Flexeril (Cyclobenzaprine) Dosage and Side Effects
FLEXERIL is a muscle relaxer that relieves pain and discomfort caused by strains, sprains, and other muscle injuries.
Proper Use of this medication
Your doctor is likely to start you on 5 milligrams of the regular release tablet, three times a day.
The extended-release tablet is dosed once a day. This dose could be increased if you aren't getting relief from pain.
This drug is not meant to be taken long-term. Studies show it decreases pain for the first two weeks, peaking in the first few days but has no proven benefit after that.
Don't take this drug for more than three weeks without talking to your physician.
Patients with liver problems or who are over 65 years old may start at lower doses.
Always take FLEXERIL with a full glass of water and always swallow the medication whole.
Symptoms of FLEXERIL overdose include:
- Chest pain
- Rapid heartbeat
- Slurred speech
If you suspect an overdose, seek emergency medical attention or call a poison-control help line.
Missed Dose of FLEXERIL
Take the missed dose of FLEXERIL as soon as you remember.
Skip the missed dose if it is almost time for your next scheduled dose.
Don't “double up” on this medication to make up for a missed dose.
Common side effects of FLEXERIL include:
- Dry mouth
Let your physician know if any of these side effects persist or get worse.
Serious side effects of FLEXERIL include:
- Fast or irregular heartbeat
- Mood or mental changes (like confusion or hallucinations)
- Trouble urinating
- Chest pain
A very serious allergic reaction is rare but seek immediate medical attention if you develop any of the following:
- Swelling (especially in the face, tongue, or throat)
- Severe dizziness
- Trouble breathing
Combining this drug with some antidepressant medications could lead to serotonin syndrome and can be fatal. Symptoms of serotonin syndrome include:
- Agitation or restlessness
- Dilated pupils
- Changes in blood pressure
- Changes in body temperature
- Nausea or vomiting
- Severe diarrhea
- Rapid heart rate
- Loss of muscle coordination or twitching
- Shivering or goosebumps
- Heavy sweating
Interactions with this medication
Taking FLEXERIL with a MAOI can cause a life-threatening reaction.
In at least one clinical study, the risk of serotonin syndrome (excessive serotonin in the brain leading to a potentially fatal combination of symptoms) occurred in patients that mixed FLEXERIL with serotonergic drugs like duloxetine (Cymbalta).
FLEXERIL can also interact with central nervous system (CNS) depressants like opioids, benzodiazepines, nonbenzodiazepines, phenothiazines, certain chemotherapies, and barbiturates.
Tricyclic antidepressants, like amitriptyline (Elavil) and imipramine (Tofranil), combined with FLEXERIL can also increase the chance of side effects.
Alcohol and FLEXERIL
This medication can make you drowsy. Drinking alcohol could increase this effect.
For your safety, avoid drinking alcohol while taking FLEXERIL.
Warnings and Precautions
Don't take FLEXERIL if you've taken a monoamine oxidase inhibitor (MAOI) in the last two weeks. MAOIs, used to treat depression and Parkinson's disease, include:
- Isocarboxazid (Marplan)
- Linezolid (Zyvox)
- Phenelzine (Nardil)
- Rasagiline (Azilect)
- Selegiline (Emsam)
- Tranylcypromine (Parnate)
The combination of an MAOI with FLEXERIL can produce very serious, potentially life-threatening side effects.
Do not take this drug if you have a history of heart problems, including a previous heart attack, heart rhythm problems, blockages, or congestive heart failure.
People who are 65 years and older should not take this drug because the side effects can be more extreme. There are other medications that can be used to treat your condition that are safer and more effective if you are in this age group.
Patients with hepatic impairment (liver failure) are generally more susceptible to drugs with potentially sedating effects like FLEXERIL.
Tell your doctor if you are on any medication for depression, seizures, allergies, coughs, or colds, or if you take sedatives, sleeping pills, tranquilizers, or vitamins.
Before prescribing this medication, your healthcare provider should also know if you've ever been diagnosed with overactive thyroid, glaucoma, or if you've ever had difficulty urinating.
You should always tell your healthcare professional about all prescription, non-prescription, over-the-counter, illegal and recreational drugs, herbal remedies, nutritional and dietary supplements, and any other drugs and treatments.
FLEXERIL “High” and Abuse
Numerous online and anecdotal reports suggest that some people abuse FLEXERIL for a narcotic-like "high" because it can cause drowsiness.
FLEXERIL can induce moderate to severe anticholinergic effects — meaning, it may disrupt the activity of certain neurotransmitters in your brain — at higher doses. This can lead to physical and mental impairment.
At even higher doses, FLEXERIL may cause severe ataxia, a neurologic condition in which you lose control of your muscle movements.
Take FLEXERIL only as directed by your doctor, and keep this and all other drugs away from children, teenagers, and anyone for whom the drug was not prescribed.
Pregnancy and FLEXERIL
Discuss a current or planned pregnancy with your doctor before taking FLEXERIL.
This drug should only be taken during pregnancy if the benefits outweigh the risks. Your doctor can help you decide if it's right for you.
Also tell your physician if you're breastfeeding or plan to in the future. It's not known if FLEXERIL passes into breast milk, but studies show it has happened with similar drugs.
Other related products
The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.