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Omnipaque 300 Side Effects

Generic Name: iohexol

Note: This document contains side effect information about iohexol. Some of the dosage forms listed on this page may not apply to the brand name Omnipaque 300.

For the Consumer

Applies to iohexol: solution

Along with its needed effects, iohexol (the active ingredient contained in Omnipaque 300) 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 or nurse immediately if any of the following side effects occur while taking iohexol:

More common—Oral or rectal route
  • Swelling or pain
Less common—Intravascular route
  • Arm, back, or jaw pain
  • chest pain or discomfort
  • chest tightness or heaviness
  • difficulty breathing
  • dizziness
  • fainting
  • fast, slow, or irregular heartbeat
  • nausea
  • shortness of breath
  • sweating
  • swelling in the throat
Less common—Oral or rectal route
  • Blurred vision
  • confusion
  • dizziness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • headache
  • nervousness
  • pounding in the ears
  • slow or fast heartbeat
  • sweating
  • unusual tiredness or weakness
Rare—Intrathecal route
  • Blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • confusion
  • dizziness or lightheadedness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • feeling of constant movement of self or surroundings
  • headache
  • nervousness
  • pounding in the ears
  • seizures
  • slow or fast heartbeat
  • sweating
  • unusual tiredness or weakness
Rare—Intravascular route
  • Blurred vision
  • confusion
  • dilated neck veins
  • dizziness or lightheadedness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • extreme fatigue
  • fast, pounding, or irregular heartbeat or pulse
  • feeling cold
  • feeling of constant movement of self or surroundings
  • fever
  • irregular breathing
  • pale skin
  • seizures
  • sensation of spinning
  • swelling of the face, fingers, feet, or lower legs
  • troubled breathing with exertion
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • weight gain
Rare—Oral or rectal route
  • Muscle weakness

Some side effects of iohexol 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:

More common—Intrathecal route
  • Nausea
  • pain in the neck, back, or nerve
More common—Oral or rectal route
  • Abdominal or stomach pain
  • bloated or full feeling
  • diarrhea
  • excess air or gas in the stomach or intestines
  • nausea
  • passing gas
  • vomiting
Less common—Intrathecal route
  • Vomiting
Less common—Intravascular route
  • Bad, unusual, or unpleasant (after) taste
  • change in taste
  • headache
Less common—Oral or rectal route
  • Hives or welts, itching, or skin rash
  • redness of the skin
  • sleepiness or unusual drowsiness
Rare—Intrathecal route
  • Change in color vision
  • continuing ringing or buzzing or other unexplained noise in the ears
  • difficulty seeing at night
  • drowsiness
  • hearing loss
  • increased sensitivity of the eyes to sunlight
  • loss of appetite
  • sensation of spinning
Rare—Intravascular route
  • Acid or sour stomach
  • anxiety
  • belching
  • chills
  • cold sweats
  • coma
  • cool, pale skin
  • cough
  • depression
  • diarrhea
  • dry mouth
  • heartburn
  • hives or welts, itching, or rash
  • increased hunger
  • indigestion
  • nightmares
  • redness of the skin
  • runny nose
  • shakiness
  • sleepiness or unusual drowsiness
  • slurred speech
  • sneezing
  • stomach discomfort, upset, or pain
  • stuffy nose
  • uncontrolled eye movements
  • vomiting

For Healthcare Professionals

Applies to iohexol: injectable solution


The most frequently reported adverse reactions are headache, mild to moderate pain including backache, neckache and stiffness, nausea, and vomiting. These reactions usually occur 1 to 10 hours after injection, and almost all occur within 24 hours. They are usually mild to moderate in degree, lasting for a few hours, and usually disappearing within 24 hours.[Ref]


Very common (10% or more): Diarrhea (oral/body cavity routes)
Common (1% to 10%): Nausea, vomiting, pancreatitis (endoscopic retrograde cholangiopancreatography), lower abdominal pain (hysterosalpingography)
Uncommon (0.1% to 1%): Abdominal pain, stomach ache
Rare (0.01% to 0.1%): Diarrhea
Very rare (less than 0.01%): Tenderness and/or enlargement of the salivary glands ("iodide mumps"), abdominal discomfort
Frequency not reported: Aggravation of pancreatitis, acute pancreatitis[Ref]

Nervous system

Rarely, headaches may be severe or persist for days. Headache is often accompanied by nausea and vomiting and tends to be more frequent and persistent in patients not optimally hydrated.
Aseptic meningitis syndrome was usually preceded by pronounced headaches, nausea and vomiting. Onset usually occurred about 12 to 18 hours postprocedure. Prominent features were meningismus, fever, sometimes with oculomotor signs and mental confusion. Lumbar puncture revealed a high white cell count, high protein content often with a low glucose level and with absence of organisms. The condition usually started to clear spontaneously about 10 hours after onset, with complete recovery over 2 to 3 days.[Ref]

