Amrix (cyclobenzaprine hydrochloride) is a prescription oral capsule that’s used to treat muscle spasms. It’s usually taken once per day for up to 3 weeks.

Amrix is used in adults to treat certain types of muscle spasms. If you need short-term relief from a muscle spasm caused by a musculoskeletal condition such as a muscle strain, your doctor may prescribe Amrix. It’s used along with rest and physical therapy.

The active ingredient in Amrix is cyclobenzaprine hydrochloride. (An active ingredient is what makes a drug work.) Amrix belongs to a group of drugs called muscle relaxants.

This article describes the dosages of Amrix, as well as its strengths and how to take it. To learn more about Amrix, see this in-depth article.

Note: Amrix is not prescribed for muscle spasms related to diseases of the brain and spinal cord, such as cerebral palsy.

The table below highlights the typical dosage of Amrix. The dosage is given in milligrams (mg).

UseTypical dosage
Short-term relief of muscle spasm in adults15 mg once per day for up to 3 weeks

Keep reading for more details about Amrix’s dosage.

What is Amrix’s form?

Amrix is available as an extended-release capsule that you take by mouth. “Extended-release” means the drug is slowly released into your body over a period of time.

What strengths does Amrix come in?

Amrix comes in two strengths: 15 mg and 30 mg.

What are the usual dosages of Amrix?

The information below describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.

Dosage for muscle spasms

The typical Amrix dosage for adults with muscle spasms from musculoskeletal conditions is 15 mg once per day.

But some people may need a dosage of 30 mg once per day to control their spasms. This dosage may be prescribed using two 15-mg capsules or a single 30-mg capsule.

Amrix is usually prescribed in combination with rest and physical therapy.

Is Amrix used long term?

No, Amrix is not used long term. It should only be used for up to 2 or 3 weeks.

The dosage of Amrix you’re prescribed may depend on several factors. These include:

  • the type and severity of the condition you’re using the drug to treat
  • other conditions you may have or other medications you may be taking

Amrix is available as an oral capsule. Here are a few tips for taking Amrix capsules:

  • It’s best to take your Amrix dose at around the same time of day every day. This helps keep a consistent amount of the drug in your body.
  • If you have trouble swallowing capsules, you can:
    • Open the Amrix capsule and sprinkle the contents onto a tablespoonful of applesauce.* Without chewing, swallow the applesauce and Amrix medication. Then rinse your mouth with water to make sure you’ve swallowed any drug particles that may still be in your mouth.
    • See this article for other tips on how to swallow capsules.
  • For information on the expiration, storage, and disposal of Amrix, talk with your doctor or pharmacist.

* Don’t use another food instead of applesauce. The drug manufacturer did not test other foods for this use.

Accessible drug containers and labels

Some pharmacies provide medication labels that:

  • have large print
  • use braille
  • feature a code you can scan with a smartphone to change the text to audio

Your doctor or pharmacist may be able to recommend pharmacies that offer these accessibility features if your current pharmacy doesn’t.

Let your pharmacist know if you have trouble opening medication bottles. They may have tips to help, or they may be able to supply Amrix in an easy-open container.

If you miss a dose of Amrix, take it as soon as you remember. But if it’s almost time for your next dose, skip the missed dose and take your next dose at its usual time. If you’re not sure whether you should take a missed dose, talk with your doctor or pharmacist.

If you need help remembering to take your dose of Amrix on time, try using a medication reminder. This can include setting an alarm or downloading a reminder app on your phone.

Do not take more Amrix than your doctor prescribes, as this can lead to harmful effects.

Effects of overdose

Effects of an overdose of Amrix can include:

What to do in case you take too much Amrix

Call your doctor right away if you think you’ve taken too much Amrix. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

It isn’t known if Amrix may cause withdrawal and dependence. But its chemical structure is similar to other drugs that may cause these problems.

Because of this, Amrix should only be used for 2–3 weeks. When used short term in this way, Amrix is less likely to cause physical dependence. Physical dependence occurs when your body relies on a drug to function as usual. Taking Amrix for longer periods may lead to physical dependence.

If you suddenly stop taking Amrix after taking it long term, you may experience withdrawal symptoms. These are side effects that can occur when you stop taking a drug that your body has become dependent on.

Examples of withdrawal symptoms include:

If you want to learn more about potential withdrawal symptoms after you stop taking Amrix, talk with your doctor.

Below are answers to some commonly asked questions about Amrix’s dosage.

How does the dosage of Amrix compare with the dosage of Flexeril?

Amrix and Flexeril are muscle relaxants that contain the same active ingredient: cyclobenzaprine hydrochloride. And both drugs are recommended for short-term use (3 weeks or less). But the dosages of these drugs differ.

Amrix comes as an extended-release capsule. “Extended-release” means the drug is slowly released into your body over a period of time. Because Amrix is an extended-release drug, it’s typically prescribed to be taken once per day.

Flexeril, on the other hand, is an immediate-release tablet. It’s released into your body right after you take it. Because Flexeril is an immediate-release tablet, it’s typically prescribed to be taken 3 times per day.

The dosages of each drug in milligrams also differ.

For more information on how these drugs compare, talk with your doctor or pharmacist.

Note: Flexeril is no longer available. Its manufacturer discontinued its production. However, the immediate-release generic cyclobenzaprine hydrochloride is available.

Can Amrix be used for fibromyalgia? If so, what’s the dosage?

Amrix is not approved by the FDA (Food and Drug Administration) to treat fibromyalgia. But in some cases, your doctor may prescribe it off-label for this use. (With off-label use, doctors prescribe a drug for a purpose other than what it’s approved for.)

The active ingredient in Amrix is cyclobenzaprine hydrochloride. (An active ingredient is what makes a drug work.) Studies such as this one have shown that cyclobenzaprine may help improve certain symptoms of fibromyalgia, such as pain.

Because Amrix isn’t approved for fibromyalgia, the manufacturer doesn’t provide recommended dosages for this use. If your doctor prescribes Amrix to treat fibromyalgia, they will determine the dosage that’s right for you.

To learn more about your treatment options for fibromyalgia, including Amrix, talk with your doctor.

The sections above describe the usual dosages provided by Amrix’s manufacturer. If your doctor recommends this drug, they’ll prescribe the dosage that’s right for you.

Remember, you should not change your dosage of Amrix without your doctor’s recommendation. Only take Amrix exactly as prescribed. Talk with your doctor if you have questions or concerns about your current dosage.

Here are some examples of questions you may want to ask your doctor:

  • If I need a dose of 30 mg/day to control my muscle spasms, can I take 15 mg twice daily?
  • Does my Amrix dosage need to change based on other drugs I take?
  • Do I need to take Amrix every day?

To learn more about Amrix, see this article: Amrix (cyclobenzaprine hydrochloride).

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.