Table of ContentsView AllTable of ContentsSymptomsRisk FactorsTreatmentPrevention
Table of ContentsView All
View All
Table of Contents
Symptoms
Risk Factors
Treatment
Prevention
Acontrast dyeallergic reaction can occur after a diagnostic imaging test, such as magnetic resonance imaging (MRI) or computed tomography (CT) scan. The contrast dye used with these tests is an iodine-based orgadolinium-based substance that’s given through a vein to help internal organs and structures stand out during scans.Studies show that less than 1% of people who receive contrast dye will have a serious allergic reaction.Most reactions occur within an hour of receiving contrast dye and many occur within the first five minutes, though delayed reactions are possible.Symptoms can be serious, such as skin reactions or trouble breathing.BSIP / UIG / Getty ImagesSymptomsContrast dye can cause the body to release chemicals such ashistamine. This triggers allergic-like symptoms that are not common but have been observed with contrast use.Mild reactionsto contrast dyeoccur in 3% to 15% of people receiving contrast.Most of these reactions include:A feeling of warmth or flushing through the bodyNauseaVomitingItchinessMetallic tastein your mouthA sense that you’re urinating but you aren’tThere may be some discomfort when the IV line is inserted, but you shouldn’t feel pain when the dye is injected.Generally, symptoms of a mild reaction occur for a short period and don’t require treatment. Severe reactions occur in less than 1% of people receiving contrast, but they can be life-threatening.Symptoms of a moderate or severe reaction (referred to asanaphylaxis) that can require urgent medical care include:Severe vomitingHivesDifficulty breathingSwelling in the throat or faceHigh-pitched sound when breathingConvulsionsFast heart rateLoss of consciousnessContrast Dye Types and RiskIodine-based contrast dye is used for scans involving X-rays, such as CT scans. Low- and high- osmolality contrast media (LOCM, HOCM) are used, with LOCM iodine-based dye more common and less likely to cause a reaction.Gadolinium-based contrast is used for MRIs and has an even lower likelihood of a reaction when compared with iodine-based contrast.Risk FactorsCertain factors appear to put some people at higher risk for contrast dye allergy or complications. It is more likely to affect the kidneys with contrast-induced nephropathy (CIN) in people diagnosed with:Heart diseaseChronickidney diseaseDiabetesOlder people are more likely to experience CIN and adverse reactions.So are those who takebeta blockermedications.There also may be a higher risk for people withasthmaand underlying allergies, and those who have had past reactions to contrast dye.The Seafood MythDespite the popular myth, having a seafood allergy does not place you at an increased risk of having a reaction to contrast dye.Shellfish allergy is due to the protein content of these foods, not the iodine content. Most people with other food allergies can safely receive contrast without any special intervention. An allergy to topical iodine cleaners or iodides presents no increased risk.TreatmentThe treatment for contrast dye allergy is based on symptoms, meaning that treatment is given to alleviate the specific effects of the reaction.Treatment may include the following:Injectable epinephrine, which relaxes tubes of the lungs calledbronchi, allowing easier breathingAntihistamines, drugs that block the actions of histamineIV fluidsfor treatment oflow blood pressureand shockPreventionUnfortunately, there is no test available to diagnose a contrast dye allergy in advance. Skin testing and blood testing to look for allergies are often not helpful in the diagnosis.Contrast dye allergies are unpredictable and small test doses do not indicate whether or not a reaction will occur, even in people who may have had similar procedures in the past. There are steps you can take, however, if you’ve had contrast dye reaction before.Your healthcare provider may recommend using a different type of contrast or taking medications before the procedure.These drugs can include:Oral corticosteroids such as prednisoneAntihistamines such as Benadryl (diphenhydramine) or Zyrtec (cetirizine)Keep in mind that a contrast dye allergy can only be diagnosed after symptoms have occurred. Otherwise, it’s only possible to determine that a person is at increased risk of a reaction. Skin tests may help to identify a problem in some cases.SummaryIV contrast dye is a solution that’s put into the bloodstream during medical imaging in order to make internal structures, such as organs and blood vessels, easier to see.Mild reactions to contrast dye are fairly common and don’t require treatment. In rare cases, severe and life-threatening emergencies can occur.If you’re concerned about a potential reaction to contrast dye, talk to your healthcare provider about the risks and benefits of having a test with contrast and whether alternatives are available. If you have a history of reactions to contrast dye, always make your healthcare provider aware of any previous reactions.
