Flexeril 5mg Tablets
It is used to relax muscles.
Drug Class
Skeletal Muscle Relaxant
Pharmacologic Class
Centrally Acting Skeletal Muscle Relaxant
Pregnancy Category
Category B
FDA Approved
Aug 1977
DEA Schedule
Not Controlled
Overview
What is this medicine?
Cyclobenzaprine is a medication used for short-term relief of muscle spasms, often caused by injuries. It works by relaxing your muscles and reducing pain. It's usually used along with rest and physical therapy.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the proper disposal method. You may also have access to drug take-back programs in your area.
Missing a Dose
If you take this medication on a regular schedule, take the missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your normal dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
To use this medication correctly, follow your doctor's instructions and read all the information provided. You can take this medication with or without food.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the proper disposal method. You may also have access to drug take-back programs in your area.
Missing a Dose
If you take this medication on a regular schedule, take the missed dose as soon as you remember. However, if it's close to the time for your next dose, skip the missed dose and resume your normal dosing schedule. Do not take two doses at the same time or take extra doses. If you take this medication as needed, do not take it more frequently than directed by your doctor.
Lifestyle & Tips
- Avoid driving or operating heavy machinery until you know how this medication affects you, as it can cause drowsiness and dizziness.
- Avoid alcohol and other CNS depressants (like sleeping pills or anxiety medications) while taking cyclobenzaprine, as this can increase drowsiness and other side effects.
- Take the medication exactly as prescribed by your doctor. Do not take more or less than directed.
- This medication is typically for short-term use (2-3 weeks). Do not use it for longer periods unless specifically advised by your doctor.
- To help with dry mouth, chew sugarless gum, suck on hard candy, or use saliva substitutes.
- To prevent constipation, increase fiber intake and drink plenty of fluids.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
5 mg orally three times daily
Dose Range:
5 - 10 mg
Condition-Specific Dosing:
muscleSpasm:
Initial: 5 mg orally three times daily. May increase to 10 mg orally three times daily based on individual response. Maximum recommended dose is 30 mg/day. Use for short periods (up to 2-3 weeks).
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (Safety and efficacy not established for patients younger than 15 years of age)
Adolescent:
Not established (Safety and efficacy not established for patients younger than 15 years of age)
Dose Adjustments
Renal Impairment:
Mild:
Use with caution; no specific dose adjustment recommended but monitor for increased adverse effects.
Moderate:
Use with caution; no specific dose adjustment recommended but monitor for increased adverse effects.
Severe:
Use with caution; no specific dose adjustment recommended but monitor for increased adverse effects.
Dialysis:
Not significantly removed by dialysis; use with caution and monitor for adverse effects.
Hepatic Impairment:
Mild:
Use with caution; consider lower initial dose (e.g., 5 mg once daily at bedtime) and titrate slowly.
Moderate:
Use with caution; consider lower initial dose (e.g., 5 mg once daily at bedtime) and titrate slowly.
Severe:
Contraindicated due to significantly increased plasma concentrations and half-life.
Pharmacology
Mechanism of Action
Cyclobenzaprine acts in the central nervous system at the brain stem level, primarily on the locus coeruleus, to reduce tonic somatic motor activity influencing both alpha and gamma motor neurons. It does not directly act on the muscle or neuromuscular junction. Its action is believed to be related to its ability to relieve muscle spasm of local origin without interfering with muscle function.
Pharmacokinetics
Absorption:
Bioavailability:
33-55%
Tmax:
4-6 hours
FoodEffect:
Food increases the extent of absorption and peak plasma concentration, but does not affect the time to peak concentration.
