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Nuedexta Side Effects

Generic Name: dextromethorphan / quinidine

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

In Summary

Common side effects of Nuedexta include: diarrhea and dizziness. Other side effects include: peripheral edema and vomiting. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to dextromethorphan / quinidine: oral capsule

As well as its needed effects, dextromethorphan / quinidine may cause unwanted side effects that require medical attention.

Major Side Effects

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

Less common:
  • Bladder pain
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • bloody or cloudy urine
  • chills
  • cough
  • diarrhea
  • difficult, burning, or painful urination
  • fever
  • frequent urge to urinate
  • general feeling of discomfort or illness
  • headache
  • joint pain
  • loss of appetite
  • lower back or side pain
  • muscle aches and pains
  • nausea
  • rapid weight gain
  • runny nose
  • shivering
  • sore throat
  • sweating
  • tingling of the hands or feet
  • trouble sleeping
  • unusual tiredness or weakness
  • unusual weight gain or loss
  • vomiting

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

Symptoms of overdose:
  • Aggressive and violent behavior
  • agitation
  • blurred vision
  • change in color vision
  • change in consciousness
  • chest pain or discomfort
  • confusion
  • confusion as to time, place, or person
  • continuing ringing or buzzing or other unexplained noise in the ears
  • decreased awareness or responsiveness
  • depression
  • difficulty seeing at night
  • dizziness or lightheadedness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • double vision
  • excitement
  • fainting
  • fast, pounding, or irregular heartbeat or pulse
  • feeling of constant movement of self or surroundings
  • hallucinations
  • hearing loss
  • holding false beliefs that cannot be changed by fact
  • inability to move the eyes
  • increased blinking or spasms of the eyelid
  • increased sensitivity of the eyes to sunlight
  • irregular or slow heart rate
  • loss of consciousness
  • overactive reflexes
  • poor coordination
  • restlessness
  • seeing double
  • seizures
  • sensation of spinning
  • severe sleepiness
  • shakiness and unsteady walk
  • shivering
  • shortness of breath
  • sticking out of tongue
  • sweating
  • talking or acting with excitement you cannot control
  • trembling or shaking
  • trouble with breathing, speaking, or swallowing
  • twitching
  • uncontrolled eye movements
  • uncontrolled twisting movements of the neck, trunk, arms, or legs
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unusual excitement, nervousness, or restlessness
  • unusual facial expressions

Minor Side Effects

Some dextromethorphan / quinidine 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:
  • Bloated
  • excess air or gas in the stomach or intestines
  • full feeling
  • lack or loss of strength
  • passing gas

For Healthcare Professionals

Applies to dextromethorphan / quinidine: oral capsule


The most commonly reported adverse reactions (2% or greater incidence and greater than placebo) that led to treatment discontinuation were muscle spasticity, abdominal pain, asthenia, dizziness, muscle spasms, respiratory failure, and fall.[Ref]


Very common (10% or more): Diarrhea (13%)
Common (1% to 10%): Abdominal pain, vomiting, flatulence

Postmarketing reports: Nausea, vomiting, stomach pain[Ref]

Nervous system

Very common (10% or more): Dizziness (10%)

Postmarketing reports: Drowsiness, dizziness, nervousness, restlessness

Postmarketing reports: Convulsions, apprehension, ataxia, acute psychotic reactions (rare)[Ref]


Frequency not reported: QTc prolongation[Ref]


Common (1% to 10%): Muscle spasticity, muscle spasms[Ref]


Common (1% to 10%): Increased gamma-glutamyltransferase[Ref]


Common (1% to 10%): Respiratory failure, cough[Ref]


Common (1% to 10%): Asthenia, fall, peripheral edema

Postmarketing reports: Cinchonism[Ref]

Cinchonism is usually a sign of chronic quinidine toxicity, but it may appear in sensitive patients after a single moderate dose of several hundred milligrams. It is characterized by nausea, vomiting, diarrhea, tinnitus headache, hearing loss, vertigo, blurred vision, diplopia, photophobia, confusion, and delirium.[Ref]


Common (1% to 10%): Influenza[Ref]


Common (1% to 10%): Urinary tract infection[Ref]


Postmarketing reports: Mydriasis, disturbed color perception, night blindness, scotomata, optic neuritis, visual field loss, photosensitivity, keratopathy[Ref]


Postmarketing reports: Skin pigmentation abnormalities[Ref]


Postmarketing reports: Depression[Ref]


1. "Product Information. Nuedexta (dextromethorphan-quinidine)." Avanir Pharmaceuticals, Inc, Aliso Viejo, CA.

It is possible that some side effects of Nuedexta 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.