Iohexol (Injection, Oral rectal)


In order to diagnose patients accurately, various medical tests and procedures are used. As well as carrying out x-rays and MRI scans, physicians may perform CT scans and angiographies so that they are able to capture images inside the patient's body. When CT scans and angiographies are carried out, a contrasting agent may be used to increase the accuracy of these tests.

When Iohexol is administered to the patient, it may adhere to various tissues or cells and enable physicians to diagnose the patient's condition with greater accuracy. As Iohexol can be administered in so many different ways, it can be used to diagnose conditions affecting numerous parts of the body.

When delivered via intravenous injection, for example, Iohexol can be used to help diagnose health problems affecting the back, heart, brain, blood vessels, head and other parts of the body. Similarly, Iohexol delivered via an intrathecal injection enables the medication to be administered into the spinal column or subarachnoid space so that back or spinal problems can be identified. Alternatively, Iohexol can be taken orally or administered rectally in order to diagnose health problems affecting the intestines, stomach, pancreas and/or the joints.

Although Iohexol can cause some patients to experience side-effects, the benefits of using a contrast agent during diagnostic procedures normally outweighs the risk of experiencing subsequent side-effects. With increased accuracy during the diagnostic process, physicians are often able to make quicker diagnoses with the help of Iohexol and treatment can, therefore, be commenced sooner.

Conditions Treated

  • Used during diagnostic procedures, such as CT scans and/or angiographies

Type Of Medicine

  • Iodinated contrast agent

Side Effects

When patients are given any type of medication, they may experience certain side effects. The side effects associated with Iohexol depend on the way the medication is administered. If patients are given Iohexol orally or rectally, for example, they may experience the following side effects:

  • Stomach and/or pain
  • Full and/or bloated feeling
  • Excess gas or air in the stomach or intestines
  • Diarrhea
  • Passing gas
  • Nausea
  • Vomiting
  • Rash on the skin
  • Itching, welts or hives
  • Redness of the skin
  • Unusual drowsiness or sleepiness

However, if Iohexol is administered as an intravascular injection, patients may notice the following side effects:

  • Unpleasant, unusual or bad (after) taste
  • Slurred speech
  • Change in taste
  • Unusual drowsiness or sleepiness
  • Headache
  • Sour or acid stomach
  • Shakiness
  • Anxiety
  • Runny nose
  • Belching
  • Redness of the skin
  • Chills
  • Nightmares
  • Cold sweats
  • Indigestion
  • Coma
  • Pale, cool skin
  • Increased hunger
  • Cough
  • Itching
  • Depression
  • Welts or hives
  • Diarrhea
  • Rash on the skin
  • Dry mouth
  • Sneezing
  • Heartburn
  • Stomach pain, upset or discomfort
  • Uncontrolled eye movements
  • Stuffy nose
  • Vomiting

Similarly, if Iohexol is delivered via intrathecal injection, the following side-effects may occur:

  • Nausea
  • Change in color vision
  • Pain in the back, nerve or neck
  • Vomiting
  • Continuing buzzing or ringing or other unexplained noise in the ears
  • Hearing loss
  • Difficulty seeing at night
  • Increased sensitivity of the eyes to the sun or light
  • Drowsiness
  • Sensation of spinning
  • Loss of appetite

In all cases, the above side-effects may not require medical treatment. If they are fairly mild and are not bothersome to the patient, medical attention may not be needed. In general, the above side effects are likely to diminish after the medication has been administered and the diagnostic procedure has carried out. However, if the above side-effects are persistent, severe or prolonged, patients should always obtain medical help.

In addition to this, patients should obtain immediate medical help if they experience the following side effects after being given Iohexol:

If Iohexol has been taken orally or rectally:

  • Blurred vision
  • Unusual weakness or tiredness
  • Swelling or pain
  • Confusion
  • Sweating
  • Muscle weakness
  • Fast or slow heartbeat
  • Dizziness
  • Nervousness
  • Lightheadedness, faintness or dizziness when getting up suddenly from a sitting or lying position
  • Pounding in the ears
  • Headache

If Iohexol has been administered via intravascular injection:

