What Does Norflex Do?: An Overview of the Muscle Relaxant Orphenadrine

October 6, 2025 •

4 min read

Norflex, known by its generic name orphenadrine, was a brand-name muscle relaxant that works by calming overactive nerves in the central nervous system. Although the brand has been discontinued in the U.S., the generic version is still used to treat muscle pain, stiffness, and spasms. Understanding what does Norflex do is essential for patients prescribed its generic form, which is typically used as an adjunct to rest and physical therapy.

Quick Summary

Orphenadrine (formerly Norflex) is a prescription muscle relaxant that acts on the central nervous system to relieve acute musculoskeletal pain and spasms, often alongside rest and physical therapy.

Key Points

Muscle Relaxant: Norflex, or orphenadrine, is a muscle relaxant used to treat pain and stiffness associated with acute musculoskeletal conditions like strains and sprains.
Central Nervous System Action: It works by affecting the central nervous system, calming overactive nerves and blocking pain sensations from reaching the brain, rather than directly acting on the muscles.
Anticholinergic Properties: The drug has anticholinergic effects, which contribute to its therapeutic action and are also responsible for common side effects like dry mouth and blurred vision.
Adjunct Therapy: Orphenadrine is intended as an addition to other treatments like rest and physical therapy, not as a standalone solution.
Generic Available: While the brand name Norflex is discontinued in the U.S., its generic form, orphenadrine, is still available and prescribed.
Caution Advised: Patients with conditions such as glaucoma, myasthenia gravis, or heart problems should not take orphenadrine due to its specific contraindications.

Understanding the Core Function

Norflex, which is the brand name for the drug orphenadrine, functions as a centrally acting skeletal muscle relaxant. This means that rather than acting directly on the muscles themselves, it affects the nervous system to produce a relaxing effect. For this reason, it is commonly prescribed to help relieve the pain, discomfort, and stiffness associated with various acute musculoskeletal conditions, such as strains, sprains, or other muscle injuries.

The Mechanism Behind the Muscle Relaxation

While its precise mechanism is not fully understood, orphenadrine's effects are primarily attributed to two actions within the central nervous system (CNS):

Blocking Nerve Impulses: Orphenadrine appears to interfere with the transmission of nerve signals from the spinal cord to the muscles. By blocking these cholinergic receptors, it helps reduce the involuntary motor activity that contributes to muscle spasms and stiffness.
Anticholinergic Properties: The drug also possesses anticholinergic properties, meaning it blocks the action of the neurotransmitter acetylcholine. These anticholinergic effects also contribute to its muscle-relaxing and pain-relieving abilities. Some of its common side effects, such as dry mouth and blurred vision, are also a result of this anticholinergic activity.

Primary Medical Uses

Orphenadrine is used as a short-term adjunct therapy to manage musculoskeletal pain and discomfort. Common scenarios where it might be prescribed include:

Muscle Strains and Sprains: Relieving the pain and stiffness that result from overexertion or injury to muscles and ligaments.
Back Pain: Easing spasms and discomfort in the lower back caused by injury.
Tension Headaches: Alleviating muscle-related tension in the head and neck.
As an adjunct to other therapies: Its use is intended to supplement, not replace, other methods like rest and physical therapy.

Important Considerations and Comparisons

Before starting treatment, patients should be aware of potential side effects and contraindications. Orphenadrine also has distinct differences when compared to other popular muscle relaxants.

Common Side Effects of Orphenadrine

Side effects are largely due to the drug's anticholinergic properties and can often be managed by adjusting the dosage.

Common side effects include:

Dry mouth
Drowsiness and dizziness
Nausea
Constipation
Blurred vision
Headache
Rapid or irregular heartbeat (tachycardia)
Urinary retention

Who Should Not Take Norflex (Orphenadrine)?

Due to its anticholinergic properties and effects on the nervous system, orphenadrine is contraindicated in individuals with certain medical conditions. These include:

Glaucoma
Myasthenia gravis
Prostatic hypertrophy or bladder neck obstruction
Pyloric or duodenal obstruction
Cardiospasm (megaesophagus)
Known hypersensitivity to orphenadrine

Furthermore, caution is advised for patients with heart problems like cardiac arrhythmia or those over the age of 65, as they may be more susceptible to adverse effects.

Norflex (Orphenadrine) vs. Other Muscle Relaxants


Feature	Orphenadrine (Norflex)	Cyclobenzaprine (Flexeril)	Methocarbamol (Robaxin)
Mechanism	Appears to block cholinergic receptors in the CNS and has anticholinergic properties.	Works in the brainstem to reduce motor neuron excitability.	Depresses the CNS to relax muscles.
Primary Uses	Acute musculoskeletal pain and spasms.	Short-term management of muscle spasms.	Relief of skeletal muscle spasms.
Dosage	Usually taken twice daily for extended-release tablets.	Often taken 3 times daily for immediate-release, or once daily for extended-release.	Varies by formulation, typically 3 to 4 times a day.
Side Effects	Dry mouth, drowsiness, dizziness, constipation, potential for increased heart rate.	Drowsiness, dry mouth, dizziness, fatigue.	Drowsiness, dizziness, nausea.
Controlled Substance?	No.	No.	No.
Special Considerations	Not recommended for elderly patients or those with heart problems, glaucoma.	Caution with liver problems; higher risk of serotonin interactions.	Generally well-tolerated in elderly populations.

The Role of Norflex in Musculoskeletal Treatment

As a muscle relaxant, orphenadrine is intended to offer short-term relief from acute pain and discomfort. It is not meant for long-term use and should always be part of a broader treatment plan involving rest and other therapies, as recommended by a healthcare provider. Its ability to reduce muscle spasms and alleviate pain can help patients regain mobility more quickly and participate more effectively in physical therapy. The choice of orphenadrine over other muscle relaxants often depends on a patient's medical history, potential for side effects, and response to previous medications.

For more detailed information, consult the MedlinePlus drug information page for orphenadrine.

Conclusion

In summary, Norflex (orphenadrine) is a prescription medication that acts on the central nervous system to relieve acute, painful muscle spasms and stiffness. By blocking certain nerve impulses and possessing anticholinergic effects, it helps relax muscles and alleviate discomfort. While the brand name is no longer sold in the U.S., the generic form, orphenadrine, remains a valuable short-term treatment option when combined with rest and physical therapy. Like all medications, it has a specific set of side effects and contraindications, so it is crucial for patients to follow their healthcare provider's instructions carefully.

Frequently Asked Questions

While the brand name Norflex has been discontinued in the United States, the generic version, orphenadrine, is still available and can be prescribed by a doctor.

The onset of action for orphenadrine is typically within one hour after oral administration. Its effects can last for several hours, with extended-release versions offering prolonged relief.

Common side effects include dry mouth, drowsiness, dizziness, constipation, and blurred vision. Less common but more serious side effects can include a rapid or irregular heartbeat.

No, you should not drive or operate heavy machinery until you know how orphenadrine affects you. It can cause drowsiness, dizziness, and blurred vision, which can impair your ability to think and react.

No, orphenadrine is not classified as a controlled substance in the U.S., unlike some other muscle relaxants such as carisoprodol (Soma).

Orphenadrine is contraindicated in patients with conditions such as glaucoma, myasthenia gravis, certain stomach or intestinal blockages, an enlarged prostate, or heart problems.

No, it is not safe to drink alcohol while taking orphenadrine. Alcohol can increase the sedative effects of the medication, making drowsiness and other side effects more severe and dangerous.