Despite several alerts, delayed hypersensitivity skin reactions occurring with iodized contrast products continue to be declared to the ANSM. The agency therefore specifies the measures to limit the risks of occurrence of this undesirable effect.
Often benign and sometimes severe reactions
A delayed hypersensitivity reaction occurs more than an hour until several days after exposure to an allergen substance. Most often, this reaction results in redness and itching in the skin. Often light, these signs disappear quickly when the medication is stopped in question.
In some cases, these reactions can be more severe, last several weeks, touch other organs than skin and sometimes be fatal. They are then manifested by a drug hypersensitivity syndrome with eosinophilia and systemic symptoms (Dress), an acute generalized exanthematic pustulosis (PEAG), Stevens-Johnson syndrome or Lyell syndrome.
The products concerned
The iodized contrast products involved in the occurrence of these delayed hypersensitivity reactions are in particular: Visipaque (Iodixanol), Omnipaque (Iohexol), Iomeron (Iomeprol), Iopamiron (Iopamidol), Ultravist (Iopromide), Xenetix (Iobitridol).
Cross reactions are possible between all iodized contrast products, mainly between iohexol and iodixanol.
Driving
Patients should be informed of the risk of the occurrence of delayed hypersensitivity reactions and mainly rash which can occur from the administration of the iodized contrast product.
In the event of a non -serious skin reaction, the application of dermocorticoids can be proposed. A severe reaction should be quickly identified. It may require rapid hospitalization.
The ANSM also recommends that in the event of a skin reaction (whatever its severity) or an pruritus, an allergological assessment is carried out relating to the different classes of iodized contrast products and not only on the iodized contrast product administered, in order to confirm the allergic nature of the reaction and to secure subsequent radiological procedures.
It is also important to remind patients that allergy to iodine does not exist. An allergy to fish or crustaceans, as well as certain iodized antiseptics, does not prejudge an allergy to products of iodized contrasts. The mechanisms implemented are independent of each other.
