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- Take the Pain Quiz
- Joint-Friendly Exercises to Reduce RA Pain Slideshow
- Does Flexeril (cyclobenzaprine) cause side effects?
- What are the important side effects of Flexeril (cyclobenzaprine)?
- Flexeril (cyclobenzaprine) side effects list for healthcare professionals
- Does Flexeril (cyclobenzaprine) cause addiction or withdrawal symptoms?
- What drugs interact with Flexeril (cyclobenzaprine)?
Does Flexeril (cyclobenzaprine) cause side effects?
Flexeril (cyclobenzaprine) is a muscle relaxant used with rest and physical therapy for short-term relief of muscle spasms associated with acute painful muscle and skeletal conditions. It is only for short-term use, up to two or three weeks.
Flexeril is used to relieve muscle spasm when the spasm is due to local problems, that is, in the muscle itself and not in the nerves controlling the muscles. Flexeril has no effect on muscle function. Flexeril seems to accomplish its beneficial effect through a complex mechanism within the nervous system, probably in the brainstem.
Common side effects of Flexeril include
Serious side effects of Flexeril include
- Flexeril should not be taken with or within two weeks of any monoamine oxidase inhibitors (MAOs) for example, isocarboxazid, phenelzine, tranylcypromine, and procarbazine.
- High fever, convulsions, and even death can occur when these drugs are used together.
- Flexeril interacts with other medications and drugs that slow the brain's processes, such as alcohol, barbiturates, benzodiazepines, and narcotics.
There are no adequate studies of Flexeril in pregnant women. Studies in animals suggest no important effects on the fetus. Flexeril therefore can be used in pregnancy if the physician feels it is necessary.
It is unknown if Flexeril is secreted in breast milk. Since it is related to tricyclic antidepressants, some of which are excreted in breast milk, caution is advised in using Flexeril in women who are breastfeeding.
What are the important side effects of Flexeril (cyclobenzaprine)?
The most common side effects of cyclobenzaprine include:
Other reported side effects include:
- Blurred vision,
- Unpleasant taste
- Acid reflux
- Abdominal pain or discomfort
Possible serious side effects include:
Abrupt cessation after prolonged therapy may cause withdrawal symptoms such as headaches, nausea, and weakness.
Flexeril (cyclobenzaprine) side effects list for healthcare professionals
Incidence of most common adverse reactions in the 2 double-blind‡, placebo-controlled 5 mg studies (incidence of > 3% on Flexeril 5 mg):
|Flexeril 5 mg
|Flexeril 10 mg
Adverse reactions which were reported in 1% to 3% of the patients were:
- abdominal pain,
- acid regurgitation,
- mental acuity decreased,
- upper respiratory infection, and
The following list of adverse reactions is based on the experience in 473 patients treated with Flexeril 10 mg in additional controlled clinical studies, 7607 patients in the post-marketing surveillance program, and reports received since the drug was marketed. The overall incidence of adverse reactions among patients in the surveillance program was less than the incidence in the controlled clinical studies.
The adverse reactions reported most frequently with Flexeril were
- dry mouth and
The incidence of these common adverse reactions was lower in the surveillance program than in the controlled clinical studies:
‡ Note: Flexeril 10 mg data are from one clinical trial. Flexeril 5 mg and placebo data are from two studies.
|Clinical Studies With Flexeril 10 mg||Surveillance Program With Flexeril 10 mg|
Among the less frequent adverse reactions, there was no appreciable difference in incidence in controlled clinical studies or in the surveillance program. Adverse reactions which were reported in 1% to 3% of the patients were:
- unpleasant taste,
- blurred vision,
- nervousness, and
The following adverse reactions have been reported in post-marketing experience or with an incidence of less than 1% of patients in clinical trials with the 10 mg tablet:
- Body as a Whole: Syncope; malaise.
- Cardiovascular: Tachycardia; arrhythmia; vasodilatation; palpitation; hypotension.
- Digestive: Vomiting; anorexia; diarrhea; gastrointestinal pain; gastritis; thirst; flatulence; edema of the tongue; abnormal liver function and rare reports of hepatitis, jaundice and cholestasis.
- Hypersensitivity: Anaphylaxis; angioedema; pruritus; facial edema; urticaria; rash.
- Musculoskeletal: Local weakness.
