Health Topics

How do muscle relaxants work and what are the options available?

It is safe to assume that many of us have experienced muscle pain at some point

Tahani Dakkak, BSc, MMASc, PharmD
May 30, 2023

It is safe to assume that many of us have experienced muscle pain at some point in our lives as a result of muscle sprains and strains, muscle stiffness or muscle spasm/cramps. Muscle spasm is a sudden involuntary contraction of a muscle group, where it may feel like your muscles are ripping apart. It is caused by many factors such as muscle fatigue, dehydration or electrolyte imbalances. Now you may be wondering how this pain can be relieved. But, don't you worry, I have your back! This blog will shed some light on some of the pharmacological therapies available to relieve muscle pain as well as how they work.

What medications are available to relieve muscle pain and how do they work?

There are many medications available to relieve muscle pain, some require a prescription and others can be conveniently found over-the-counter. This blog will focus on medications found over the counter to treat minor muscle pain, since prescription-only medications are typically reserved for major or more serious muscle injuries. This type of injury shouldn't be self-treated and instead you should seek medical attention.

Our last blog touched on two of the most common painkillers taken to relieve muscle pain, which are Acetaminophen (Tylenol) and Ibuprofen (Advil). The blog also discussed the differences between both medications and how to select the one most appropriate for you. On the other hand, this blog will focus on muscle relaxants, which are commonly used to relieve musculoskeletal pain.

Muscle relaxants are one of the most common medications used to relieve muscle cramps and stiffness. Methocarbamol is a popular over-the-counter muscle relaxant used to relieve pain due to muscle stiffness and cramps. It is sold under the brand name Robaxin among many others. It has been commonly recommended for minor muscle pain because it’s deemed safer than other medications where it has minimal sedating adverse effects such as drowsiness and dizziness in comparison to the other options available to treat muscle pain. It also works relatively quickly and relieves pain within 30 minutes to 2 hours after ingestion. The exact mechanism of how muscle relaxants work is still unclear today, however, it’s believed that they block nerve impulses (pain sensation) sent to your brain. The term “muscle relaxant” can be misleading as it is unclear if muscle relaxants actually relax muscles or work directly on muscles.

Many Robax products contain Methocarbamol, Are they all the same?

No, there are slight differences between Robax products and some may be better for you than others, so let me break it down.


Robaxin - Methocarbamol

Robaxin only contains Methocarbamol. It comes in a 500mg and 750mg strength and it’s believed to block pain sensations.

Robaxacet - Methocarbamol + Acetaminophen (325mg)

Robaxacet contains 400mg of Methocarbamol and 325mg of Acetaminophen, a pain relief medication that provides additional pain relief along with Methocarbamol. It is important to note that this product is not deemed safe for patients with liver or kidney disease. Acetaminophen may cause severe liver damage and therefore patients with liver or kidney disease must consult a Pharmacist or a doctor before using this medication.

Robaxacet Extra Strength - Methocarbamol + Acetaminophen (500mg)

Robaxacet Extra strength contains 400mg of Methocarbamol and 500mg of Acetaminophen. It has a higher strength of Acetaminophen in comparison to Robaxacet. The higher strength of Acetaminophen is beneficial for patients who didn't experience adequate pain relief from the lower dose. As previously mentioned, patients with liver or kidney disease must consult a healthcare professional before using this medication since it may cause serious liver damage.

Robax Platinum - Methocarbamol + Ibuprofen (200 mg)

Robax Platinum has 400mg of Methocarbamol and 200 mg of Ibuprofen. Ibuprofen is known as a Nonsteroidal Anti-Inflammatory Drug (NSAID), which helps to reduce inflammation while also reducing pain. Since it reduces inflammation, this product is recommended for muscle pain in patients with inflamed or swollen muscles. However, this medication is deemed unsafe to use on patients who have peptic ulcer disease, gastrointestinal bleeding, diabetes, kidney disease or if they are on any other NSAID medication. I highly recommend you speak to a pharmacist before using this medication.

Robaxisal Extra Strength - Methocarbamol + Acetylsalicylic Acid (Aspirin)  

Robaxisal Extra Strength has 400mg of Methocarbamol and 500mg of Aspirin. Aspirin is also classified as an NSAID, it can reduce inflammation, pain and fever. However, it’s important to note that If you are currently taking any other NSAID medication such as Ibuprofen (Advil), Naproxen (Aleve) or Voltaren Emulgel, then it's highly recommended not to take Robaxisal Extra strength. When Aspirin is taken with an NSAID, it may cause stomach ulcers and gastrointestinal bleeding. I highly recommend you speak to a pharmacist before using this medication.

As previously discussed, muscle pain comes in many shapes and forms. There are many pharmacological options to treat muscle pain where some can be prescribed by a doctor and others can be conveniently found over the counter. It's important to note that not all muscle pains can be self-treated and some may need immediate medical attention.

Before I end this blog, I’d like to leave you with few indicators to help identify if you need to seek immediate medical attention, please visit your doctor if you experience any of the following:

  1. Muscle pain accompanied with high fever (39 °C and over)  
  2. Severe muscle pain that has not been resolved with painkillers
  3. If the pain persists for more than a week
  4. If you experience a serious loss of movement
  5. If you notice skin discoloration or severe swelling

This information is for educational purposes only and is not intended as a substitute for medical advice from a healthcare professional. Please consult your physician or pharmacist for medical advice about your condition or medications.

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