Health Guide
Drug Guide

Radiopaque Agent- diagnostic (Oral route, rectal route, intravenous route, Intra-arterial route, intraspinal route)

Brand Names:

Dosage Forms:

Uses of This Medicine:

Radiopaque agents are drugs used to help diagnose certain medical problems. They contain iodine, which absorbs x-rays. Depending on how they are given, radiopaque agents build up in a particular area of the body. The resulting high level of iodine allows the x-rays to make a "picture" of the area.

The radiopaque agents are used in the diagnosis of:

Radiopaque agents are taken by mouth or given by enema or injection. X-rays are then used to check if there are any problems with the stomach, intestines, kidneys, or other parts of the body.

Some radiopaque agents, such as iohexol, iopamidol, and metrizamide are given by injection into the spinal canal. X-rays are then used to help diagnose problems or diseases in the head, spinal canal, and nervous system.

The doses of radiopaque agents will be different for different patients and depend on the type of test. The strength of the solution is determined by how much iodine it contains. Different tests will require a different strength and amount of solution depending on the age of the patient, the contrast needed, and the x-ray equipment used.

A catheter or syringe is used to put the solution of the radiopaque agent into the bladder or ureters to help diagnose problems or diseases of the kidneys or other areas of the urinary tract. It may also be placed into the uterus and fallopian tubes to help diagnose problems or disease of those organs. After the test is done, the patient expels most of the solution by urinating (after bladder or ureter studies) or from the vagina (after uterine or fallopian tube studies).

Radiopaque agents are to be used only by or under the direct supervision of a doctor.

Before Using This Medicine:

In deciding to receive a diagnostic test, the risks of taking the test must be weighed against the good it will do. This is a decision you and your doctor will make. For these tests, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Children, especially those with other medical problems, may be especially sensitive to the effects of radiopaque agents. This may increase the chance of side effects.

Older adults

Elderly people are especially sensitive to the effects of radiopaque agents. This may increase the chance of side effects.


Studies have not been done in humans with most of the radiopaque agents. However, iohexol, iopamidol, iothalamate, ioversol, ioxaglate, and metrizamide have not been shown to cause birth defects or other problems in animal studies. Some of the radiopaque agents, such as diatrizoates have, on rare occasions, caused hypothyroidism (underactive thyroid) in the baby when they were taken late in the pregnancy. Also, x-rays of the abdomen are usually not recommended during pregnancy. This is to avoid exposing the fetus to radiation. Be sure you have discussed this with your doctor.


Although some of these radiopaque agents pass into the breast milk, they have not been shown to cause problems in nursing babies. However, it may be necessary for you to stop breast-feeding temporarily after receiving a radiopaque agent. Be sure you have discussed this with your doctor.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of diagnostic tests in this class. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

Your doctor may have special instructions for you in preparation for your test. He or she might prescribe a special diet or use of a laxative, depending on the type of test. If you have not received such instructions or if you do not understand them, check with your doctor in advance.

For some tests your doctor may tell you not to eat for several hours before having the test. This is to prevent any food from coming back up and entering your lungs during the test. You may be allowed to drink small amounts of clear liquids; however, check first with your doctor.

If you are on hemodialysis and treated with a gadolinium-based contrast agent (GBCA), your doctor may perform hemodialysis immediately after you receive the contrast agent .

Precautions While Using This Medicine:

Make sure your doctor knows if you are planning to have any thyroid tests in the near future. Even after several weeks or months the results of the thyroid test may be affected by the iodine in this agent.

Seek immediate medical attention if you experience burning or itching of the skin; reddened or darkened patches; skin swelling, hardening and/or tightening; yellow raised spots on the whites of the eyes; joint stiffness; limited range of motion in the arms and legs; pain that is deep in the hip bone or ribs; or muscle weakness. These may be symptoms of a very serious disease called nephrogenic systemic fibrosis (NSF) .

Side Effects of This Medicine:

Along with its needed effects, radiopaque agents can cause serious side effects such as allergic reactions. These effects may occur almost immediately or a few minutes after the radiopaque agent is given. Although these serious side effects appear only rarely, your health care professional will be prepared to give you immediate medical attention if needed. If you have any questions about this, check with your doctor.

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

With injection into the spinal canal
Hallucinations (seeing hearing, or feeling things that are not there)
paralysis of one side of body or of legs and arms
For patients receiving gadolinium-based contrast agents (GBCAs)
Incidence not known
Burning or itching of the skin
joint stiffness
limited range of motion in the arms, hands, legs, or feet
muscle weakness
pain deep in the hip bone or ribs
reddened or darkened patches on the skin
skin swelling, hardening and/or tightening
yellow raised spots on the whites of the eyes

Some side effects 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:

With oral or rectal use
Less common
Diarrhea or laxative effect
With injection into a vein or an artery
More common
Unusual warmth and flushing of skin
Less common
dizziness or lightheadedness
nausea or vomiting
pain or burning at the place of injection
unusual or metallic taste
unusual thirst
With injection into the spinal canal
More common
headache (mild to moderate)
nausea and vomiting (mild to moderate)
stiffness of neck
Less common or rare
Difficult urination
headache (severe)
increased sensitivity of eyes to light
increased sweating
loss of appetite
ringing or buzzing in ears
unusual tiredness or weakness

Not all of the side effects listed above have been reported for each of these agents, but they have been reported for at least one of them. There are some similarities among these agents, so many of the above side effects may occur with any of them.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 10/12/2016

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