Which severe contrast reaction may lead to death?

Convulsions can lead to severe complications that may result in death, making this the correct answer. When convulsions occur, especially in a medical setting where a patient has received contrast material, they can be indicative of a serious underlying issue, such as an anaphylactic reaction, significant electrolyte imbalance, or other complications related to the contrast medium.

Severe convulsions can lead to prolonged seizures, which may result in status epilepticus — a condition that can cause brain injury or even death if not addressed promptly. Additionally, convulsions can cause secondary complications such as aspiration, respiratory distress, and cardiac arrest, all of which can be life-threatening.

While severe urticaria is concerning and can indicate an allergic reaction, it does not typically lead directly to death. Mild asthma symptoms, though they may pose risks to individuals with pre-existing conditions, are often manageable and not immediately life-threatening in contrast reactions. Similarly, nausea and vomiting, while uncomfortable and sometimes severe, are rarely fatal on their own.