Cyclobenzaprine Hydrochloride

What is Cyclobenzaprine Hydrochloride?

Cyclobenzaprine hydrochloride is a prescription muscle relaxant that is used for short-term relief of muscle spasm. It has been sold under brand names such as Flexeril and Amrix, and it is widely available as generic medicine.

Drug class

Cyclobenzaprine belongs to the group of medicines called centrally acting skeletal muscle relaxants. It is chemically related to tricyclic antidepressants, which helps explain some of its side effects, such as drowsiness and dry mouth.

Approved and common prescribed uses

Cyclobenzaprine is approved by the U.S. FDA as an add-on treatment, together with rest and physical therapy, for relief of muscle spasm linked to acute, painful musculoskeletal conditions, such as:

• Muscle strains and sprains
• Acute low back pain with muscle spasm
• Neck pain with muscle spasm

It is not approved for muscle spasm caused by diseases of the brain or spinal cord, or for cerebral palsy. Providers sometimes prescribe it for other conditions, such as fibromyalgia, based on clinical judgment. It is not meant for long-term use.

Available formulations and strengths

Strengths and products vary by country and brand, so check your package.

• Immediate-release tablets (commonly Cyclobenzaprine Hydrochloride 5mg)
• Extended-release capsules (Cyclobenzaprine hydrochloride 15mg ER)

Immediate-release and extended-release forms do not work the same way, so do not switch between them unless your provider tells you to.

What is the Recommended Dosage of Cyclobenzaprine Hydrochloride?

The right dose is not the same for everyone. Your healthcare provider decides the dose based on:

• Condition: the type and severity of muscle spasm
• Age: older adults are usually started with a lower dose or advised to avoid the medicine
• Liver function: people with liver impairment may need a lower dose, and the extended-release form is not recommended in moderate to severe liver impairment
• Other medicines: some medicines raise the risk of serious reactions when combined with cyclobenzaprine

Available dosage forms

Immediate-release tablets and extended-release capsules, as listed above.

Important dosing points

• Follow the instructions from your licensed medical specialist and the directions on the label.
• Tablets are usually taken a few times a day, and extended-release capsules are usually taken once a day, at about the same time each day, as your provider directs.
• Swallow extended-release capsules whole. Do not crush or chew them.
• The medicine can be taken with or without food.
• Treatment is meant to be short. Using it for longer than two to three weeks is generally not advised, since there is little proof that it helps beyond that time and the risk of side effects continues. See your provider if symptoms continue.
• Combine the medicine with rest, gentle movement, and physical therapy as your provider recommends.

How Cyclobenzaprine Hydrochloride Works

Cyclobenzaprine acts mainly in the brain stem rather than directly on the muscles. It appears to reduce the nerve signals that cause muscles to tighten by affecting certain chemical messengers such as serotonin and norepinephrine. It also has a calming (sedative) effect, which may help with rest and sleep while muscles are sore.

Cyclobenzaprine helps manage the symptoms of muscle spasm and pain. It does not heal the injured muscle or treat the underlying cause of the pain.

Is a Prescription Required to Buy Cyclobenzaprine Hydrochloride Online?

Yes. Cyclobenzaprine is a prescription-only medicine in the United States and in most other countries.

• Talk with a licensed medical specialist before using it. Depending on your condition, this may be an orthopedic doctor, a physical medicine and rehabilitation (rehab) specialist, a pain management specialist, or your primary care physician.
• Buy only from licensed, verified pharmacies that ask for a valid prescription.
• Be careful of counterfeit or substandard products. Signs include damaged packaging, missing batch numbers or expiry dates, spelling errors, and unusual tablet or capsule appearance.
• Do not buy from websites that offer the medicine without a prescription or that cannot show pharmacy licensing details.

Side Effects of Cyclobenzaprine Hydrochloride

Many people have side effects, especially when starting the medicine.

Common side effects

• Drowsiness or sleepiness
• Dry mouth
• Dizziness or lightheadedness
• Tiredness or weakness
• Constipation
• Blurred vision
• Nausea, upset stomach, or an unpleasant taste
• Headache

Tell your provider if these effects continue or bother you.

Serious side effects

Serious reactions are uncommon but need prompt care. Stop the medicine and get medical help right away if you notice:

• Agitation, confusion, fever, sweating, shivering, fast heartbeat, muscle stiffness or twitching, or severe diarrhea (possible serotonin syndrome)
• A fast, pounding, or irregular heartbeat, chest pain, or fainting
• Swelling of the face, lips, tongue, or throat, wheezing, trouble breathing, or a widespread rash (possible severe allergic reaction)
• Seeing or hearing things that are not there, or severe confusion
• Seizures
• Difficulty passing urine
• Yellowing of the skin or eyes, or dark urine
• Eye pain or sudden vision changes

If you are unsure whether a symptom is serious, contact a healthcare provider or local emergency service.

