In rare cases, individuals allergic to thistledown Velvet Ant sting may experience anaphylaxis, which is characterized by difficulty breathing, hives, rapid heart rate, and nausea. It's important to note that the severity of the symptoms can vary depending on the individual's sensitivity and the number of bites or stings received. If you are concerned about a specific bite or sting or if symptoms persist or worsen, it is recommended to consult a healthcare professional for proper evaluation and treatment.