Flexon Side Effects

Generic name: orphenadrine

Medically reviewed by Drugs.com. Last updated on Feb 11, 2024.

Note: This document contains side effect information about orphenadrine. Some dosage forms listed on this page may not apply to the brand name Flexon.

Applies to orphenadrine: oral tablet extended release. Other dosage forms:

• injection solution

Serious side effects of Flexon

Along with its needed effects, orphenadrine (the active ingredient contained in Flexon) 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:

Rare

• 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

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

Other side effects of Flexon

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.

General

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.

Hypersensitivity

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]

Psychiatric

Rare (less than 0.1%): Memory disturbances

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

Ocular

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

Cardiovascular

Frequency not reported: Tachycardia, palpitations^[Ref]

Gastrointestinal

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

Genitourinary

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

Musculoskeletal

Frequency not reported: Weakness^[Ref]

Dermatologic

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

Frequency not reported: Pruritus^[Ref]

Hematologic

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

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.

Medical Disclaimer