Drug Interactions

Tell your licensed medical specialist and pharmacist about every medicine you take. Major interaction categories include:

• MAOI antidepressants (such as phenelzine, tranylcypromine, selegiline, and linezolid): must not be taken with cyclobenzaprine or within 14 days after stopping an MAOI, because of a risk of a dangerous reaction.
• Serotonergic medicines (such as SSRIs, SNRIs, tricyclic antidepressants, tramadol, meperidine, triptans, buspirone, and St. John’s wort): raise the risk of serotonin syndrome.
• Alcohol, sedatives, sleeping pills, anti-anxiety medicines, opioids, and other muscle relaxants: may add to drowsiness and slowed breathing.
• Anticholinergic medicines (such as some antihistamines, bladder medicines, and medicines for Parkinson’s disease): may add to dry mouth, constipation, blurred vision, and trouble passing urine.
• Some blood pressure medicines, especially those that act in the nervous system, such as clonidine and guanethidine-type medicines: cyclobenzaprine may reduce their effect.
• Medicines that affect heart rhythm: may add to effects on the heart.

Over-the-counter medicines, supplements, and herbal products

Sleep aids, cold and allergy products that cause drowsiness, and herbal products such as St. John’s wort, valerian, and kava may add to sleepiness or raise the risk of serotonin syndrome. Give your provider a complete, up-to-date list of prescription medicines, over-the-counter products, vitamins, supplements, and herbal remedies.

Safety & Important Considerations

• Serotonin syndrome: This rare but serious reaction can happen, especially when cyclobenzaprine is combined with other medicines that raise serotonin. Know the warning signs and get care right away if they appear.
• Heart: Cyclobenzaprine can affect heart rhythm and heart conduction, and it is not suitable for people with certain heart conditions. Use caution in anyone with a history of heart disease.
• Sleepiness: The medicine often causes drowsiness. Avoid driving, operating machinery, or other tasks that need alertness until you know how it affects you. Avoid alcohol.
• Eyes and bladder: Because of its anticholinergic effects, use caution in people with glaucoma (high eye pressure), an enlarged prostate, or trouble passing urine.
• Liver: Use caution in liver disease. Lower doses or a different medicine may be needed.
• Thyroid: Not suitable for people with an overactive thyroid.
• Seizures: Use caution in people with seizure disorders.
• Pregnancy: Safety data in pregnancy are limited. Talk to your provider before using it at any stage of pregnancy or if you are trying to conceive.
• Breastfeeding: It is not clear how much passes into breast milk. Ask your provider before use.
• Children: Safety and effectiveness in children under 15 have not been established, and the extended-release form is not meant for children. Use in children should be directed by a specialist.
• Older adults: Cyclobenzaprine is on a widely used list of medicines that older adults should generally avoid or use with great caution because of the risk of confusion, falls, and anticholinergic effects. If prescribed, lower doses and closer monitoring may be needed.
• Short-term use: Use only for the planned length of time. If pain lasts beyond a few weeks, ask your provider to look for other causes and treatments.

Who This Medication Is For

Cyclobenzaprine is typically used by adults and adolescents who are old enough for the medicine under a provider’s direction and who have short-term, painful muscle spasm, such as a strain, sprain, or back or neck spasm, as part of a plan that also includes rest and physical therapy. Whether it is suitable for you depends on your medical history, your other medicines, and your specialist’s assessment.

Who Should Not Take Cyclobenzaprine Hydrochloride

Do not take this medicine if you:

• Are allergic to cyclobenzaprine or any ingredient in the product
• Are taking an MAOI, or stopped taking one within the last 14 days
• Are in the early recovery period after a heart attack
• Have a heart rhythm disorder, heart block, or other heart conduction problem
• Have heart failure
• Have an overactive thyroid (hyperthyroidism)

Use extra caution and speak with your provider first if you have glaucoma, an enlarged prostate or trouble urinating, liver disease, a seizure disorder, a history of drug or alcohol misuse, or if you are an older adult.

What to Do If You Miss a Dose

• Take the missed dose as soon as you remember.
• If it is almost time for your next dose, skip the missed one and continue your normal schedule.
• Do not take two doses at once to make up for a missed dose.
• If you are unsure what to do, contact your licensed medical specialist or pharmacist.

If you think you have taken too much, seek medical help immediately, even if you feel well. Overdose can cause severe drowsiness, a fast or irregular heartbeat, seizures, and coma, and it can be life-threatening.

Related medications to Cyclobenzaprine Hydrochloride

Other options in the same general therapeutic area may include:

• Other muscle relaxants for short-term muscle spasm, such as methocarbamol, metaxalone, tizanidine, or baclofen
• NSAIDs, such as ibuprofen or naproxen
• Paracetamol (acetaminophen) for pain
• Topical pain relievers, such as NSAID gels or heat patches
• Non-drug approaches such as heat or cold, gentle stretching, physical therapy, and staying active as advised

The best option depends on your condition, health history, and other medicines. Do not switch, combine, or stop treatments on your own. Any change should be discussed with a licensed medical specialist.

Storage Instructions

• Store at room temperature, generally between 20°C and 25°C (68°F to 77°F), unless the package says otherwise.
• Keep in the original container, tightly closed, to protect from moisture and light.
• Avoid storing in bathrooms or other damp places.
• Keep out of the sight and reach of children and pets.
• Do not use after the expiry date. Ask a pharmacist how to dispose of unused or expired medicine safely.

Disclaimer:

This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Patients must consult a licensed orthopedic specialist, physical medicine and rehabilitation specialist, or other relevant medical specialist before starting, changing, or stopping treatment. Treatment decisions must be based on a full clinical evaluation by a qualified specialist.