What symptom may indicate a severe reaction to antivenom treatment?

The presence of respiratory distress and hypotension following antivenom treatment may indicate a severe allergic reaction or an anaphylactic response. These symptoms are critical because they suggest that the body's immune system is reacting adversely to the antivenom, potentially leading to life-threatening conditions. Respiratory distress could manifest as difficulty breathing, wheezing, or swelling of the airway, while hypotension indicates a significant drop in blood pressure, which could lead to shock. This urgent medical condition requires immediate attention and intervention to prevent further complications or severe health risks.

In contrast, mild symptoms such as nausea and headache, rash and mild itching, or mild stomach pain may occur during treatment but do not typically signify a serious reaction. These less severe symptoms can often be managed and may not require the same level of urgent care as respiratory distress and hypotension.