Cyclobenzaprine is a medication known as a skeletal muscle relaxant that is often prescribed to help relax muscles and ease pain due to sprains, strain, and other muscle-related issues. The brand names for cyclobenzaprine are Amrix,Fexmid, and Flexeril.

Cyclobenzaprine is usually prescribed as a short-term treatment along with physical therapy and rest. It acts on the central nervous system (CNS) to help the muscles feel relaxed. It’s available in several forms including a tablet, an extended release capsule, and as a suspension.

Some off-label uses for cyclobenzaprine include tension headaches and migraines, insomnia, tinnitus and pain and muscle spasms caused by fibromyalgia.

Skeletal and muscle relaxant use in the United States is ongoing, and it is estimated that about 2 million people are taking them, per this medical study. The study authors concluded that muscle relaxants, like cyclobenzaprine, are chronically used and prescribed for some people who could be adversely affected by the medicine.

Precautions to Know When Taking Cyclobenzaprine

Many medications may interact with cyclobenzaprine. Be sure to let your doctor know about any other prescription medications, drugs, or supplements you are taking. Don’t make any changes to your dosage or dosing schedule without speaking with your doctor first.

Some medical conditions may affect cyclobenzaprine use. Let your doctor know if you have any medical conditions, especially heart problems, hyperthyroidism, glaucoma, a history of urinary trouble, and liver disease.

If you are prescribed this medicine, it is best not to drink any alcohol. Alcohol and cyclobenzaprine taken together might result in hazardous side effects. If you feel you need to have a drink now and then when on this medication, please consult with your doctor.

It is possible to use too much of this medicine and experience symptoms of serotonin syndrome, which can be hazardous to your health. The symptoms include:


  • Fever
  • Sweating
  • Shivering
  • Agitation
  • Fast heart rate
  • Hallucinations
  • Muscle stiffness
  • Twitching
  • Nausea and/or vomiting
  • Diarrhea
  • Loss of coordination

Serotonin syndrome is a condition that should not be taken lightly. Some symptoms may be mild, while others can be severe and cause death,  according to the Mayo Clinic

Although addiction to cyclobenzaprine isn’t as common as addiction to some other drugs, it can still occur. Overdose may also occur. Taking too much cyclobenzaprine can result in an overdose, which can be dangerous or even deadly. It’s important to follow prescription instructions carefully.

Side Effects of Flexeril

Every prescription drug causes side effects, some of which can be mild and others more serious. These are the possible side effects of Flexeril and cyclobenzaprine:

  • Tiredness
  • Drowsiness
  • Upset stomach
  • Headache
  • Dizziness
  • Dry mouth
  • Upset stomach
  • Nausea
  • Constipation

Older adults might be more likely to feel these side effects more intensely. If you find any side effects too much to bear, please contact the prescribing physician for a consultation. It is always wise to talk with the doctor before stopping the use of any prescription medicine.

How Much Cyclobenzaprine Is Too Much?

The standard dosage for cyclobenzaprine will vary depending on the form of the medication and whether the patient is an adult or a child. For adults and children 15 years old and older, in most cases, the dose for an extended-release capsule will be between 15 mg (milligrams) to 30 mg per day.

For tablets, the dose for adults and children over 15 years old is usually 10 mg taken three times a day, with a maximum dose of 60 mg per day. Dosages for children under 15 years old must be established by your healthcare professional. Taking more than the recommended dosage of cyclobenzaprine may result in an overdose.

Cyclobenzaprine should only be taken for two to three weeks and not longer. The recommended dose on the prescription is the amount to take. If you are wondering how much cyclobenzaprine is too much, then you are considering misusing the drug for purposes other than what it is prescribed for.

It’s best to avoid drinking alcohol or other drugs that depress the central nervous system, including:

  • Benzodiazepines like Valium and Xanax and other sedatives
  • Antihistamines
  • Sleep medications
  • Tranquilizers
  • Prescription pain medications
  • Seizure medication or barbiturates
  • Additional muscle relaxers
  • Anesthetics including anesthetics for dental procedures

Drinking alcohol or taking other CNS depressants can increase the chances of dangerous side effects or overdose.

How to Recognize a Cyclobenzaprine Overdose

A question that often arises when people are taking this drug is, “Can you OD on cyclobenzaprine?” The answer is yes, it is possible to take too much of this drug and its brand name equivalent and experience a Flexeril overdose.

Several signs and symptoms can indicate a cyclobenzaprine overdose. Cyclobenzaprine affects the central nervous system (CNS). Taking more than the prescribed dose may result in some very serious, and potentially deadly, symptoms.