Distribution:
Vd:
10-30 L/kg (large volume of distribution)
ProteinBinding:
>90%
CnssPenetration:
Yes
Elimination:
HalfLife:
18 hours (range 8-37 hours)
Clearance:
Not available (highly variable)
ExcretionRoute:
Renal (primarily as metabolites), Fecal (small amount)
Unchanged:
<1%
Pharmacodynamics
OnsetOfAction:
Approximately 1 hour
PeakEffect:
3-8 hours
DurationOfAction:
12-24 hours
Confidence:
Medium
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek emergency medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Abnormal or fast heartbeat
Serotonin syndrome, a potentially life-threatening condition that may occur when taking this medication with certain other drugs. Watch for:
+ Agitation
+ Change in balance
+ Confusion
+ Hallucinations
+ Fever
+ Abnormal or fast heartbeat
+ Flushing
+ Muscle twitching or stiffness
+ Seizures
+ Shivering or shaking
+ Excessive sweating
+ Severe diarrhea
+ Upset stomach
+ Vomiting
+ Severe headache
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, contact your doctor if they bother you or do not go away:
Dizziness
Drowsiness
Fatigue
Weakness
Dry mouth
Constipation
Upset stomach
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek emergency medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Abnormal or fast heartbeat
Serotonin syndrome, a potentially life-threatening condition that may occur when taking this medication with certain other drugs. Watch for:
+ Agitation
+ Change in balance
+ Confusion
+ Hallucinations
+ Fever
+ Abnormal or fast heartbeat
+ Flushing
+ Muscle twitching or stiffness
+ Seizures
+ Shivering or shaking
+ Excessive sweating
+ Severe diarrhea
+ Upset stomach
+ Vomiting
+ Severe headache
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, contact your doctor if they bother you or do not go away:
Dizziness
Drowsiness
Fatigue
Weakness
Dry mouth
Constipation
Upset stomach
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe drowsiness or dizziness
- Confusion or hallucinations
- Fast or irregular heartbeat
- Chest pain
- Difficulty breathing or swallowing
- Swelling of the face, lips, tongue, or throat (signs of allergic reaction)
- Signs of serotonin syndrome: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness or twitching, loss of coordination, nausea, vomiting, diarrhea.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ Abnormal heart rhythms or heart block
+ Heart failure (a weakened heart)
+ Liver disease
+ An overactive thyroid gland
If you have recently had a heart attack
If you have taken specific medications for depression or Parkinson's disease within the last 14 days, such as:
+ Isocarboxazid
+ Phenelzine
+ Tranylcypromine
+ Selegiline
+ Rasagiline (note: taking these medications with this drug can lead to very high blood pressure)
If you are currently taking any of the following medications:
+ Linezolid
+ Methylene blue
This list is not exhaustive, and it is crucial to inform your doctor and pharmacist about all the medications you are taking, including:
Prescription medications
Over-the-counter (OTC) medications
Natural products
* Vitamins
Your doctor needs to be aware of all your medications and health conditions to ensure it is safe for you to take this medication. Do not start, stop, or change the dose of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ Abnormal heart rhythms or heart block
+ Heart failure (a weakened heart)
+ Liver disease
+ An overactive thyroid gland
If you have recently had a heart attack
If you have taken specific medications for depression or Parkinson's disease within the last 14 days, such as:
+ Isocarboxazid
+ Phenelzine
+ Tranylcypromine
+ Selegiline
+ Rasagiline (note: taking these medications with this drug can lead to very high blood pressure)
If you are currently taking any of the following medications:
+ Linezolid
+ Methylene blue
This list is not exhaustive, and it is crucial to inform your doctor and pharmacist about all the medications you are taking, including:
Prescription medications
Over-the-counter (OTC) medications
Natural products
* Vitamins
Your doctor needs to be aware of all your medications and health conditions to ensure it is safe for you to take this medication. Do not start, stop, or change the dose of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
When starting this medication, be cautious when driving or performing tasks that require alertness, as its effects on you are unknown. Wait until you understand how this drug affects you before engaging in such activities.
In hot weather or during physical activity, exercise caution to avoid dehydration. Drink plenty of fluids to prevent fluid loss.
Before consuming alcohol, using marijuana or other cannabis products, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
Adhere to your doctor's prescribed duration for taking this medication. Do not exceed the recommended treatment period.
This medication is typically used in conjunction with rest, physical therapy, pain management drugs, and other therapeutic interventions.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor. It is crucial to discuss the potential benefits and risks of this medication to both you and your baby.
When starting this medication, be cautious when driving or performing tasks that require alertness, as its effects on you are unknown. Wait until you understand how this drug affects you before engaging in such activities.
In hot weather or during physical activity, exercise caution to avoid dehydration. Drink plenty of fluids to prevent fluid loss.
Before consuming alcohol, using marijuana or other cannabis products, or taking prescription or over-the-counter medications that may cause drowsiness, consult with your doctor.
Adhere to your doctor's prescribed duration for taking this medication. Do not exceed the recommended treatment period.
This medication is typically used in conjunction with rest, physical therapy, pain management drugs, and other therapeutic interventions.
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor. It is crucial to discuss the potential benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Severe drowsiness
- Dizziness
- Fainting
- Vomiting
- Tachycardia (rapid heartbeat)
- Hypotension (low blood pressure)
- Tremors
- Agitation
- Coma
- Confusion
- Hallucinations
- Dilated pupils
- Slurred speech
- Ataxia (loss of coordination)
- Dysarthria (difficulty speaking)
- Cardiac arrest
What to Do:
Seek immediate medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222. Treatment is generally supportive, including gastric lavage, activated charcoal, and symptomatic management of cardiovascular and CNS effects.
Drug Interactions
Contraindicated Interactions
- Monoamine Oxidase Inhibitors (MAOIs) within 14 days (risk of hyperpyretic crisis, convulsions, death)
- Hyperthyroidism
- Congestive heart failure
- Arrhythmias
- Heart block or conduction disturbances
- Acute recovery phase of myocardial infarction
Major Interactions
- CNS Depressants (e.g., alcohol, barbiturates, benzodiazepines, opioids, other muscle relaxants): Additive CNS depression (drowsiness, dizziness, impaired coordination).
- Serotonergic Drugs (e.g., SSRIs, SNRIs, TCAs, tramadol, triptans, St. John's Wort): Risk of serotonin syndrome.
- Tricyclic Antidepressants (TCAs): Additive anticholinergic effects and CNS depression.
Moderate Interactions
- Anticholinergic Agents (e.g., atropine, scopolamine, some antihistamines): Additive anticholinergic effects (dry mouth, blurred vision, urinary retention, constipation).
