What is the recommended premedication for contrast media (Contrast-Induced Allergy) allergy?

From the Guidelines

For patients with a history of contrast allergy requiring contrast administration, premedication with a combination of corticosteroids and antihistamines is recommended, as supported by the most recent and highest quality study 1. The standard regimen consists of prednisone 50 mg orally at 13 hours, 7 hours, and 1 hour before contrast administration, plus diphenhydramine 50 mg orally or intravenously 1 hour before the procedure. For urgent situations where the full regimen isn't possible, an accelerated protocol can be used: methylprednisolone 40 mg or hydrocortisone 200 mg intravenously every 4 hours until contrast administration, plus diphenhydramine 50 mg intravenously 1 hour before the procedure. These medications work by suppressing the allergic response - corticosteroids inhibit the production of inflammatory mediators and antihistamines block histamine receptors, preventing the symptoms of an allergic reaction. Despite premedication, patients should be monitored closely as breakthrough reactions can still occur. The severity of the previous reaction should guide the decision to use contrast at all, with consideration of alternative imaging techniques for patients with severe previous reactions. Patients should be informed that premedication reduces but does not eliminate the risk of reaction, as noted in the study 1. It's also important to note that the use of premedication in patients with a history of seafood or shellfish allergy is not beneficial, as stated in the guideline 1. The key to managing contrast allergy is to weigh the benefits and risks of contrast administration and to consider alternative imaging techniques when possible, as suggested by the study 1. In cases where contrast administration is necessary, premedication with corticosteroids and antihistamines can help reduce the risk of an allergic reaction, but it is crucial to closely monitor patients and be prepared for potential breakthrough reactions, as emphasized in the study 1. Ultimately, the decision to use premedication and contrast administration should be made on a case-by-case basis, taking into account the individual patient's medical history and the potential risks and benefits of the procedure, as recommended by the study 1.

From the FDA Drug Label

INDICATIONS AND USAGE: Diphenhydramine hydrochloride in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when diphenhydramine hydrochloride in the oral form is impractical Antihistaminic For amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled, and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated. Diphenhydramine can be used as a premedication for allergic reactions, including those related to contrast allergy. The primary use is for amelioration of allergic reactions.

• Key points:
  • Effective for antihistaminic use
  • Used for uncomplicated allergic conditions of the immediate type
  • Can be used when oral therapy is impossible or contraindicated 2

From the Research

Premedication for Contrast Allergy

• The use of premedication for contrast allergy is a topic of ongoing debate, with some studies suggesting its efficacy in preventing acute allergic-like reactions to iodinated contrast media 3, 4.
• A retrospective study of 322 high-risk patients who were reexposed to low osmolar contrast media (LOCM) after premedication with antihistamines and/or systemic corticosteroids found that 85.4% of patients did not experience any reaction, while 14.6% still experienced a breakthrough reaction 3.
• Another study found that emergent premedication with corticosteroids and antihistamines prior to endovascular therapy in patients with acute ischemic stroke and a history of contrast allergy did not result in any allergic reactions 4.
• The effectiveness of premedication regimens, including steroid premedication and contrast material substitution, has been compared in several studies, with some suggesting that contrast material substitution may be more effective in preventing repeat allergic-like reactions 5.

Types of Premedication

• Corticosteroids are commonly used as premedication for contrast allergy, with studies suggesting that they may be effective in reducing the risk of acute allergic-like reactions 3, 6.
• Antihistamines are also used as premedication, often in combination with corticosteroids 3, 4.
• The use of diphenhydramine and corticosteroids as premedication has been questioned, with some studies suggesting that they may be ineffective and have potential side effects 7.

Patient Risk Factors

• Patients with a history of severe hypersensitivity reactions to contrast media are at higher risk of experiencing a breakthrough reaction despite premedication 3, 5.
• Identifying patients at high risk for an allergy-type reaction to contrast media is essential for preventing or mitigating adverse reactions 6.
• Patients with a history of contrast allergy should be carefully evaluated and managed to minimize the risk of a breakthrough reaction 7.