If you think someone has overdosed on cyclobenzaprine, call 911 or get emergency medical help right away.

Symptoms of a cyclobenzaprine overdose may include:

  • Agitation
  • Change in body temperature
  • Confusion
  • Dizziness
  • Drowsiness
  • Rapid or irregular heartbeat
  • Trouble with speech or movement
  • Nausea
  • Vomiting
  • Hallucinations
  • Tremors
  • Loss of consciousness
  • Heart attack (rare)
  • Seizures (rare)

Dangers of a Cyclobenzaprine Overdose

If you observe someone who has overdosed on cyclobenzaprine, or may have taken a Flexeril lethal dose, call 911 immediately. 

A cyclobenzaprine overdose can be dangerous and even deadly. Taking too much of it can cause an irregular heartbeat, vomiting, hallucinations, seizures, or even death.

It’s very important to take only the prescribed dose provided by your doctor. If you have any questions about your prescription or dosage, contact your doctor. Don’t make any changes in your dosage without talking with your doctor first.

Also, always be sure that this medication and any other medications, drugs, or supplements are out of the reach of children. In fact, accidental overdose is a leading cause of death for children ages 6 months to 5 years old.

Have the local poison control center information handy if you have small children in your household or locate one by dialing 800-222-1222 or accessing the American Association of Poison Control Centers (

What to do While Waiting For the Paramedics

After you call 911, stay with the victim and remain calm. Make sure they are breathing and help them stay conscious.

First, quickly remove any objects from around the victim. If they have a seizure, clearing the space will help limit the possibility of injury.

Make sure you check on the victim’s breathing. Once you have cleared the space around them, tilt their head back. This keeps the airway open. If their breathing becomes shallow or they stop breathing, then tilt their head back and gently lift their chin. Close their nostrils shut, and then seal your mouth over their lips.

After you have sealed your mouth over theirs, quickly blow two breaths into their mouth. At each 5-second mark, give them a long breath.

Do not give any beverages or food to the victim. This could cause them to choke.

Make sure they stay awake.

Don’t move the victim or put them in the shower. This could cause shock. Relay any information about the individual to the paramedics that can help them better treat the person, such as if they consumed any alcohol, took any other drugs, or have a history of substance use or mental health disorders. 

Cyclobenzaprine Overdose Treatment

While it is not common that you or someone you may know become addicted to this medication, it is possible to overdose on cyclobenzaprine. Addiction to prescription drugs is not uncommon, and mental health disorders are usually an underlying reason why one abuses drugs. The National Institute on Drug Abuse (NIDA) reports that a little more than 16 million people said they had misused prescription drugs in the last month in 2020.

Cyclobenzaprine overdose treatment will vary depending on the amount of the overdose. The larger the overdose and the more serious the symptoms, the longer and more intense the treatment will be.

The victim may require CPR if they are not breathing. If they continue to have trouble breathing or have an irregular heartbeat, then oxygen and defibrillation may also be necessary.

A medication known as syrup of ipecac may be administered to induce vomiting. If this is not successful or doesn’t result in the removal of enough of the medication, the medical team may use a procedure called gastric lavage (“stomach pumping”) to mechanically remove the remaining medication from the stomach.

Activated charcoal may also be used to help limit how much of the medication is absorbed into the bloodstream. The drug binds to the charcoal and then is eliminated through the stool.

If the overdose is severe, a breathing tube may be inserted into the patient’s throat, and they may be monitored in the ICU for a few days. They may also require a medical detox and treatment for cyclobenzaprine withdrawal symptoms if they have been taking larger doses of the drug for a longer period.

The medical staff will continue to monitor the patient’s physical and mental health. Before discharge from the hospital, a psychiatric evaluation may be given, especially if the overdose was due to a suicide attempt.


If you or someone you love has a prescription for cyclobenzaprine (also known as the brand names Amrix or Fexmid), be sure to follow the dosing instructions carefully. If your condition changes, contact your doctor. Be sure you know how to recognize the signs and symptoms of a cyclobenzaprine overdose. If you witness someone who has overdosed on cyclobenzaprine, call 911 right away. Stay with the victim until help arrives and make sure they stay awake and remain breathing.

Cyclobenzaprine Addiction Treatment Near You

The Palm Beach Institute is an accredited mental health and substance use disorder treatment facility located in the Palm Beach, Florida, area. Our licensed medical and addiction professionals have helped people overcome drug abuse and set them on a solid course of sobriety, many for life. No matter which stage of recovery you are engaged in, our experienced care teams allow you your dignity, respect you as a person, and will be by your side throughout your journey. 

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