The term “muscle relaxant” includes mostly skeletal muscle relaxants which act on the central nervous system (brain and spinal cord) to treat muscle spasms and relax muscles.1,2 Muscle spasms or cramps are sudden involuntary contractions of a muscle or group of muscles caused by too much strain being put on the muscle.3,4 Skeletal muscle relaxants are prescribed by healthcare providers to reduce pain and soreness associated with sprains, strains, other types of muscle injuries such as low back pain, neck pain or tension headaches. 1,2,3

Antispastic medication are used to treat muscle spasticity, which is different from a muscle spasm. Muscle spasticity is a continuous muscle spasm that causes stiffness, rigidity or tightness that can interfere with movement, walking or talking. It is caused by an injury to parts of the brain or spinal cord responsible for movement in conditions such as cerebral palsy.1 Antispastic medications are not used to treat a muscle spasm.1

If you experience pain or soreness due to a muscle spasm, your healthcare provider may prescribe a skeletal muscle relaxant such as orphenadrine.2,5

How do muscle relaxants work?

Skeletal muscle relaxants are used in addition to rest and physical therapy to help relieve muscle spasms.6,7,8 Acting on the central nervous system, they are thought to work by causing a relaxing effect and by preventing your nerves from sending pain signals to your brain.2,3,6,8,9

Orphenadrine is a muscle relaxant which is prescribed as short-term treatment together with other therapies such as physiotherapy and exercise to treat muscle spasms and pain such as back pain and tension headaches.8 Orphenadrine works centrally in the brain to interrupt the nerve pathways which cause pain and muscle contractions.2,9 It gets to work within 1 hour5 and is effective against a wide range of painful muscle spasms.9

What can muscle relaxants be used for?

Muscle relaxants such as orphenadrine may help to relieve muscle spasms and pain associated with sprains and strains or other muscle injury, low back pain, neck pain, whiplash injuries, or pain across the neck and shoulder region due to poor posture. 3,7,8

The musculoskeletal system is made up of bones, muscles, and soft tissue that connect them (such as ligaments and tendons).10 Injuries or overuse of muscles and soft tissue can result in pain and muscle spasms.6

The tissue of the musculoskeletal system can be damaged in various ways, for example a ligament (the tissue that connects one bone to another) may tear. That is called a sprain. Other soft tissue injuries include tears in muscle fibers (strains) or tendons (the tissue that connects muscle to bone).6

Trauma is the most common cause of soft tissue and other musculoskeletal injuries, but repetitive movement during daily activities, poor posture, overuse of a muscle, or sudden jerking movements may also cause soft-tissue injury.6

Treatment will depend on the type and severity of the injury or discomfort, and may include medication to relieve pain or painful muscle spasms, rest, and ice.3,6

If you have a painful muscle spasm or musculoskeletal injury, speak to your healthcare provider to determine if a muscle relaxant is a suitable treatment option for you.

Muscle relaxant frequently asked questions


Muscle relaxants such as orphenadrine should not be given to a child under the age of 12 years.2 It is also important not to share your medication with anyone else, even if you think that they may have the same condition as you.


A muscle relaxant usually acts on the central nervous system (brain and spinal cord) to treat muscle spasms, relax muscles and to alleviate pain in conditions such as sprains, strains, muscle injuries, low back pain, neck pain, and tension headaches.2,7,8 Muscle relaxants do not have an anti-inflammatory action.2 Examples of muscle relaxants include orphenadrine, cyclobenzaprine and methocarbamol.5
NSAIDs (nonsteroidal anti-inflammatory drugs) such as ibuprofen reduce inflammation and pain in certain conditions, such as back pain, toothache, headache, menstrual cramps, minor injuries, and arthritis. NSAIDs can lead to stomach upset and prolonged bleeding. It is therefore best to consult your healthcare provider before taking an NSAID.11,12,13


No matter which muscle relaxant you take, you may experience some side effects. Some side-effects of orphenadrine, as examples include:2

  • Tiredness, drowsiness
  • Weakness
  • Dizziness
  • Dry mouth
  • Headache
  • Blurry vision

You should avoid operating heavy machinery until you know how the medicine affects you, as muscle relaxants may affect your concentration.2 Speak to your healthcare provider if you are concerned about any side effect you may experience.

DISCLAIMER: This editorial has been brought to you by Radiant Health. Content in this editorial is for general information only and is not intended to provide or replace medical or other professional advice. For more information, speak to your Healthcare Professional. NZ-2023-02-0012. TAPS NP19166.