- Nervous System and Psychiatric: Seizures, ataxia; vertigo; dysarthria; tremors; hypertonia; convulsions; muscle twitching; disorientation; insomnia; depressed mood; abnormal sensations; anxiety; agitation; psychosis, abnormal thinking and dreaming; hallucinations; excitement; paresthesia; diplopia.
- Skin: Sweating.
- Special Senses: Ageusia; tinnitus.
- Urogenital: Urinary frequency and/or retention.
Causal Relationship Unknown
Other reactions, reported rarely for Flexeril under circumstances where a causal relationship could not be established or reported for other tricyclic drugs, are listed to serve as alerting information to physicians:
- Body as a whole: Chest pain; edema.
- Cardiovascular: Hypertension; myocardial infarction; heart block; stroke.
- Digestive: Paralytic ileus, tongue discoloration; stomatitis; parotid swelling.
- Endocrine: Inappropriate ADH syndrome.
- Hematic and Lymphatic: Purpura; bone marrow depression; leukopenia; eosinophilia; thrombocytopenia.
- Metabolic, Nutritional and Immune: Elevation and lowering of blood sugar levels; weight gain or loss.
- Musculoskeletal: Myalgia.
- Nervous System and Psychiatric: Decreased or increased libido; abnormal gait; delusions; aggressive behavior; paranoia; peripheral neuropathy; Bell's palsy; alteration in EEG patterns; extrapyramidal symptoms.
- Respiratory: Dyspnea.
- Skin: Photosensitization; alopecia.
- Urogenital: Impaired urination; dilatation of urinary tract; impotence; testicular swelling; gynecomastia; breast enlargement; galactorrhea.
Does Flexeril (cyclobenzaprine) cause addiction or withdrawal symptoms?
Drug Abuse And Dependence
- Pharmacologic similarities among the tricyclic drugs require that certain withdrawal symptoms be considered when Flexeril is administered, even though they have not been reported to occur with this drug.
- Abrupt cessation of treatment after prolonged administration rarely may produce nausea, headache, and malaise. These are not indicative of addiction.
What drugs interact with Flexeril (cyclobenzaprine)?
- Flexeril may have life-threatening interactions with MAO inhibitors.
- Flexeril may enhance the effects of alcohol, barbiturates, and other CNS depressants.
- Tricyclic antidepressants may block the antihypertensive action of guanethidine and similarly acting compounds.
- Tricyclic antidepressants may enhance the seizure risk in patients taking tramadol.†
Flexeril (cyclobenzaprine) is a muscle relaxant used with rest and physical therapy for short-term relief of muscle spasms associated with acute painful muscle and skeletal conditions. Common side effects of Flexeril include drowsiness, dry mouth, fatigue, headaches, and dizziness. Other reported side effects of Flexeril include nausea, constipation, blurred vision, unpleasant taste, nervousness, confusion, acid reflux, and abdominal pain or discomfort. There are no adequate studies of Flexeril in pregnant women. It is unknown if Flexeril is secreted in breast milk. Since it is related to tricyclic antidepressants, some of which are excreted in breast milk, caution is advised in using Flexeril in women who are breastfeeding.
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Second Source article from WebMD
Muscle cramps are involuntarily and forcibly contracted muscles that do not relax. Extremely common, any muscles that have voluntary control, including some organs, are subject to cramp. Since there is such variety in the types of muscle cramps that can occur, many causes and preventative medications are known. Stretching is the most common way to stop or prevent most muscle cramps.
Pain Management: Musculoskeletal Pain
Natural menopause is the permanent ending of menstruation that is not brought on by any type of medical treatment. For women undergoing natural menopause, the process is described in three stages: perimenopause, menopause, and postmenopause. However, not all women undergo natural menopause. Some women experience induced menopause as a result of surgery or medical treatments, such as chemotherapy and pelvic radiation therapy.
Muscle Pain (Myofascial Pain Syndrome)
Muscle pain (myofascial pain syndrome) is muscle pain in the body's soft tissues due to injury or strain. Symptoms include muscle pain with tender points and fatigue. Treatment usually involves physical therapy, massage therapy, or trigger point injection.
Pain Relief Options for Childbirth
Women experience and tolerate pain differently. For some pregnant women, focused breathing is all they need to get through labor and childbirth; but for others, numbing of the pain is desired. There are a number of different medications a woman can take during labor and childbirth. It is important for you to learn what pain relief options are available. Please discuss the options with your health care provider well before your "birth day" so that when you are in labor you understand the choices.
