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Norflex Side Effects

Generic Name: orphenadrine

Note: This page contains side effects data for the generic drug orphenadrine. It is possible that some of the dosage forms included below may not apply to the brand name Norflex.

For the Consumer

Applies to orphenadrine: oral tablet, oral tablet extended release

Other dosage forms:

As well as its needed effects, orphenadrine (the active ingredient contained in Norflex) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking orphenadrine, check with your doctor immediately:

  • Chest pain
  • chills
  • cough
  • fever
  • hallucinations (seeing, hearing, or feeling things that are not there)
  • headache
  • shortness of breath, troubled breathing, tightness in chest, and/or wheezing
  • skin rash, hives, itching, or redness
  • sores, ulcers, or white spots on lips or in mouth
  • swollen and/or painful glands
  • unusual bruising or bleeding
  • unusual tiredness or weakness
Incidence not known:
  • Abdominal or stomach pain
  • diarrhea
  • fainting
  • fast, pounding irregular heartbeat or pulse
  • glaucoma
  • joint or muscle pain
  • nausea
  • numbness or tingling of face, hands, or feet
  • redness and soreness of eyes
  • swelling of feet or lower legs
  • vomiting

If any of the following symptoms of overdose occur while taking orphenadrine, get emergency help immediately:

Symptoms of overdose:
  • Blurred vision
  • confusion, delirium, or hallucinations
  • constipation
  • difficult urination
  • drowsiness
  • dry eyes, mouth, nose, or throat
  • eye pain
  • flushing or redness of face
  • troubled breathing

Minor Side Effects

Some orphenadrine side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Less common or rare:
  • Dizziness or lightheadedness
  • excitement, irritability, nervousness, or restlessness
  • headache
  • muscle weakness
  • unusually large pupils of eyes
Incidence not known:
  • Anxiety
  • deep or fast breathing with dizziness
  • itching skin
  • mental confusion
  • numbness of feet, hands and around mouth
  • trembling or shaking of hands or feet shakiness in legs, arms, hands, or feet

For Healthcare Professionals

Applies to orphenadrine: compounding powder, injectable solution, oral tablet extended release

Nervous system

Nervous system side effects have included headache, light-headedness, dizziness, drowsiness, syncope and tremor. Infrequently, elderly patients have experienced mental confusion.[Ref]


Ocular side effects have included blurred vision, dilatation of pupils, and increased ocular tension.[Ref]


Cardiovascular side effects have included tachycardia and palpitations.[Ref]


Genitourinary side effects have included urinary hesitancy and retention.[Ref]


Gastrointestinal side effects have included dry mouth, nausea, vomiting, and gastric irritation.[Ref]


Musculoskeletal side effects have included weakness.[Ref]


Dermatologic side effects have included pruritus, and rarely, urticaria and other dermatosis.[Ref]


Psychiatric side effects have included hallucinations and agitation.[Ref]


Hematologic side effects have included very rare cases of aplastic anemia, however, no causal relationship has been established.[Ref]


1. "Product Information. Norflex (orphenadrine)." 3M Pharmaceuticals, St. Paul, MN.

It is possible that some side effects of Norflex may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.