Orphenadrine
Pronunciation: pronunciation varies by local usage.
- Generic name
- orphenadrine
- Brand names
- Norflex
- Drug class
- Skeletal muscle relaxant
- Form
- Extended-release tablet
- Route
- Oral
- Legal status
- Prescription-only medicine
Availability and supply rules vary by country
Trade names by country: Canada
Australia: · Full directory
What orphenadrine is and how it works
Orphenadrine is a skeletal muscle relaxant used as an adjunct to rest, physical therapy, and other measures for relief of discomfort associated with acute painful musculoskeletal conditions. The exact mechanism is not fully established; it does not directly relax tense skeletal muscles but may work by altering the perception of muscle pain. (1)
It is an oral extended-release tablet taken twice daily. It should be used only as part of a comprehensive treatment plan including rest and physical therapy. It is not recommended for children; safety and effectiveness have not been established in pediatric patients. Patients should avoid operating machinery or driving until they know how the medicine affects them due to possible dizziness or drowsiness. Anticholinergic effects like dry mouth, blurred vision, and urinary retention are common.
Mechanism of action: how orphenadrine works
The exact mechanism of action is not fully established. Orphenadrine citrate does not directly relax tense skeletal muscles; its effect is thought to be related to analgesic properties, possibly by altering the perception of muscle pain. (1)
What orphenadrine is used for
Acute painful musculoskeletal conditions
Orphenadrine is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute painful musculoskeletal conditions such as strains, sprains, and muscle injuries. (1)
Before taking orphenadrine
Do not take / not appropriate for
- Glaucoma is a contraindication for orphenadrine. Tell your prescriber about this so they can determine whether orphenadrine is appropriate. (all indications) (1)
- Pyloric or duodenal obstruction is a contraindication for orphenadrine. Tell your prescriber about this so they can determine whether orphenadrine is appropriate. (all indications) (1)
- Stenosing peptic ulcers is a contraindication for orphenadrine. Tell your prescriber about this so they can determine whether orphenadrine is appropriate. (all indications) (1)
- Prostatic hypertrophy or bladder-neck obstruction is a contraindication for orphenadrine. Tell your prescriber about this so they can determine whether orphenadrine is appropriate. (all indications) (1)
- Cardiospasm (megaesophagus) is a contraindication for orphenadrine. Tell your prescriber about this so they can determine whether orphenadrine is appropriate. (all indications) (1)
- Myasthenia gravis is a contraindication for orphenadrine. Tell your prescriber about this so they can determine whether orphenadrine is appropriate. (all indications) (1)
- prior hypersensitivity to orphenadrine is a contraindication for orphenadrine. Tell your prescriber about this so they can determine whether orphenadrine is appropriate. (all indications) (1)
Tell your clinician about
- Any history of glaucoma, stomach or bowel obstruction, peptic ulcers, prostate enlargement or bladder-neck obstruction, esophagus problems, myasthenia gravis, or allergy to orphenadrine.
- If you have a fast heart rate, heart failure, coronary artery disease, or heart rhythm problems.
- If you are pregnant or planning to become pregnant, since safe use in pregnancy has not been established. Breastfeeding-specific guidance is unresolved in the sources reviewed for this page; discuss with your clinician if you are breastfeeding.
- If you take propoxyphene-containing medicines (concomitant use has caused confusion, anxiety, and tremors).
- If you are elderly, as you may be more sensitive to side effects like confusion.
- Any other medications, supplements, or herbal products you are taking.
How to take orphenadrine
- Take one 100 mg extended-release tablet twice daily, in the morning and evening.
- Use only as part of a comprehensive plan that includes rest and physical therapy as directed by your clinician.
- Do not change the dose or stop taking the medicine without consulting your clinician.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1)
Missed dose
Do not take an extra dose to make up for a missed one; contact your clinician if unsure.
Overdose
If you have concerns about a possible overdose, contact your clinician or a poison control service for guidance. (1)
Side effects
Side effects are often anticholinergic or CNS-related. Elderly patients may be more susceptible to confusion and hallucinations.
Anticholinergic effects
What to notice: Dry mouth, blurred vision, pupil dilation, constipation, nausea, vomiting, urinary hesitancy or retention, weakness, palpitations, fast heart rate (tachycardia).
What to do: Tell your clinician if these are bothersome or severe. Do not abruptly stop treatment without advice. (1)
Central nervous system effects
What to notice: Drowsiness, dizziness, light-headedness, headache, tremor, mental confusion (especially in the elderly), hallucinations, agitation.