Pain management and treatment can be simple or complex, according to its cause. There are two basic types of pain, nociceptive pain and neuropathic pain. Some causes of neuropathic pain include: complex regional pain syndrome, interstitial cystitis, and irritable bowel syndrome. There are a variety of methods to treat chronic pain, which are dependant on the type of pain experienced.
Muscle spasms are involuntary muscle contractions that come on suddenly and are usually quite painful. Dehydration, doing strenuous exercise in a hot environment, prolonged muscle use, and certain diseases of the nervous system may cause muscle spasms. Symptoms and signs of a muscle spasm include an acute onset of pain and a possible bulge seen or felt beneath the skin where the muscle is located. Gently stretching the muscle usually resolves a muscle spasm.
Pain Management: Neuropathic Pain
Neuropathic pain is chronic pain resulting from injury to the nervous system. The injury can be to the central nervous system (brain and spinal cord) or the peripheral nervous system (nerves outside the brain and spinal cord).
Muscle Cramps: Treatment
Muscle cramps cannot be stopped instantly with injections or pills, but some methods can be useful to relieve them which include stretching, massage, application of heat and cold, walking and taking B vitamins.
What Causes Pain in the Trapezius Muscle?
Trapezius or ‘trap’ muscle pain is often known as acute or severe pain that affects a number of small muscles in the upper back and neck.
What Does the Trapezius Muscle Do?
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How Long Does It Take for a Muscle Strain to Heal?
A muscle strain occurs when muscle fibers are overstretched and tear. Learn more about muscle strains, how muscle strains happen, muscle strain symptoms, muscle strain diagnosis, and muscle strain treatment options.
Why Does My Deltoid Muscle Hurt?
Shoulder pain is a common problem that may be caused by an injured deltoid muscle. Learn the signs and causes of a deltoid injury, how to treat it, and when you should see a doctor.
What Is the Best Thing for Sore Muscles?
Exercise may be vital for overall health and longevity, but it comes with pains and sprains. After a robust exercise session, your muscles may get sore or stiff. Slight soreness is a normal response to exercise, but there are good and bad soreness. Soreness should last for a day or two; if it lasts for more than 2 days along with signs of persistent pain, black-and-blue hued bruising, and numbness, then immediately consult a physician.
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Treatment & Diagnosis
- Muscle Cramps
- Pain Management: Dealing with Back Pain
- Pain Management
- Pain Management: Painkiller Addiction
- Chronic Pain Treatments for Mind and Body
- Chronic Pain: Implantable Pain Control Devices
- Pain Awareness and Management
- Mind-Body-Pain Connection: How Does It Work?
- Chronic Pain and Fatigue - What You Can Do
- Pain Management: Routes to Relief
- Muscle Pain (Myalgia)
- Neuropathic Pain
- Pain FAQs
- Pain and Stress: Endorphins: Natural Pain and Stress Fighters
- Macrophagic Myofasciitis
- Pain Management: OTC NSAIDs - Doctors Dialogue
- Pain Management Over-The-Counter
- Myositis Muscle (Pain and Inflammation) Serious Drug Interactions
- Pain (Acute and Chronic)
- Progressive Muscle Relaxation
- Doctors Answer Pain Questions
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- What Causes Rectal Muscle Spasms?
- What's the Strongest Muscle in the Human Body?
- Can Diabetes Cause Muscle Pain?
- How Muscles Work & Respond to Resistance Training
- Muscle Cramp (Charley Horse) Treatment and Symptoms
- Pain Relievers and High Blood Pressure
Medications & Supplements
- cyclobenzaprine - oral, Flexeril
- cyclobenzaprine (Flexeril, Amrix, Fexmid)
- Robaxin vs. Flexeril
- Baclofen vs. Flexeril (Side Effects and Interactions)
- Cyclobenzaprine (Flexeril) vs. amitriptyline (Elavil)
- Cyclobenzaprine (Flexeril) vs. carisoprodol (Soma)
- Cyclobenzaprine (Flexeril) vs. naproxen (Aleve)
- Cyclobenzaprine vs. Xanax (alprazolam)
- Cyclobenzaprine vs. Zanaflex
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.