Acontrast dyeallergic reaction can occur after a diagnostic imaging test, such as magnetic resonance imaging (MRI) or computed tomography (CT) scan. The contrast dye used with these tests is an iodine-based orgadolinium-based substance that’s given through a vein to help internal organs and structures stand out during scans.
Studies show that less than 1% of people who receive contrast dye will have a serious allergic reaction.Most reactions occur within an hour of receiving contrast dye and many occur within the first five minutes, though delayed reactions are possible.Symptoms can be serious, such as skin reactions or trouble breathing.
BSIP / UIG / Getty Images
Contrast dye can cause the body to release chemicals such ashistamine. This triggers allergic-like symptoms that are not common but have been observed with contrast use.
Mild reactionsto contrast dyeoccur in 3% to 15% of people receiving contrast.Most of these reactions include:
There may be some discomfort when the IV line is inserted, but you shouldn’t feel pain when the dye is injected.
Generally, symptoms of a mild reaction occur for a short period and don’t require treatment. Severe reactions occur in less than 1% of people receiving contrast, but they can be life-threatening.
Symptoms of a moderate or severe reaction (referred to asanaphylaxis) that can require urgent medical care include:
Contrast Dye Types and RiskIodine-based contrast dye is used for scans involving X-rays, such as CT scans. Low- and high- osmolality contrast media (LOCM, HOCM) are used, with LOCM iodine-based dye more common and less likely to cause a reaction.Gadolinium-based contrast is used for MRIs and has an even lower likelihood of a reaction when compared with iodine-based contrast.
Contrast Dye Types and Risk
Iodine-based contrast dye is used for scans involving X-rays, such as CT scans. Low- and high- osmolality contrast media (LOCM, HOCM) are used, with LOCM iodine-based dye more common and less likely to cause a reaction.Gadolinium-based contrast is used for MRIs and has an even lower likelihood of a reaction when compared with iodine-based contrast.
Certain factors appear to put some people at higher risk for contrast dye allergy or complications. It is more likely to affect the kidneys with contrast-induced nephropathy (CIN) in people diagnosed with:
Older people are more likely to experience CIN and adverse reactions.So are those who takebeta blockermedications.There also may be a higher risk for people withasthmaand underlying allergies, and those who have had past reactions to contrast dye.
The Seafood MythDespite the popular myth, having a seafood allergy does not place you at an increased risk of having a reaction to contrast dye.Shellfish allergy is due to the protein content of these foods, not the iodine content. Most people with other food allergies can safely receive contrast without any special intervention. An allergy to topical iodine cleaners or iodides presents no increased risk.
The Seafood Myth
Despite the popular myth, having a seafood allergy does not place you at an increased risk of having a reaction to contrast dye.Shellfish allergy is due to the protein content of these foods, not the iodine content. Most people with other food allergies can safely receive contrast without any special intervention. An allergy to topical iodine cleaners or iodides presents no increased risk.
The treatment for contrast dye allergy is based on symptoms, meaning that treatment is given to alleviate the specific effects of the reaction.
Treatment may include the following:
Unfortunately, there is no test available to diagnose a contrast dye allergy in advance. Skin testing and blood testing to look for allergies are often not helpful in the diagnosis.
Contrast dye allergies are unpredictable and small test doses do not indicate whether or not a reaction will occur, even in people who may have had similar procedures in the past. There are steps you can take, however, if you’ve had contrast dye reaction before.