  • Jaw, back or arm pain
  • Difficulty breathing
  • Discomfort or pain in the chest
  • Dizziness
  • Tightness or heaviness in the chest
  • Fainting
  • Dilated neck veins
  • Irregular, slow or fast heartbeat
  • Lightheadedness or dizziness
  • Nausea
  • Confusion
  • Shortness of breath
  • Blurred vision
  • Sweating
  • Extreme fatigue
  • Lightheadedness, faintness or dizziness when getting up suddenly from a sitting or lying position
  • Swelling in the throat
  • Irregular, pounding or fast pulse or heartbeat
  • Sensation of spinning
  • Feeling cold
  • Seizures
  • Feeling of constant movement of surroundings or self
  • Unusual weakness or tiredness
  • Fever
  • Unusual bruising or bleeding
  • Irregular breathing
  • Swelling of the fingers, lower legs, feet or face
  • Pale skin
  • Troubled breathing with exertion
  • Weight gain

If Iohexol has been delivered via intrathecal injection:

  • Blurred vision
  • Seizures
  • Crawling, burning, itching, prickling, numbness, tingling or "pins and needles" feelings
  • Fast or slow heartbeat
  • Confusion
  • Lightheadedness or dizziness
  • Sweating
  • Faintness, lightheadedness or dizziness when getting up suddenly from a sitting or lying position
  • Unusual weakness or tiredness
  • Nervousness
  • Feeling of constant movement of surroundings or self
  • Pounding in the ears
  • Headache

Patients should also obtain medical attention if they experience any other side-effects after being treated with Iohexol, regardless of how the medication was administered.


When a patient is prescribed Iohexol, their dose of medication will depend on the type of procedure they're having, the strength of the solution used and the way in which the contrast agent in administered. If patients are due to undergo a thoracic myelography, for example, 6-12.5 milliliters of Iohexol may be used via an intrathecal injection, at a strength of 240mgl/mL. Alternatively, if patients are undergoing body scanning with the use of a CT scan, 50-200 milliliters of Iohexol may be used, via intravenous injection, at a strength of 300mgl/mL.

Due to the vast array of diagnostic procedures which are carried out using Iohexol as a contrast agent, the patient's dose will be determined prior to the test. As well as Iohexol being administered prior to the procedure, patients may be given additional Iohexol during the diagnostic test, if it is necessary.

In addition to this, patients may be given steroids or antihistamines prior to the procedure as this can help to prevent the patient from experiencing an allergic reaction to the Iohexol solution. Patients may also be advised to drink a certain amount of fluids as this can help the Iohexol solution to pass through the body more quickly and may reduce the risk of kidney damage occurring.

As Iohexol is usually administered in a clinical setting, patients will not usually need to calculate their own dose of this medication. However, if Iohexol is prescribed in oral form and patients are advised to take the medication prior to testing being carried out, their physician will provide them with specific dosage instructions.

Potential Drug Interactions:

As Iohexol can interact with certain other substances, patients may not be given this contrasting agent if they are taking particular medications. Using Iohexol alongside the following medicine is not recommended, for example:

  • Metformin

Similarly, patients are not usually advised to use the following medicine if they are being treated with Iohexol:

  • Amiodarone

If it is necessary and safe to do so, patients may be advised to stop using existing medications hours or days before Iohexol is to be administered. However, patients should not stop taking existing medication unless they are advised to so by a healthcare professional.

As prescription medicines can sometimes interact with other substances, patients should tell their physician if they are using any over-the-counter medications, supplements or vitamins before Iohexol is administered. Similarly, patients should obtain medical advice before taking vitamins, supplements or over-the-counter medicines once Iohexol has been administered.


If patients have specific health problems, it may not be suitable for Iohexol to be used as their contrasting agent during diagnostic tests. Patients should, therefore, discuss their medical history with their physician prior to Iohexol being prescribed. The following conditions may be particularly relevant:

  • Blood vessel or heart disease
  • Alcohol abuse
  • Epilepsy or seizures
  • Multiple sclerosis
  • Asthma
  • Allergy to iodine
  • Anuria (Inability to pass urine)
  • Allergy to certain foods
  • Kidney disease
  • Overactive thyroid (Hyperthyroidism)
  • Allergic rhinitis (Hay fever)
  • Previous allergic reaction to a contrast agent
  • Hypersensitivities or allergies
  • Dehydration
  • Congestive heart failure
  • Liver disease
  • Diabetes
  • Pheochromocytoma
  • Blood clotting problems
  • Sickle cell anemia
  • Diabetic nephropathy
  • Multiple myeloma
  • Homocystinuria
  • High levels of paraprotein in the blood (Paraproteinemia)
  • Infection
  • High blood pressure (Hypertension)

