By Edmund Murphy

Last updated: 15 November 2023 & medically reviewed by Dr. Celeste Small

Flexeril is the brand name of Cyclobenzaprine hydrochloride and is used as a muscle relaxant to treat sprains, tears, aches, and muscle spasms. If abused in high doses or for long periods of time it can lead to dependence and addiction.

Key takeaways:

  • Flexeril will often be prescribed in conjunction with a course of physio or physical therapy to repair damaged muscles, as well as rest. In some cases, Flexeril has been prescribed as a skeletal muscle relaxant used to treat musculoskeletal disorders such as arthritis and fibromyalgia
  • Since it may cause drowsiness/dizziness it is recommended to avoid drinking alcohol or other CNS depressants at the same time. It may impair the ability of a person to operate heavy machinery or drive safely
  • Flexeril produces a range of anticholinergic effects on the brain’s neurotransmitters which create relaxing or mildly euphoric effects. Cyclobenzaprine addiction can cause decreased mucus production in the nose and throat and a complaint of a constant sore throat

What is Cyclobenzaprine (Flexeril)?

Cyclobenzaprine (Cyclobenzaprine hydrochloride), sold under the brand name Flexeril, is a muscle relaxer similar to tricyclic antidepressants. Available in both immediate and extended-release versions as prescription medication, Flexeril is often prescribed to those suffering from short-term pain or discomfort relating to muscle injuries such as sprains, tears, muscle spasms, and aches.

It works by blocking pain receptors in the central nervous system (CNS) and can reduce muscle cramps, spasms, and pain caused by damaged muscles. Flexeril has a clinical response similar to benzodiazepines like diazepam (Valium). It is structurally related to cyclic antidepressants, and its pharmacologic effects are similar.

Flexeril will often be prescribed in conjunction with a course of physio or physical therapy to repair damaged muscles, as well as rest. In some cases, Flexeril has been prescribed as a skeletal muscle relaxant used to treat musculoskeletal disorders such as arthritis and fibromyalgia. It has an onset of action within an hour but can have a long half-life, staying in your system for over 30 hours. It is meant to be used for only 2-3 weeks at a time.

Effects of Cyclobenzaprine abuse

Taking Flexeril in the recommended dosage can help improve sleep patterns, raise energy levels, increase motor functions, and pain relief. Flexeril does not produce any euphoric feelings or notable highs when abused but the muscle relaxant nature of the drug may cause people to take more than the recommended dosage.

Flexeril misuse can have adverse effects that are harmful to a person’s health, such as:

  • Drowsiness

  • Dry mouth

  • Fatigue

  • Headaches

  • Dizziness

  • Nausea

  • Constipation

  • Blurred vision

  • Confusion

  • Acid reflux

  • Abdominal pain

  • Fever

  • Nervousness

  • Urination problems

  • Liver disease

Since it may cause drowsiness/dizziness it is recommended to avoid drinking alcohol or other CNS depressants such as opioids or benzodiazepines at the same time. It may impair the ability of a person to operate heavy machinery or drive safely.

Flexeril overdose

Another potential side effect of Flexeril abuse is cyclobenzaprine overdose, especially if taken in conjunction with other substances such as other CNS depressants like alcohol. Flexeril causes the body to become relaxed and abusing the substance in high doses can lead to cardiac arrest, low blood pressure, heart attack, and fatal seizures. Signs someone is having a Flexeril overdose include vomiting, slurred speech, rapid heartbeat, hallucinations, and difficulty breathing.

Related: Is Flexeril a controlled substance?

Is Flexeril addictive?

Flexeril produces a range of anticholinergic effects on the brain’s neurotransmitters which create relaxing or mildly euphoric effects. Cyclobenzaprine addiction can cause decreased mucus production in the nose and throat and a complaint of a constant sore throat. When Flexeril is abused a person may develop a dependence.

The potential for abuse and physical dependence is heightened if Flexeril is used regularly with other drugs that have a high potential for abuse and addiction such as alcohol and benzodiazepines. When someone gets into a cycle of mixing drugs to get high, also known as polydrug use, the chances of physical and psychological damage, such as depression and overdose, are heightened as is the likelihood of addiction-forming.

As Flexeril is readily available under prescription, it may be hard to tell when someone is abusing the substance or has formed an addiction to it. Some indicators that a person may be struggling with Flexeril addiction include:

  • Taking Flexeril after it’s no longer needed or longer than prescribed

  • Needing more and more of the drug to elicit the same effects

  • Spending the majority of the day thinking about Flexeril: how to get more, the effects it produces, and when to use it

  • Constantly using Flexeril and being unable to stop

  • Faking symptoms to get Flexeril prescriptions

  • Sudden changes in physical appearance, hygiene, and behavior

Finding treatment for Flexeril addiction

If taken in the recommended dosage, Flexeril can be an effective relief for muscle pain and spasm. However, any drug when abused can lead to dependence and the culmination of negative side effects can lead to addiction. If you or anyone you know is suffering from substance abuse then contact a treatment provider today to find out what options are available.

options for Flexeril treatment include:

Flexeril FAQs

These are some of the most commonly asked questions about cyclobenzaprine and Flexeril:

Is Flexeril a controlled substance?

The Controlled Substance Act regulates how drugs are classified and their legal status. Read our guide to see how Flexeril is regulated under the CSA.

How much Flexeril should I take?

Like most prescription medications, different strengths are prescribed depending on the severity of the condition being treated. The same is true of cyclobenzaprine and you can find out more about Flexeril doses and treatment here.

How long does Flexeril stay in your system?

All drugs stay in the human body for a certain amount of time before they are absorbed or removed. This time period varies from substance to substance and can be affected by many different factors. Click here to learn more about how long Flexeril stays in your system. 

Can you take cyclobenzaprine and ibuprofen together?

It is not recommended to take ibuprofen and cyclobenzaprine together as it can lead health complications. Cyclobenzaprine and Flexeril can also have side effects when combined with other drugs.