IV dye or intravenous radioactive contrast is a commonly used image-based diagnostic ingredient that helps to increase the prominence of an image in different imaging procedures, like CT scan, angiogram, and pyelogram. Iodine contrast is a type of IV dye that contains iodine and works as an effective contrasting element. In most of the intravenous radiocontrast used these days, iodine is an indispensable part. Various forms of IV dye, or Iodine contrast are regularly used in hospitals and diagnostic centers for radio imaging. As per an estimate, in the USA alone, these IV dyes are used more than 10 million times every year. Some people, who are prone to iodine allergy, or allergy to seafood that contains iodine, may be allergenic to these IV dye or iodine contrast.
Allergy to IV Dye or Iodine Contrast
Allergy to IV dye or iodine contrast occur in 5-8 percent of patients, who are receiving it for diagnostic image testing. Allergic reactions to this element include a mild feeling of warmth throughout the body as well as nausea, and vomiting. In most of the cases, allergic symptoms of IV dye or iodine contrast arise only for a short period of time and disappear without any medical intervention. Some patients who are allergic to IV dye or iodine contrast may have rather moderate reactions, including vomiting, hives, and swelling, which may require immediate medical attention. Though very rarely, death due to anaphylaxis out of the allergenic effect of IV dye is also found in some cases.
Characteristics of Allergy to IV Dye or Iodine Contrast
Allergies to IV dye or iodine contrast are not like the other types of allergies, as it does not create any antibody in the blood that can indicate its allergenic nature. It directly releases histamine and some other compounds in the blood that creates allergic symptoms. Several studies have shown that iodine does not have any role in creating these allergies, but it can instigate and enhance the process.
Risk Factors for Allergy to IV Dye or Iodine Contrast
Not everyone with iodine or seafood allergy is susceptible to allergy due to IV dye or iodine contrast. Even, those, who have an allergy to iodine cleaners that are used on the skin, may not be at risk of getting an allergy from iodine contrast.
Some risk factors related to allergy to IV dye or iodine contrast are:
- People, who have a history of any kind of reaction to iodine contrast, have a chance of encountering such problem in future.
- People having a history of asthma and presently taking medicines for the same, may also face problems related to allergy to IV dye or iodine contrast.
- People with any other kind of allergy are at a higher risk of getting allergic reaction to IV dye or iodine contrast.
- It is also found that females and elderly people are at a higher risk of getting allergy from IV dye or iodine contrast.
- People having histories of heart or kidney diseases are at a higher risk of having allergy from iodine contrast.
Diagnosis of Allergy to IV Dye or Iodine Contrast
There is no specific test to detect allergy to IV dye or iodine contrast. Some experts recommend skin testing and RAST for detecting the problem. However, several studies have proved that these tests can't detect the problem of allergy to IV dye or iodine contrast in every case. So, the skin test or RAST can't be used universally. In most of the cases, the problem of allergy to IV dye or iodine contrast is detected only after the symptoms of allergy are identified.
To reduce the risk of allergy from IV dye or iodine contrast, the radiologist questions the patient or his family members on previous history of the patient, in order to understand –
- Whether he is allergic to iodine or seafood
- Whether he is allergic to any other foods or materials
- Whether any problem had occurred while doing similar types of imaging in past.
If the patient has a history of allergy to IV dye, he needs to be given some doses of corticosteroid after the consultation with the doctor. If the application of corticosteroid is not possible, then doctors and experts consult to follow some other diagnosis method. This includes application of diphenhydramine orally or intravenously, a few minutes before using iodine contrast.
Treatment for Allergy to IV Dye or Iodine Contrast
Once the patient is diagnosed with an iodine contrast allergy, the physician may recommend a corticosteroid oral medicine or a corticosteroid cream such as prednisone. These medicines help in relieving signs of any iodine reaction, such as a rash on the skin and in the mouth. Doctors may also ask to avoid all types of foods that contain iodine, as well as ask the patients to alert the experts regarding this problem while undertaking any image testing in the future. If anaphylactic shock occurs due to iodine contrast, it may require instant medical treatment in the form of a shot of epinephrine or antihistamine.
Important Tips for Patients with Allergy to IV Dye or Iodine Contrast
Allergy to IV dye or iodine contrast is not frequently observed. So, it is the responsibility of the patient or his family members to convey this problem to the visiting doctor. Some other pertinent matters that need to be considered at the same time are:
- Injections containing iodine contrast material is to be avoided, particularly for the patients having a history of allergy to IV dye or iodine contrast.
- Any other allergy, including asthma and allergy to certain types of medications, are to be conveyed to the doctor.
- Corticosteroid medication can be considered even if the patient has no or mild symptoms of allergy previously.
- Radiologists must be aware of allergy to iodine contrast and must have a clear knowledge of the treatment procedure.
IV dye or iodine contrast is a common solution used during CT scan or other types of radio imaging. Iodine is not usually an allergen, but some people may be hypersensitive to it. Although, these cases are not commonly visible, doctors and radiologists treating a patient should consider the history of the patient while using IV dye or iodine contrast for imaging. As there is no specific diagnosis procedure available; hence, experts need to depend on the symptoms and their own experience to protect the patient from the allergenic symptoms due to iodine contrast.