may vary with the patient’s condition or requirement. In order to treat acute and painful musculoskeletal conditions, patients are usually prescribed to receive cyclobenzaprine or other centrally-acting skeletal muscle relaxants along with adequate bed rest and physical therapy.

Cyclobenzaprine is usually taken once daily for two to three weeks. It is a must to follow all the directions prescribed on the medicine label or by your doctor. Take the medicine daily at the same time. Swallow it as a whole. Do not chew, break, or open an extended release capsule.

Once you stop taking this medicine after taking it for a long time, you may experience withdrawal symptoms.

For relaxation of stiff muscles:

When tablets are prescribed:

  • Adults and teenagers 15 years of age and older are usually treated with a 10 mg tablet which should be taken three times in a day. The usual dose may be increased if necessary but not exceeding 60 mg in 24 hours.
  • Children and teenagers up to 15 years of age should follow instructions given by the doctor.

When extended-release capsules are prescribed:

  • In case of adults, the usual dose is 15 mg once daily. Some patients may need up to 30 mg (one 30 mg capsule or two 15 mg capsules) per day.
  • The therapeutic dosage schedule for children must be determined by a pediatrician.

You should not stop this medicine until the prescribed course is finished, even if you begin to feel much better.

If you miss any dose of this medicine, you should take it as soon as possible. If it is time for your next dose, then you should skip the missed dose and go back to your regular treatment schedule.

You should store the medicine in a closed container at room temperature away from heat, moisture, and direct light. All kinds of medicines should be kept out of the reach of children. Check with your doctor about how you should dispose of the medicine if not being used.

Outdated medicines should be disposed of appropriately.

If you suspect you or a loved one have overdosed, seek emergency help, since an overdose of cyclobenzaprine can prove fatal.

Symptoms of overdose include:

  • Severe restlessness
  • Flushed skin
  • Hallucinations
  • Muscle stiffness which cannot be explained
  • Severe drowsiness
  • Having troubles while breathing
  • Irregular heartbeat
  • Sudden rise and fall in body temperature
  • Vomiting
  • Convulsions

4 Precautions to take

This medicine is responsible for the additive effects of alcohol and other CNS depressants (medicines possibly causing drowsiness).

You should avoid using certain CNS depressants including antihistamines or medicine for

  • Hay fever
  • Sedatives, tranquilizers, or narcotics
  • Barbiturates
  • Medicine for seizures
  • Other muscle relaxants
  • Anesthetics

Additionally, this drug may cause

  • Blurred vision
  • Drowsiness
  • Dizziness
  • Dryness of the mouth

Therefore, make sure you know how you react to this medicine before you drive or do anything else (e.g. operating heavy machinery) that could be dangerous if you are dizzy or are not alert and able to see well.

Sugarless candy or gum, or a saliva substitute can help patients to get rid of dry mouth.

You should not use the extended release capsule if you have used an MAO inhibitor within the past 14 days. MAOI include ELdepryl, Parnate, Nardil, Marplan.

However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist immediately.

Continuing dryness of the mouth may enhance the risk of dental diseases, including:

  • Tooth decay
  • Gum disease
  • Fungal infections

If your condition does not show any signs of improvement within the span of two to three weeks or if the condition turns severe, then its recommended to reach out to your doctor as soon as possible.

However, regular visits are always recommended while you are using this drug. It will help your doctor to assess your progress and to make sure that this drug is working properly.

5 Potential side effects

There are some unwanted side effects associated with each drug that usually do not need medical attention. These side effects usually go away during the treatment episode as your body adjusts to the medicine.

Your healthcare professional may advise you about the ways how to prevent or reduce those unwanted adverse effects. Physical and psychological dependence may develop after long-term use of such medications.

Sudden stopping of this drug therapy can cause severe withdrawal symptoms. Some side effects are detailed below.




If you come across any of the below symptoms due to this medicine, stop taking the medication and call your doctor immediately:

  • Fast heart rate
  • Fluttering in your chest or pounding heartbeats
  • Hallucinations
  • Fever
  • Loss of coordination
  • Agitation
  • Fainting and hallucinations
  • Nausea
  • Vomiting
  • Clumsiness
  • Buzzing sound in the ears
  • Problems while urinating
  • Eyes or skin turning yellow, changes in the skin color
  • Large swellings on the face, eyelids, tongue, lips or mouth. These swellings look like hives.

Monitoring post-medication

The response to the therapy is measured by relief of the muscle spasms and the associated symptoms such as tenderness in the affected area, pain and limitation in motion. Monitoring the patient for anticholinergic toxicity is necessary. Monitoring any development of serotonin syndrome is also necessary, as this can be dangerous.