Your healthcare provider may recommend using a different type of contrast or taking medications before the procedure.These drugs can include:
Keep in mind that a contrast dye allergy can only be diagnosed after symptoms have occurred. Otherwise, it’s only possible to determine that a person is at increased risk of a reaction. Skin tests may help to identify a problem in some cases.
Summary
IV contrast dye is a solution that’s put into the bloodstream during medical imaging in order to make internal structures, such as organs and blood vessels, easier to see.
Mild reactions to contrast dye are fairly common and don’t require treatment. In rare cases, severe and life-threatening emergencies can occur.
If you’re concerned about a potential reaction to contrast dye, talk to your healthcare provider about the risks and benefits of having a test with contrast and whether alternatives are available. If you have a history of reactions to contrast dye, always make your healthcare provider aware of any previous reactions.
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.RadiologyInfo.org.Contrast materials.Cha MJ, Kang DY, Lee W, et al.Hypersensitivity reactions to iodinated contrast media: A multicenter study of 196 081 patients.Radiology. 2019;293(1):117-124. doi:10.1148/radiol.2019190485Torres MJ, Trautmann A, Böhm I, Scherer K, Barbaud A, Bavbek S,et al.Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity.Allergy.2021 May;76(5):1325-1339. doi:10.1111/all.14656Macy EM.Current epidemiology and management of radiocontrast-associated acute- and delayed-onset hypersensitivity: A review of the literature.Perm J.2018;22:17-072. doi:10.7812/TPP/17-072Mohapatra A, Hyun G, Semins MJ.Trends in the usage of contrast allergy prophylaxis for endourologic procedures.Urology. 2019;131:53-56. doi:10.1016/j.urology.2019.05.010Mount Sinai School of Medicine.Radiology: Frequently asked questions.Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.Akkash N, Alshutaihi MS.A case of hypertensive crisis following administration of nonionic low molecular weight contrast in hemorrhagic stroke patient: a case report.Ann Med Surg (Lond). 2024 Sep 5;86(10):6285-6288. doi:10.1097/MS9.0000000000002538National Kidney Foundation.Contrast Dye and the Kidneys.American Academy of Allergy, Asthma & Immunology.Radiocontrast hypersensitivity.American Academy of Allergy, Asthma & Immunology.Shellfish Allergy is not a Shell Game.Yale School of Medicine.Radiology & biomedical imaging: premedication policy.Brockow K.Allergy to Radiocontrast Dye.Immunol Allergy Clin North Am. 2022 May;42(2):391-401. doi:10.1016/j.iac.2021.12.001
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.RadiologyInfo.org.Contrast materials.Cha MJ, Kang DY, Lee W, et al.Hypersensitivity reactions to iodinated contrast media: A multicenter study of 196 081 patients.Radiology. 2019;293(1):117-124. doi:10.1148/radiol.2019190485Torres MJ, Trautmann A, Böhm I, Scherer K, Barbaud A, Bavbek S,et al.Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity.Allergy.2021 May;76(5):1325-1339. doi:10.1111/all.14656Macy EM.Current epidemiology and management of radiocontrast-associated acute- and delayed-onset hypersensitivity: A review of the literature.Perm J.2018;22:17-072. doi:10.7812/TPP/17-072Mohapatra A, Hyun G, Semins MJ.Trends in the usage of contrast allergy prophylaxis for endourologic procedures.Urology. 2019;131:53-56. doi:10.1016/j.urology.2019.05.010Mount Sinai School of Medicine.Radiology: Frequently asked questions.Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.Akkash N, Alshutaihi MS.A case of hypertensive crisis following administration of nonionic low molecular weight contrast in hemorrhagic stroke patient: a case report.Ann Med Surg (Lond). 2024 Sep 5;86(10):6285-6288. doi:10.1097/MS9.0000000000002538National Kidney Foundation.Contrast Dye and the Kidneys.American Academy of Allergy, Asthma & Immunology.Radiocontrast hypersensitivity.American Academy of Allergy, Asthma & Immunology.Shellfish Allergy is not a Shell Game.Yale School of Medicine.Radiology & biomedical imaging: premedication policy.Brockow K.Allergy to Radiocontrast Dye.Immunol Allergy Clin North Am. 2022 May;42(2):391-401. doi:10.1016/j.iac.2021.12.001