Very common (10% or more): Headache (may be severe and prolonged)
Common (1% to 10%): Dizziness (2%), neuralgia
Uncommon (0.1% to 1%): Aseptic meningitis syndrome (including chemical meningitis), visual hallucinations, somnolence, hemiparesis, transient ischemic attack, cerebral infarction, syncope
Rare (0.01% to 0.1%): Seizure, neurological changes, drowsiness, transitory peripheral neuropathies (sensory and/or motor or nerve root disturbances, myelitis, persistent leg muscle pain or weakness, 6th nerve palsy, or cauda equina syndrome)
Very rare (less than 0.01%): Dysgeusia (transient metallic taste), disturbance in consciousness, transient contrast-induced encephalopathy (including transient memory loss, coma, stupor, retrograde amnesia), sensory abnormalities (including hypoesthesia), paraesthesia, tremor
Frequency not reported: Syncope vasovagal, motor dysfunction (including speech disorder, aphasia, dysarthria), disorientation, abnormal electroencephalogram, meningism[Ref]


Very common (10% or more): Pain
Common (1% to 10%): Feeling hot
Uncommon (0.1% to 1%): Discomfort, fever, hives
Rare (0.01% to 0.1%): Pyrexia, asthenic conditions (including malaise, fatigue), feeling of heaviness, tinnitus, vertigo
Very rare (less than 0.01%): Shivering (chills)
Frequency not reported: Transient hearing loss[Ref]


Common (1% to 10%): Blood amylase increased
Uncommon (0.1% to 1%): Hypoglycemia in pediatrics (0.3%)
Rare (less than 0.1%): Loss of appetite
Frequency not reported: Iodism[Ref]


Severe pain may often result from undue use of pressure or the injection of large volumes. Joint swelling after injection is less with iohexol (the active ingredient contained in Omnipaque 300) than with high osmolar ionic contrast medium. These types of reactions are generally procedurally dependent and of greater frequency when double-contrast technique is employed.[Ref]

Common (1% to 10%): Back pain
Rare (less than 0.1%): Neck pain, pain in extremity, hypertonia
Frequency not reported: Muscle spasm, arthralgia, arthritis, muscle cramps, fasciculation or myoclonia, spinal convulsion, spasticity, stiff neck[Ref]


Common (1% to 10%): Vision abnormalities (including blurred vision and photomas) (2%)
Uncommon (0.1% to 1%): Nystagmus (less than 0.3%)
Rare (less than 0.1%): Photophobia, ocular muscles weakness
Frequency not reported: Transient cortical blindness[Ref]


Common (1% to 10%): Transient increase in serum creatinine (contrast induced nephropathy may occur)
Rare (less than 0.1%): Impairment of renal function including acute renal failure[Ref]


Uncommon (0.1% to 1%): Angina, chest pain, anemia in pediatrics(0.3%)
Rare (0.01% to 0.1%): Bradycardia, arrhythmia, hypotension, hypertension
Very rare (less than 0.01%): Myocardial infarction, flushing
Frequency not reported: Severe cardiac complications (including cardiac arrest, cardio-respiratory arrest), spasm of coronary arteries, chest pain, shock, arterial spasm, ischemia, thrombophlebitis, thrombosis[Ref]


Uncommon (0.1% to 1%): Urticaria, purpura, abscess, pruritus
Frequency not reported: Severe pustular or exfoliative or bullous dermatitis, Stevens-Johnson syndrome, erythema multiforme, toxic epidermal necrolysis, acute generalized exanthematous pustulosis, rash with eosinophilia and systemic symptoms, psoriasis flare-up[Ref]


Uncommon (0.1% to 1%): Dyspnea, rhinitis, coughing, laryngitis
Rare (0.01% to 0.1%): Cough
Very rare (less than 0.01%): Non-cardiogenic pulmonary edema
Frequency not reported: Severe respiratory symptoms and signs, bronchospasm, laryngospasm, asthma attack[Ref]


Rare (less than 0.1%): Difficulty in micturition[Ref]


The hypersensitivity reactions may appear either immediately after the injection or up to a few days later.
Hypersensitivity reactions may occur irrespectively of the dose and mode of administration, and mild symptoms may represent the first signs of a serious anaphylactoid reaction/shock.[Ref]

Rare (less than 0.1%): Hypersensitivity (including dyspnea, rash, erythema, urticaria, pruritus, skin reaction, vasculitis, angioneurotic edema, laryngeal edema, laryngospasm, bronchospasm or non-cardiogenic pulmonary edema)
Frequency not reported: Anaphylactic/anaphylactoid reaction, anaphylactic/anaphylactoid shock[Ref]


Very rare (less than 0.01%): Sweating
Frequency not reported: Thyrotoxicosis, transient hypothyroidism (premature infants, neonates premature breast fed infant, and in other children)[Ref]


Frequency not reported: Administration site reactions, including extravasation[Ref]


Frequency not reported: Confusion, anxiety[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Omnipaque 180 (iohexol)." Amersham Health, Princeton, NJ.

Some side effects of Omnipaque 300 may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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.