Skip to main content

Orphenadrine Side Effects

Medically reviewed by Last updated on Jul 17, 2021.

For the Consumer

Applies to orphenadrine: oral tablet extended release

Other dosage forms:

Side effects requiring immediate medical attention

Along with its needed effects, orphenadrine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking orphenadrine:


  • 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

Get emergency help immediately if any of the following symptoms of overdose occur while taking orphenadrine:

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

Side effects not requiring immediate medical attention

Some side effects of orphenadrine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions 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


The more commonly reported adverse reactions are due to the anticholinergic effects of this drug; dry mouth is usually the first adverse effect to appear.


Rare (less than 0.1%): Anaphylaxis (with IM injection)

Frequency not reported: Hypersensitivity reactions

Nervous system

Frequency not reported: Headache, light-headedness, dizziness, drowsiness, syncope, tremor, sedation, convulsions, coordination difficulties[Ref]


Rare (less than 0.1%): Memory disturbances

Frequency not reported: Hallucinations, agitation, euphoria, restlessness, mental confusion (especially elderly)[Ref]


Frequency not reported: Blurred vision, dilatation of pupils, increased ocular tension, accommodation disorders[Ref]


Frequency not reported: Tachycardia, palpitations[Ref]


Frequency not reported: Dry mouth, nausea, vomiting, constipation, gastric irritation[Ref]


Frequency not reported: Urinary hesitancy, urinary retention[Ref]


Frequency not reported: Weakness[Ref]


Rare (less than 0.1%): Urticaria, other dermatoses

Frequency not reported: Pruritus[Ref]


Rare (less than 0.1%): Aplastic anemia[Ref]


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

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.