What is a primary contraindication for using an AED?

The primary contraindication for using an AED is patients under 1 year of age because traditional AEDs are designed for the physiology of older children and adults. The electrical shock delivered by an AED might be too strong for infants, who have different heart and body sizes and structures. For this age group, specialized equipment or a pediatric dose AED, which reduces the energy delivered, is recommended if available.

Patients over 70 years of age, those with asthma, or allergies do not represent contraindications for AED use as the device can be appropriately employed in these scenarios. The critical factor remains the age and size of the patient when considering the safe application of an AED.