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Understanding Cyclobenzaprine Side Effects Like Weight Gain—A Complete Guide

Understanding Cyclobenzaprine Side Effects Like Weight Gain—A Complete Guide

In today’s fast-paced world, not being able to achieve a restful night’s sleep has become a common challenge. Due to demanding daily routines, heightened stress, constant exposure to screens, and the ever-present pressure to meet deadlines, you may find yourself lying in your bed at night, unable to fall asleep.

When you’re faced with persistent sleep issues, seeking guidance from a medical professional becomes crucial for your well-being. They can provide personalized insights into improving your sleep hygiene and may recommend sleep medications, such as cyclobenzaprine, to boost the quality of your sleep. Cyclobenzaprine is renowned for its effectiveness in promoting and maintaining uninterrupted sleep throughout the night.

Like many other drugs, cyclobenzaprine comes with potential unwanted reactions. This article will discuss cyclobenzaprine side effects such as weight gain and loss, as well as other ones, to help you make informed decisions about your health and well-being.

What Is Cyclobenzaprine?

Sold under the brand name Flexeril, cyclobenzaprine is a muscle relaxant used to treat muscle problems. 

The drug is prescribed to individuals with:

  • Muscle spasms associated with acute musculoskeletal conditions—This includes muscle spasms caused by muscle strains, sprains, and other injuries
  • Fibromyalgia—This is a chronic pain disorder that causes widespread muscle pain, fatigue, and other symptoms
  • Temporomandibular joint (TMJ) disorder—TMJ disorder is a condition that affects the joints that connect the lower jaw to the skull. It can cause pain, clicking, and popping in the jaw joints
  • Insomnia—Your doctor may prescribe cyclobenzaprine for insomnia in certain situations due to its sedative effects, helping you initiate and maintain sleep
  • Other musculoskeletal conditions—Cyclobenzaprine may also be prescribed for other musculoskeletal conditions, such as back pain, neck pain, and bursitis

Doctors usually prescribe cyclobenzaprine for short-term use (up to 2–3 weeks) in conjunction with rest and physical therapy. Keep in mind that cyclobenzaprine isn’t a cure for muscle spasms, insomnia, or other musculoskeletal conditions—it’s a medication that helps relieve the symptoms.

Here’s some basic information about cyclobenzaprine:



Drug class

Skeletal muscle relaxant

FDA classification

Not a controlled drug




5 mg, 10 mg, 15 mg, and 30 mg

Dosage forms available

Oral capsule/tablet

Suitable for children


Suitable for pregnant women

Category B (no proven risk in pregnancy)

Side effects


How Cyclobenzaprine Works—A Quick Overview

Cyclobenzaprine works by blocking the reuptake of serotonin in the brain and spinal cord. Serotonin is a neurotransmitter that plays a role in muscle control, pain perception, and mood regulation. By blocking the reuptake of serotonin, cyclobenzaprine increases the amount of serotonin available in the central nervous system. This increased serotonin level helps relax muscles, reduce inflammation, and relieve pain.

Since it promotes relaxation, cyclobenzaprine also helps you fall asleep and improve your sleep quality.

Source: SHVETS production

Does Cyclobenzaprine Cause Weight Gain or Weight Loss?

If you’ve recently started using cyclobenzaprine, you might be wondering—will cyclobenzaprine cause weight gain? Weight changes, including both weight gain and weight loss, are potential side effects associated with the use of cyclobenzaprine. However, individual responses to the medication can vary, and not everyone may experience significant changes in weight.

Can Cyclobenzaprine Cause Weight Gain?

Weight gain wasn’t reported in clinical studies of cyclobenzaprine, but in rare cases, people have reported gaining weight after starting the medication. It’s not confirmed that cyclobenzaprine is the cause of the weight gain in these cases, but it’s a possibility. Although the exact mechanism by which cyclobenzaprine may cause weight gain isn’t fully understood, there are a few possible explanations:

Side Effect


Increased appetite

In rare cases, increased appetite can be a side effect of cyclobenzaprine, leading to weight. The drug may block the activity of certain chemicals in the brain that control hunger, such as norepinephrine

Fluid retention

Cyclobenzaprine can cause fluid retention, which can lead to temporary weight gain

Reduced physical activity

Cyclobenzaprine can cause drowsiness and dizziness, which can make it difficult to exercise. This can lead to weight gain, especially for those who are already overweight or obese

Does Cyclobenzaprine Cause Water Retention?

Yes, cyclobenzaprine can cause water retention. This is a relatively common side effect of the drug, and it’s thought to be related to the drug’s anticholinergic effects. Anticholinergic drugs block the effects of a neurotransmitter called acetylcholine that’s involved in various bodily functions, including fluid balance. When acetylcholine is blocked, the body may retain more water, which can lead to swelling and weight gain.

Water retention is typically mild and resolves on its own after you discontinue the use of cyclobenzaprine. if you experience severe water retention or other side effects while taking cyclobenzaprine, consult your doctor.