What to do: Avoid driving or operating machinery until you know how you react. Contact your clinician if confusion or hallucinations occur. (1)
Severe anticholinergic effects or confusion
What to notice: Extreme dry mouth, inability to urinate, severe constipation, hallucinations, agitation, confusion (especially in elderly).
What to do: Contact your clinician promptly; they will advise on whether treatment should continue. (1)
Hypersensitivity reaction
What to do: Contact your clinician promptly if you suspect a hypersensitivity reaction. (1)
Serious warnings
Hypersensitivity reaction —
Action: If you suspect a hypersensitivity reaction, contact your clinician promptly, or seek urgent medical care if you feel unwell or unsafe. (1)
Dizziness, light-headedness, or syncope — urgent
Symptoms: Light-headedness, dizziness, syncope (fainting).
Action: Contact your clinician promptly if these occur, or seek urgent medical care if symptoms are severe or you feel unsafe. (1)
Heart rhythm problems or fast heart rate — warning
Symptoms: Palpitations, rapid heartbeat.
Action: Contact your clinician promptly; the treating clinician determines whether the medicine is continued, reduced, or stopped. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Propoxyphene-containing medicines | Concomitant use has been associated with confusion, anxiety, and tremors. | If this combination occurs, contact your clinician promptly; they will decide whether dosage reduction or discontinuation of one or both medicines is appropriate. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Safe use in pregnancy has not been established. In women of childbearing potential, it should be used only when the potential benefits outweigh the possible hazards. Pregnancy Category C per the reviewed US label. (1)
Breastfeeding
Discuss with your clinician.
Children and adolescents
Not recommended for use in children; safety and effectiveness have not been established in pediatric patients. (1)
Elderly patients
Elderly patients may be more susceptible to mental confusion, and hallucinations have been reported. (1)
Monitoring
Before starting
- Assess for contraindications including glaucoma, gastrointestinal obstruction, prostatic hypertrophy, myasthenia gravis, and cardiac conditions (tachycardia, cardiac decompensation, coronary insufficiency, arrhythmias).
During treatment
- Monitor for anticholinergic side effects (dry mouth, urinary retention, blurred vision, tachycardia) and CNS effects (dizziness, confusion, hallucinations).
- If prolonged therapy is considered, periodic monitoring of blood, urine, and liver function is recommended (per label).
Storage
Follow the pharmacist's or package instructions.
Professional information
Clinician-facing context only. Use the current local prescribing information.
United States
Indication: Acute painful musculoskeletal conditions
Dose summary: One 100 mg extended-release tablet taken twice daily (morning and evening). Total daily dose 200 mg.
Renal context: The label does not address renal impairment and specifies no renal dose adjustment. Because the adverse effects are mainly anticholinergic, and elderly patients may occasionally experience mental confusion, renal and overall clearance should be judged by the prescriber rather than adjusted from a published table. (1)
Hepatic guidance
The label does not address hepatic impairment and specifies no hepatic dose adjustment.
Frequently asked questions
Can orphenadrine be used in children?
No, it is not recommended for children because safety and effectiveness have not been established in pediatric patients. (1)
What should I do if I miss a dose?
Do not take an extra dose to make up for a missed one; contact your clinician if unsure. (1)
Does orphenadrine cause drowsiness?
Yes, dizziness, drowsiness, and light-headedness are possible. Avoid driving or operating machinery until you know how the medicine affects you. (1)
What is the mechanism of action of orphenadrine?
The exact mechanism of action is not fully established. Orphenadrine citrate does not directly relax tense skeletal muscles; its effect is thought to be related to analgesic properties, possibly by altering the perception of muscle pain. (1)
What is the generic name of Orphenadrine?
The generic name is orphenadrine. It is sold under brand names including Norflex. (1)
What class of drug is orphenadrine?
Orphenadrine is classed as: Skeletal muscle relaxant. (1)
References
- Orphenadrine citrate extended-release tablet — prescribing informationU.S. National Library of Medicine, DailyMed · United States · dated 2026 · accessed 2026-08-05 · source 1
- ORPHENADRINE CITRATE TABLET, EXTENDED RELEASE [REMEDYREPACK INC.] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 2
- Orphenadrine — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 3
- ORPHENADRINE CITRATE — FDA approval record (Drugs@FDA ANDA040284)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
- orphenadrine — RxNorm normalized drug concept (RXCUI 202723)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5
Brand names by country
Single-ingredient orphenadrine names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
Canada
- ORFENACE