What is in Norflex? Understanding its Composition and Use

October 6, 2025 •

2 min read

Over 200 different active pharmaceutical ingredients are classified as muscle relaxants, with Norflex being one of them. So, what is in Norflex? This medication contains orphenadrine citrate as its primary active ingredient, which is used to treat muscle pain and spasms.

Quick Summary

Norflex's primary active component is orphenadrine citrate, a centrally-acting skeletal muscle relaxant. The drug also contains various inactive ingredients, which differ between oral tablet and injectable formulations. Its mechanism involves anticholinergic actions and effects on the central nervous system.

Key Points

Active Ingredient: The key active ingredient in Norflex is orphenadrine citrate, which is a centrally acting skeletal muscle relaxant.
Mechanism of Action: Orphenadrine works by influencing the central nervous system and blocking muscarinic acetylcholine receptors, contributing to its muscle-relaxing and pain-relieving effects.
Inactive Ingredients: Norflex tablets contain fillers like lactose and binders like ethylcellulose, while injections contain other inactive ingredients like sodium bisulfite and sodium chloride.
Common Side Effects: Due to its anticholinergic action, common side effects include dry mouth, blurred vision, drowsiness, and constipation.
Important Contraindications: Patients with glaucoma, myasthenia gravis, certain ulcers, or urinary tract blockages should not use Norflex.
Drug Interactions: Norflex can increase the effects of other CNS depressants, including alcohol, and other drugs with anticholinergic properties.
Proper Usage: Norflex is intended for short-term use and should be used in conjunction with rest and physical therapy for musculoskeletal pain and spasms.

Norflex's Core Active Ingredient

The fundamental component of Norflex is orphenadrine citrate, a compound derived from diphenhydramine. It is classified as a centrally acting skeletal muscle relaxant, and while its mechanism isn't fully understood, it affects the central nervous system (CNS).

How Orphenadrine Citrate Works

Orphenadrine's effects on the nervous system are believed to be key to its therapeutic action. Its mechanism includes anticholinergic properties, effects on the CNS, and analgesic properties, contributing to muscle relaxation and pain relief.

The Function of Inactive Ingredients in Norflex

Inactive ingredients, or excipients, in Norflex formulations contribute to the drug's form, stability, and release. These vary by dosage form, such as fillers and binders in tablets or preservatives and solvents in injections.

Common Uses and Precautions for Norflex

Norflex is used alongside rest and physical therapy for short-term relief of acute, painful musculoskeletal conditions like sprains and strains. It is important to note safety considerations, including potential drowsiness and interactions with alcohol. Anticholinergic side effects are possible. Use with caution in patients with heart issues. Long-term use safety is not established.

How Does Norflex Compare to Other Muscle Relaxants?

Selecting a muscle relaxant involves considering individual needs and potential side effects. Here's a comparison of Norflex with other common muscle relaxants:


Feature	Norflex (Orphenadrine)	Robaxin (Methocarbamol)	Flexeril (Cyclobenzaprine)	Skelaxin (Metaxalone)
Mechanism of Action	Centrally acting, anticholinergic properties, and analgesic effects.	Centrally acting, depresses CNS and blocks nerve impulses.	Centrally acting; related to tricyclic antidepressants.	Centrally acting muscle relaxant.
Dosing Schedule	Twice a day (extended-release tablets).	Typically three to four times a day.	Three times a day (immediate-release) or once a day (extended-release).	Three to four times a day.
Sedative Effects	Can cause drowsiness, though potentially less sedating than some.	{Link: droracle.ai https://www.droracle.ai/articles/44986/is-norflex-or-robaxin-more-sedating}.	Can cause significant drowsiness.	Generally considered less sedating, but can still cause sleepiness.
Side Effects	Dry mouth, blurred vision, dizziness, headache, urinary retention.	Dizziness, drowsiness, lightheadedness.	Drowsiness, dry mouth, dizziness.	Drowsiness, dizziness, headache.
Anticholinergic Effects	Mild but can be significant, especially in older adults.	Lower risk of causing anticholinergic effects compared to Norflex.	Can cause anticholinergic side effects.	Does not have significant anticholinergic effects.
Drug Interactions	CNS depressants (alcohol, opioids), other anticholinergics.	CNS depressants (alcohol, sedatives).	CNS depressants (alcohol), certain antidepressants.	CNS depressants (alcohol).

Conclusion: Unpacking the Contents of Norflex

Understanding what is in Norflex is essential for patients. Its active ingredient, orphenadrine citrate, provides relief from muscle pain and spasms through CNS action and anticholinergic effects. Inactive ingredients vary by formulation. Patients should be aware of potential side effects, particularly anticholinergic effects and drowsiness. Healthcare providers consider patient history and interactions when prescribing, and Norflex is most effective as part of a comprehensive plan including rest and physical therapy. [^1]

[^1]: For more detailed prescribing information, refer to the official FDA label: Norflex™ - accessdata.fda.gov

Frequently Asked Questions

The main active ingredient in Norflex is orphenadrine citrate, which is a centrally acting skeletal muscle relaxant used for the treatment of muscle pain and spasms.

Orphenadrine works by acting on the central nervous system, affecting how the body senses pain from muscles. It also has mild anticholinergic properties, which can help reduce muscle stiffness.

Common side effects include dry mouth, blurred vision, dizziness, drowsiness, nausea, constipation, and headache.

No, you should not drink alcohol while taking Norflex. Alcohol can increase the sedative effects of the medication, leading to dangerous side effects or death.

Norflex is a brand name for the medication containing the active ingredient orphenadrine citrate. Orphenadrine is the generic name.

Individuals with certain medical conditions, such as glaucoma, myasthenia gravis, an enlarged prostate, or blockages in the gastrointestinal or urinary tracts, should not take Norflex.

Norflex is used as an adjunctive treatment, along with rest and physical therapy, to relieve pain and discomfort associated with acute, painful musculoskeletal conditions like strains and sprains.

Yes, Norflex is available in both extended-release tablet and injectable forms. The inactive ingredients can vary between these two formulations.