Amrix (cyclobenzaprine hydrochloride) is a brand-name drug that’s prescribed to help relieve muscle spasms in adults. Amrix comes as an extended-release oral capsule. It’s typically taken once per day for up to 2–3 weeks.

Specifically, the Food and Drug Administration (FDA) has approved Amrix to help relieve muscle spasms caused by short-term muscle injuries, such as a pulled muscle. It’s prescribed in addition to a treatment plan that includes rest and physical therapy.

Amrix belongs to a drug class called muscle relaxants. Amrix is available in a generic version.

Keep reading for specific information about the dosage of Amrix, including its strengths and how to take the medication. For a comprehensive look at Amrix, see this article.

Note: This article describes typical dosages for Amrix provided by the drug’s manufacturer. When taking Amrix, always follow the dosage prescribed by your doctor.

Below is information about the form, strengths, and dosages of Amrix.

Amrix form

Amrix comes as an ER oral capsule. With ER medications, the drug is slowly released into your body over time.

Amrix strengths

Amrix comes in two strengths: 15 milligrams (mg) and 30 mg.

Typical dosages

The following information describes dosages that are commonly prescribed or recommended in adults. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Dosage for muscle relaxant therapy

Doctors may prescribe Amrix to help relieve muscle spasms caused by short-term muscle injuries, such as muscle strains. It’s prescribed in addition to rest and physical therapy.

If your doctor prescribes Amrix, your starting dose will likely be 15 mg. Typically, you’ll take this dose once per day. If this strength isn’t effective, your doctor may recommend increasing your dosage to 30 mg once per day.

Your doctor may prescribe Amrix for up to 2–3 weeks. This is the maximum treatment length that’s recommended.

For more information about your specific dosage, talk with your doctor.

Long-term treatment

Amrix is taken short term for relaxing muscle spasms. Doctors prescribe Amrix for up to 2–3 weeks to help relieve muscle spasms.

This medication isn’t typically prescribed long term.

Talk with your doctor if you have questions about how long you can expect to take Amrix.

The Amrix dosage your doctor prescribes will depend on several factors. These include:

  • how your body responds to Amrix
  • the severity of the symptoms you’re taking Amrix to help relieve

Be sure to tell your doctor about all medications and supplements you take, as well as any health conditions you have. Sharing this information helps your doctor determine whether Amrix is right for you.

Amrix comes as an ER oral capsule that’s usually swallowed whole. You may take your dose with or without food.

If you have trouble swallowing capsules, you can open the Amrix capsule and sprinkle the granules onto a tablespoon of applesauce. Swallow right away, without chewing the granules. Then, drink a glass of water to make sure you’ve swallowed all of the granules.

It’s important to take Amrix around the same time each day. This helps maintain a steady level of the drug in your body so Amrix can work effectively.

If you have questions about taking this medication, talk with your doctor or pharmacist.


Some pharmacies offer labels with large print, braille, or a code you scan with a smartphone to convert text to speech. If your local pharmacy doesn’t have these options, your doctor or pharmacist might be able to recommend a pharmacy that does.

If you’re having trouble opening medication bottles, ask your pharmacist about putting Amrix in an easy-open container. They also may recommend tools that can make it easier to open bottles.

If you miss a dose of Amrix, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose and take your next scheduled dose. Do not take two doses to make up for the missed one. If you’re not sure whether you should take a missed dose or skip it, talk with your doctor or pharmacist.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or putting a note where you’ll see it, such as on your bathroom mirror or bedside table. You could also download a reminder app on your phone.

It’s important that you don’t take more Amrix than your doctor prescribes. For some medications, taking more than the recommended amount may lead to harmful effects or overdose.

Effects of an overdose

Overdose effects of Amrix can include:

In rare cases, an overdose of Amrix can lead to severe heart problems or a coma. It can even be fatal.

If you take more than the recommended amount of Amrix

Call your doctor right away if you believe you’ve taken too much Amrix. Another option is to call America’s Poison Centers at 800-222-1222 or use its online tool. If you have severe symptoms, immediately call 911 or your local emergency number, or go to the nearest emergency room.

Amrix belongs to a class of drugs called muscle relaxants. Some muscle relaxants can cause dependence. With dependence, your body becomes used to a drug and needs it to function as usual.

However, Amrix shouldn’t cause dependence when it’s taken short term. Amrix is usually prescribed for up to 2–3 weeks to help relieve muscle spasms.

If you take Amrix for longer than your doctor recommends, abruptly stopping it may cause withdrawal symptoms. These symptoms include:

If you have questions about your Amrix treatment, talk with your doctor.

Below are some frequently asked questions about Amrix.

Is the dosage of Amrix similar to the dosage of Flexeril?

No, the dosages of Amrix and Flexeril (cyclobenzaprine) are different. It’s also important to note that the brand-name drug Flexeril is no longer available. However, the medication is available as a generic cyclobenzaprine oral tablet.

While Amrix and cyclobenzaprine oral tablets contain the same active ingredient, they come in different forms. Amrix is an extended-release (ER) medication, while the cyclobenzaprine oral tablet is an immediate-release (IR) medication.

With ER medications, the active ingredient is released slowly into your body over time. This usually means these drugs can be taken less frequently without losing effectiveness. The typical dosage of Amrix is 15 mg or 30 mg taken once per day.

With IR medications, the active ingredient is released into your body right away. Typically, IR drugs require more frequent doses than ER drugs to maintain similar levels in the body. The typical dosage of the cyclobenzaprine oral tablet is 5–10 mg, taken up to three times per day.

Both Amrix and cyclobenzaprine are taken short-term for up to 2–3 weeks. Neither form of the drug is FDA-approved for long-term use.

To learn more about how these drugs compare, talk with your doctor.

How long does it take for Amrix to start working?

Amrix starts to work within a couple of hours after you take a dose. It may take a few days to help relieve your muscle spasm. As the spasm relaxes, you may feel less pain and have a better range of motion.

Keep in mind that Amrix should be taken in addition to rest and physical therapy. For the best results, rest the affected muscles and follow your entire treatment plan. This may include stretches or other exercises as recommended by your doctor or physical therapist.

Talk with your doctor if you have questions about what to expect with Amrix treatment.

The dosages in this article are typical dosages provided by the drug’s manufacturer. If your doctor recommends Amrix for you, they will prescribe the dosage that’s right for you. Always follow the dosage that your doctor prescribes.

As with any drug, never change your dosage of Amrix without your doctor’s recommendation. If you have questions about the dosage of Amrix that’s best for you, talk with your doctor.

Besides learning about dosage, you may want other information about Amrix. These additional articles might be helpful:

  • More about Amrix: For information about other aspects of Amrix, refer to this article.
  • Cost: If you’d like to learn about cyclobenzaprine (the active drug in Amrix) and cost, see this article.
  • Details about muscle spasms: For details about preventing muscle spasms and injuries, see our exercise & fitness hub.

Disclaimer: Medical News Today 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.