No cautions. It is safe for the head or heart areas.

Warnings

Never use Big Magic in, near, or around water. Big Magic’s magnetic pulses also prohibit its use under the following circumstances:
• During pregnancy.
• While using a non-MRI-safe IUD.
• People or animals with organ transplants.
• People or animals with pacemakers.
• Hearing aids, medical pumps, or other electrical implants/devices.

Non-magnetic metal rods, screws, and plates are safe for PEMF use. If an implant is safe for an MRI, it is safe to use Big Magic.