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
RadiologyInfo.org.Contrast materials.Cha MJ, Kang DY, Lee W, et al.Hypersensitivity reactions to iodinated contrast media: A multicenter study of 196 081 patients.Radiology. 2019;293(1):117-124. doi:10.1148/radiol.2019190485Torres MJ, Trautmann A, Böhm I, Scherer K, Barbaud A, Bavbek S,et al.Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity.Allergy.2021 May;76(5):1325-1339. doi:10.1111/all.14656Macy EM.Current epidemiology and management of radiocontrast-associated acute- and delayed-onset hypersensitivity: A review of the literature.Perm J.2018;22:17-072. doi:10.7812/TPP/17-072Mohapatra A, Hyun G, Semins MJ.Trends in the usage of contrast allergy prophylaxis for endourologic procedures.Urology. 2019;131:53-56. doi:10.1016/j.urology.2019.05.010Mount Sinai School of Medicine.Radiology: Frequently asked questions.Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.Akkash N, Alshutaihi MS.A case of hypertensive crisis following administration of nonionic low molecular weight contrast in hemorrhagic stroke patient: a case report.Ann Med Surg (Lond). 2024 Sep 5;86(10):6285-6288. doi:10.1097/MS9.0000000000002538National Kidney Foundation.Contrast Dye and the Kidneys.American Academy of Allergy, Asthma & Immunology.Radiocontrast hypersensitivity.American Academy of Allergy, Asthma & Immunology.Shellfish Allergy is not a Shell Game.Yale School of Medicine.Radiology & biomedical imaging: premedication policy.Brockow K.Allergy to Radiocontrast Dye.Immunol Allergy Clin North Am. 2022 May;42(2):391-401. doi:10.1016/j.iac.2021.12.001
RadiologyInfo.org.Contrast materials.
Cha MJ, Kang DY, Lee W, et al.Hypersensitivity reactions to iodinated contrast media: A multicenter study of 196 081 patients.Radiology. 2019;293(1):117-124. doi:10.1148/radiol.2019190485
Torres MJ, Trautmann A, Böhm I, Scherer K, Barbaud A, Bavbek S,et al.Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity.Allergy.2021 May;76(5):1325-1339. doi:10.1111/all.14656
Macy EM.Current epidemiology and management of radiocontrast-associated acute- and delayed-onset hypersensitivity: A review of the literature.Perm J.2018;22:17-072. doi:10.7812/TPP/17-072
Mohapatra A, Hyun G, Semins MJ.Trends in the usage of contrast allergy prophylaxis for endourologic procedures.Urology. 2019;131:53-56. doi:10.1016/j.urology.2019.05.010
Mount Sinai School of Medicine.Radiology: Frequently asked questions.
Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.
Akkash N, Alshutaihi MS.A case of hypertensive crisis following administration of nonionic low molecular weight contrast in hemorrhagic stroke patient: a case report.Ann Med Surg (Lond). 2024 Sep 5;86(10):6285-6288. doi:10.1097/MS9.0000000000002538
National Kidney Foundation.Contrast Dye and the Kidneys.
American Academy of Allergy, Asthma & Immunology.Radiocontrast hypersensitivity.
American Academy of Allergy, Asthma & Immunology.Shellfish Allergy is not a Shell Game.
Yale School of Medicine.Radiology & biomedical imaging: premedication policy.
Brockow K.Allergy to Radiocontrast Dye.Immunol Allergy Clin North Am. 2022 May;42(2):391-401. doi:10.1016/j.iac.2021.12.001
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