Flexeril

Generic name: cyclobenzaprine
Brand names: Amrix, Fexmid, Flexeril
Drug class: Skeletal muscle relaxants

Medically reviewed by  A Ras MD.

What is Flexeril used for?

Flexeril is a prescription medicine that is used used to relax muscles.

Dsesxription

Cyclobenzaprine hydrochloride is a white, crystalline tricyclic amine salt with the empirical formula C20H21N•HCl and a molecular weight of 311.9. It has a melting point of 217°C, and a pKa of 8.47 at 25°C. It is freely soluble in water and alcohol, sparingly soluble in isopropanol, and insoluble in hydrocarbon solvents. If aqueous solutions are made alkaline, the free base separates. Cyclobenzaprine HCl is designated chemically as 3-(5H-dibenzo[a,d] cyclohepten-5-ylidene)-N, Ndimethyl- 1-propanamine hydrochloride, and has the following structural formula:

 

FLEXERIL

 

FLEXERIL 5 mg (Cyclobenzaprine HCl) is supplied as a 5 mg tablet for oral administration. FLEXERIL 10 mg (Cyclobenzaprine HCl) is supplied as a 10 mg tablet for oral administration.

FLEXERIL tablets contain the following inactive ingredients: hydroxypropyl cellulose, hydroxypropyl methylcellulose, iron oxide, lactose, magnesium stearate, starch, and titanium dioxide. FLEXERIL 5 mg tablets also contain Yellow D&C #10 Aluminum Lake HT, and Yellow FD&C #6 Aluminum Lake.

Before taking Flexeril, tell your doctor:

  • If you are allergic to Flexeril; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you have any of these health problems: Heart block or other heartbeat that is not normal, heart failure (weak heart), liver disease, or an overactive thyroid gland.
  • If you have had a recent heart attack.
  • If you have taken certain drugs for depression or Parkinson’s disease in the last 14 days. This includes isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline. Very high blood pressure may happen.
  • If you are taking any of these drugs: Linezolid or methylene blue.

This is not a list of all drugs or health problems that interact with this medicine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take Flexeril with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Flexeril?

  • Tell all of your health care providers that you take Flexeril. This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how Flexeril affects you.
  • Be careful in hot weather or while being active. Drink lots of fluids to stop fluid loss.
  • Talk with your doctor before you drink alcohol or use other drugs and natural products that slow your actions.
  • Do not take Flexeril for longer than you were told by your doctor.
  • This medicine is used with rest, PT (physical therapy), pain drugs, and other therapies.
  • If you are 65 or older, use Flexeril with care. You could have more side effects.
  • Tell your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding. You will need to talk about the benefits and risks to you and the baby.

How is Flexeril best taken?

Use Flexeril as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Take with or without food.

What do I do if I miss a dose?

  • If you take Flexeril on a regular basis, take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.
  • Many times Flexeril is taken on an as needed basis. Do not take more often than told by the doctor.

What are the side effects of Flexeril that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like 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; or swelling of the mouth, face, lips, tongue, or throat.
  • A fast heartbeat.
  • A heartbeat that does not feel normal.
  • A severe and sometimes deadly problem called serotonin syndrome may happen if you take Flexeril with certain other drugs. Call your doctor right away if you have agitation; change in balance; confusion; hallucinations; fever; fast or abnormal heartbeat; flushing; muscle twitching or stiffness; seizures; shivering or shaking; sweating a lot; severe diarrhea, upset stomach, or throwing up; or severe headache.

What are some other side effects of Flexeril?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Drug Interactions

A total of 392 medications are known to interact with Flexeril. Use the Interactions Checker Tool.

Common Interactions Checks

  • Cymbalta
  • gabapentin
  • ibuprofen
  • lisinopril
  • Lyrica
  • metformin
  • Norco
  • omeprazole
  • tramadol
  • trazodone
  • Vitamin D3
  • Xanax

How do I store and/or throw out Flexeril?

  • Store at room temperature.
  • Protect from light.
  • Store in a dry place. Do not store in a bathroom.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

 

SRC: NLM .