If used during angiographic procedures, Iohexol can increase the risk of strokes, heart attacks and/blood clotting problems. Patients should tell their doctor immediately if they experience any of the following symptoms:

  • Trouble breathing
  • Chest pain which may spread to the patient's jaw, arms, neck or back
  • Unusual sweating
  • Faintness
  • Nausea
  • Weakness or numbness in a leg or arm, or on one side of the body
  • Coughing up blood
  • Problems with speech, walking or vision
  • Severe or sudden headache

Some patients may experience serious kidney problems after being treated with Iohexol. Patients should obtain immediate medical assistance if they experience the following symptoms:

  • Confusion
  • Agitation
  • Decreased urine output
  • Muscle twitching
  • Rapid weight gain
  • Dizziness
  • Swelling of the ankles, hands or face
  • Headache

When Iohexol is used as a contrast agent, patients may be exposed to radiation. If patients are concerned about the risk this poses, they should discuss their concerns with their physician prior to the medication being administered.

Iohexol can affect the results of certain medical tests. Patients should inform any healthcare professional they liaise with that they have been treated with Iohexol. This includes dentists if the patient is due to undergo any dental work.

If Iohexol is prescribed to pregnant patients, it may be possible for small amounts of the contrast agent to cross the placenta and reach the fetus. However, it is not known what level of risk this poses. Patients should inform their physician if they are pregnant and discuss the possible risks associated with the proposed diagnostic test.

Although Iohexol can be transferred to an infant via breastfeeding, it is not thought it poses a significant risk to the child. However, patients should obtain medical advice before breastfeeding if they have been treated with Iohexol. If patients are currently breastfeeding, they may be advised to interrupt nursing and/or express breastmilk in advance.

Before being treated with Iohexol, patients should tell their physician if they have any existing allergies or if they have ever displayed an allergic reaction to any medicines, dyes or contrasting agents. In some cases, Iohexol may cause patients to suffer a serious allergic reaction, including anaphylaxis. If so, the patient will require emergency medical treatment and should notify the nearest healthcare practitioner if they experience the following symptoms:

  • Shortness of breath
  • Rash on the skin
  • Itching
  • Swelling of the tongue, face or throat
  • Tightness in the chest
  • Wheezing
  • Difficulty breathing
  • Difficulty swallowing
  • Sweating
  • Hoarseness
  • Hives


In order to ensure Iohexol is appropriate for use, it should be stored in accordance with the manufacturer's guidelines. When Iohexol is manufactured as an injectable solution, it is usually supplied in single-use vials and these should typically be kept at a controlled room temperature, between 20?-25?C (68?-77?F). Generally, the vials should be protected from light.

Similarly, if Iohexol is to be administered orally, it may be supplied as a powder. When the medication is due to be used, a healthcare practitioner will prepare the powder with liquid so that it forms a drinkable solution. In most cases, Iohexol powder can be kept at room temperature but should not be exposed to direct light or sunlight.

As Iohexol is usually administered in a clinical setting, such as a hospital or treatment center, patients will not usually be required to store this medication at home. However, if patients are prescribed an oral form of Iohexol to be taken at home, they should adhere to the manufacturer's instructions when storing it. In addition to this, patients should ensure that the medication is kept somewhere safe and that children and/or pets cannot gain access to it.


In order to diagnose certain medical conditions and problems, physicians must be able to look inside the patient's body. Medical and technological advancements mean that non-invasive imaging tests can often be used to enable doctors to examine the patient internally. However, these images must be clear and visible in order for them to be useful in the diagnostic process.

By administering a contrast agent, such as Iohexol, prior to or during a diagnostic procedure, doctors can obtain clearer and more accurate images. As a result, they are able to make a more accurate diagnosis and recommend the most appropriate treatment for the patient, if treatment is required.

Using Iohexol, or a similar contrast agent, can prevent patients from having to undergo more invasive diagnostic procedures and can lead to reduced diagnostic times. As Iohexol can be used during the course of various procedures and can be administered to both adult and pediatric patients, it is a commonly-used contrasting agent and is well-tolerated by the majority of patients.