- Guanethidine and similar acting compounds: May block the antihypertensive effect.
- Tramadol: Increased risk of seizures and serotonin syndrome.
- Meperidine: Increased risk of serotonin syndrome.
Minor Interactions
- Not available (most interactions are moderate to major due to CNS or anticholinergic effects)
Monitoring
Baseline Monitoring
Medical History (especially cardiovascular, thyroid, and psychiatric conditions)
Rationale: To identify contraindications (e.g., heart block, hyperthyroidism, MAOI use) and assess risk for adverse effects (e.g., CNS depression, anticholinergic effects).
Timing: Prior to initiation of therapy
Medication Reconciliation
Rationale: To identify potential drug-drug interactions, especially with CNS depressants, serotonergic drugs, and anticholinergic agents.
Timing: Prior to initiation of therapy
Routine Monitoring
Efficacy (reduction in muscle spasm, pain, improved range of motion)
Frequency: Daily to weekly during short-term use
Target: Subjective improvement in symptoms
Action Threshold: Lack of improvement or worsening symptoms after 2-3 weeks indicates need to discontinue or re-evaluate therapy.
Adverse Effects (drowsiness, dizziness, dry mouth, constipation, blurred vision)
Frequency: Daily, especially during initial therapy
Target: Absence or mild, tolerable symptoms
Action Threshold: Severe or intolerable adverse effects warrant dose reduction or discontinuation.
Mental Status/CNS Depression
Frequency: Daily, especially during initial therapy or with concomitant CNS depressants
Target: Alertness appropriate for activity; no excessive sedation or confusion
Action Threshold: Significant sedation, confusion, or impaired coordination warrants dose reduction or discontinuation.
Symptom Monitoring
- Drowsiness
- Dizziness
- Dry mouth
- Constipation
- Blurred vision
- Fatigue
- Nausea
- Headache
- Urinary retention
- Confusion
- Agitation (especially in elderly)
- Signs of serotonin syndrome (e.g., agitation, hallucinations, rapid heart beat, fever, overactive reflexes, nausea, vomiting, diarrhea, uncoordinated movements)
Special Patient Groups
Pregnancy
Cyclobenzaprine is Pregnancy Category B. Animal studies have not shown harm to the fetus, but there are no adequate and well-controlled studies in pregnant women. Use only if clearly needed.
Trimester-Specific Risks:
First Trimester:
Low risk based on animal data, but human data is limited. Use only if benefits outweigh potential risks.
Second Trimester:
Low risk based on animal data, but human data is limited. Use only if benefits outweigh potential risks.
Third Trimester:
Low risk based on animal data, but human data is limited. Potential for neonatal withdrawal symptoms or CNS depression if used close to delivery, though not well-documented for cyclobenzaprine specifically.
Lactation
It is not known whether cyclobenzaprine is excreted in human milk. However, it is excreted in the milk of lactating rats. Due to the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
Risk is unknown but potential for sedation and anticholinergic effects in the infant. Monitor infant for drowsiness, poor feeding, and unusual behavior. L3 (Moderately Safe) to L4 (Potentially Hazardous) depending on source and interpretation.
Pediatric Use
Safety and efficacy have not been established for patients younger than 15 years of age. Not recommended for use in this population.
Geriatric Use
Elderly patients are more susceptible to adverse effects such as drowsiness, dizziness, confusion, and anticholinergic effects (e.g., dry mouth, constipation, urinary retention). Start with a lower dose (e.g., 5 mg once daily at bedtime) and titrate slowly. Avoid use in elderly if possible, or use with extreme caution and monitor closely.
Clinical Information
Clinical Pearls
- Cyclobenzaprine is intended for short-term use (2-3 weeks) for acute muscle spasm, not for chronic pain or spasticity.
- Due to its sedative effects, it is often prescribed to be taken at bedtime, especially the initial dose.
- Warn patients about the potential for significant drowsiness and dizziness, and advise against driving or operating machinery.
- Educate patients about the risk of serotonin syndrome when combined with other serotonergic drugs.
- Avoid in patients with a history of cardiac arrhythmias, heart block, or recent MI due to its structural similarity to tricyclic antidepressants.
- Consider alternative therapies like NSAIDs, acetaminophen, or physical therapy for muscle pain before resorting to muscle relaxants, or use them adjunctively.
Alternative Therapies
- Other centrally acting skeletal muscle relaxants (e.g., Tizanidine, Methocarbamol, Metaxalone, Carisoprodol, Baclofen)
- Nonsteroidal Anti-inflammatory Drugs (NSAIDs) (e.g., Ibuprofen, Naproxen)
- Acetaminophen
- Physical therapy
- Heat/cold therapy
- Massage
Cost & Coverage
Average Cost:
$10 - $30 per 30 tablets (generic 5mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic) or Tier 2 (Preferred Brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further evaluation and guidance. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may have additional patient information leaflets, so it is a good idea to consult with your pharmacist for more information. If you have any questions or concerns about this medication, do not hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When reporting the overdose, be prepared to provide details about the medication taken, the amount, and the time it occurred.