The truth about ‘cat eye’ nails: When your polish might interfere with your MRI

But how much of that is science, and how much is just speculation?

Dr Shreyas Cadabam, director and interventional radiologist at Cadabams Diagnostics, tells indianexpress.com, “Cat eye nail polish does contain iron oxide or iron-based magnetic particles that respond to a magnet to create the ‘cat eye’ effect. However, these particles are typically present in minimal quantities and are embedded within the polish matrix, which hardens after application. In most cases, this does not pose a direct safety threat in terms of being ‘pulled’ into the MRI scanner like loose metal objects might be.”

That said, he adds that the MRI machine has a very strong magnetic field, and even trace amounts of metal, if not tightly bound or if present in high concentration, “can theoretically cause image artefacts or minor heating, especially if they are near the area being scanned.”

Could wearing magnetic or metallic-based cosmetics distort MRI imaging or pose a risk to the patient?

Dr Cadabam states, “Yes, certain metallic-based cosmetics, especially those containing iron oxide, mica, or bismuth, can distort MRI images, particularly in high-resolution scans or when the scan area is close to where the product is applied. For example, metallic eye makeup can interfere with brain or orbital MRIs by creating artefacts that resemble abnormalities, making diagnosis difficult.

In terms of risk, the heating of metal particles by radiofrequency waves is a theoretical concern, though rare. “More often, the issue concerns compromised image quality rather than physical danger. Nail polishes are generally less likely to cause interference unless the hands are in or near the scan field, such as during a wrist or hand MRI,” explains the doctor.

If someone has recently worn cat eye nail polish, should they disclose this before undergoing an MRI?

Before an MRI, Dr Cadabam believes it is always a good idea to inform the radiology team about any metallic or magnetic substances on or in the body, including cosmetics, tattoos, and nail polish. “While cat eye nail polish is unlikely to pose a significant safety concern, especially if the scan is not of the hand or wrist, disclosure helps the technologist make an informed decision,” he says. 

In most cases, removal is not required. However, the expert mentions that if the scan targets areas near the hands, or if there are visible metallic particles, “the technician may ask for it to be removed to ensure optimal imaging and avoid any unexpected interference.”