Here are five tips for managing water retention while taking cyclobenzaprine:

  1. Drink plenty of fluids—Staying hydrated can help flush out excess fluids from your body
  2. Avoid processed foods and sugary drinks—Processed foods and sugary drinks often contain high levels of sodium, which can contribute to water retention
  3. Exercise regularly—Exercise can help reduce swelling and improve fluid circulation
  4. Wear loose-fitting clothing—Tight clothing can restrict circulation and worsen swelling
  5. Elevate your legs when sitting or lying down—Elevating your legs can help improve fluid circulation and reduce swelling in your feet and ankles

Can Cyclobenzaprine Cause Diarrhea?

Besides changes in weight, you may be concerned about other possible side effects like diarrhea. Diarrhea isn’t commonly associated with the use of cyclobenzaprine. Still, like any medication, individual responses can vary, and some people may experience gastrointestinal side effects. If you notice persistent or severe diarrhea while taking cyclobenzaprine, it’s important to consult your healthcare provider. They can assess your specific situation and determine whether any adjustments to your treatment plan are necessary.

Cyclobenzaprine—Important Disclaimers

There are a few precautions to keep in mind before you start using cyclobenzaprine. These include:

  • Cyclobenzaprine is a prescription medication, so make sure to tell your doctor about any other medications you’re taking, including over-the-counter medications, herbal supplements, and vitamins
  • You shouldn’t use cyclobenzaprine if you have a history of heart problems, such as arrhythmia or heart failure
  • Don’t use cyclobenzaprine if you have glaucoma, myasthenia gravis, or an overactive thyroid
  • Avoid drinking alcohol or taking other depressants while taking cyclobenzaprine
  • If you’re pregnant or breastfeeding, you should talk to your doctor about the risks and benefits of taking cyclobenzaprine

If you're considering using cyclobenzaprine to resolve sleep problems, it's crucial to first consult a sleep expert to discuss your specific situation, explore potential risks and benefits, and determine the most appropriate course of action for improving your sleep. Finding such experts can be challenging, as only 1% of physicians in the U.S. are trained in sleep medicine. 

Performance medicine platforms like Kick offer a quick solution. Through Kick, you can get efficient and personalized sleep treatment online, bypassing extended waiting periods and complicated procedures.

Kick—Instant Relief From Sleeplessness

Kick is an online clinic specializing in performance medicine, providing you with easy access to sleep specialists. Instead of arranging an in-person doctor visit, you can fill out a brief survey online and connect with one of our sleep experts within a day. After enrolling in Kick's sleep program, which was designed by a Stanford sleep doctor, our sleep expert will:

  1. Evaluate your current health status and medical history
  2. Develop a personalized sleep treatment strategy for you
  3. Prescribe two trial medications to assess their effectiveness
  4. Adjust your treatment based on your feedback for ongoing progress
  5. Offer cognitive-behavioral therapy for insomnia (CBT-I) coaching to support sustainable, healthy sleep habits
  6. Conduct regular check-ins to monitor and optimize your progress

You can try Kick risk-free thanks to our Doctor Guarantee policy. If our sleep doctor decides that Kick’s sleep program isn’t the best fit for your needs, they’ll refer you to your primary healthcare provider, and you won’t incur any charges for the initial consultation.

Celebrate Your Mornings With Kick

Source: Andrea Piacquadio

To discover why Kick’s sleep program earns high praise from patients, as evidenced by its outstanding Trustpilot reviews, follow these four simple steps:

  1. Go to the sign-up page to start your 15-minute sleep visit
  2. Enter the necessary details to help us understand your condition and your medical history
  3. Choose whether you’d like your medication delivered to your doorstep or a local pharmacy for pickup
  4. Share your shipping address and payment information

Ready to transform your sleep and enhance your well-being? Take the first step by joining Kick today and get personalized sleep solution and guidance from experts.

Can Cyclobenzaprine Cause Eye Problems?

Source: cottonbro studio

Yes, cyclobenzaprine can cause temporary eye problems. This side effect is also related to the drug’s anticholinergic effects, as acetylcholine is involved in other bodily functions such as muscle control, vision, and tear production. When acetylcholine is blocked, the pupils may dilate, which can make it difficult to see in low-light conditions. Cyclobenzaprine can also reduce tear production, which can lead to dry eyes.

Other eye problems that may be caused by cyclobenzaprine include:

  • Blurred vision
  • Double vision
  • Eye pain
  • Increased pressure in the eye

Here are some tips for managing eye problems while taking cyclobenzaprine:

  • Use artificial tears to keep your eyes moist
  • Wear sunglasses to protect your eyes from the sun and bright lights
  • Avoid driving or operating machinery if you’re experiencing blurred vision or other eye problems

Other Cyclobenzaprine Side Effects To Consider

Source: Monstera Production

In addition to the side effects related to weight and vision, there are other potential reactions commonly associated with the use of cyclobenzaprine, such as:

  • Drowsiness
  • Dizziness
  • Fatigue
  • Headache
  • Nausea
  • Difficulty concentrating
  • Constipation
  • Unpleasant taste in the mouth
  • Urinary retention
  • Dry mouth
  • Muscle twitching

This isn’t an exhaustive list of all potential cyclobenzaprine side effects. If you notice any side effects that aren’t listed here or you have any concerns about the side effects you’re experiencing, talk to your doctor. Keep in mind that some of the side effects listed here may be more likely to occur for certain groups, such as older adults or people with other medical conditions.

Featured image source: SHVETS production