Preparing for an MRI is mostly about removing metal from your body and knowing what to expect once you’re inside the scanner. The exam itself is painless, but the preparation matters because the machine uses an extremely powerful magnet, and anything metallic on or in your body can cause burns, move unexpectedly, or distort the images your doctor needs. Here’s what to do before your appointment.
What to Wear (and What to Avoid)
The simplest approach is to wear loose-fitting cotton or linen clothing with no metal fasteners, zippers, or decorative hardware. Many facilities will ask you to change into a hospital gown anyway, but wearing the right clothes can speed things up and reduce the chance of a problem being missed during screening.
Standard zippers and rivets on jeans are usually fine, but the bigger concern is clothing you might not suspect. A growing number of athletic and “tech” brands weave invisible silver or metallic microfibers into fabric for odor control or temperature regulation. These fibers can heat up inside the scanner and cause burns. UCLA’s MRI safety guidelines specifically flag brands including Lululemon, Athleta, Columbia Omniheat, Duluth Trading Co., Tommy Copper, and Juzo USA as potentially unsafe. Compression wear and tight-fitting spandex clothing are also discouraged. If you’re unsure about a garment, leave it in the changing room and wear what the facility provides.
Before entering the scan room, you’ll need to remove all metallic personal items: watches, jewelry, hair clips, belts, glasses, hearing aids, and anything in your pockets. Bobby pins and underwire bras are easy to forget. Some facilities provide a locker or bag for your belongings.
Fasting Rules Depend on the Scan
If your MRI focuses on the brain, spine, knee, shoulder, or another joint, you typically don’t need to fast at all. Eat and drink normally.
Abdominal and pelvic MRIs are different. Most facilities ask you to stop eating for four hours before the scan. Pelvic floor imaging sometimes requires only a two-hour fast. In all of these cases, you can still take your regular medications with small sips of water. Your scheduling team should give you specific instructions when they book the appointment, but if they don’t, call and ask. Getting the fasting wrong can mean rescheduling.
Implants and Medical Devices
The MRI’s magnet is strong enough to pull on metal inside your body, so your care team will screen you carefully. You’ll fill out a questionnaire asking about pacemakers, cochlear implants, aneurysm clips, metal heart valves, spinal cord stimulators, joint replacements, surgical pins or screws, and any metal fragments from prior injuries or occupations like welding. Many modern implants are labeled “MRI conditional,” meaning they’re safe under specific conditions, but the technologist needs to verify the exact make and model first.
If you have any implanted device, bring the manufacturer’s card or documentation if you have it. This saves time and avoids delays. Some devices require the MRI team to adjust scanner settings or coordinate with the device manufacturer before proceeding.
If You’re Getting Contrast Dye
Some MRI exams require an injection of a contrast agent (a gadolinium-based liquid) through an IV line to make certain tissues show up more clearly. The injection itself feels like a brief cool sensation in your arm, and the agent passes through your system within hours.
If your kidneys are healthy, no special precautions are needed. The main concern is for people with significantly reduced kidney function. Current guidelines use a threshold of 30 for a blood test called eGFR, which measures how well your kidneys filter waste. Below that number, certain contrast agents aren’t recommended because the kidneys may struggle to clear the dye. If your kidney function falls between 30 and 59, standard contrast agents are considered safe with no extra precautions. Your doctor will check your kidney function beforehand if there’s any reason for concern.
Let your team know about any prior allergic reactions to contrast agents used in previous scans. Mild reactions like nausea or hives are uncommon but possible.
How Long the Scan Takes
Plan for more time than just the scan itself. You’ll need to check in, change clothes, complete the safety screening form, and potentially wait for the room to open up. Arriving 15 to 30 minutes early is standard.
The scan duration depends on what part of the body is being imaged. Brain and spine exams average about 45 minutes. If contrast is added, expect up to 15 extra minutes. Joint scans for knees, ankles, hips, elbows, or wrists run 25 to 45 minutes depending on the anatomy involved. A scan of the full thigh bone, for instance, takes longer than a routine knee. In total, block out about 90 minutes to two hours from arrival to leaving the facility.
Managing Anxiety and Claustrophobia
The MRI bore (the tube you lie in) is typically about 60 centimeters wide, and you’ll be inside it for the entire scan. The machine is also loud, producing rhythmic banging and buzzing sounds as it works. If tight spaces or loud noise make you anxious, there are several things you can do.
First, ask your ordering physician about an anti-anxiety medication beforehand. A single dose of a mild sedative taken an hour or so before your appointment can make the experience far more manageable. If you take sedation, you’ll need someone to drive you home. For more severe claustrophobia, some facilities offer IV sedation, where you’ll be in a relaxed, semi-sleepy state during the scan. This typically requires fasting beforehand and a longer recovery period at the facility.
Even without medication, you can prepare. Most facilities offer earplugs or noise-canceling headphones, and some let you listen to music. Closing your eyes before you enter the bore and keeping them closed throughout helps many people avoid the sensation of being enclosed. Breathing slowly and focusing on exhaling can reduce the urge to move or panic. The technologist can hear you and talk to you through a speaker the entire time, and you’ll have a squeeze ball or button to press if you need to stop.
Tattoos and Permanent Makeup
Most tattoos are perfectly safe in an MRI, but older tattoos and certain permanent cosmetics use pigments containing iron oxide or other metals. These can interact with the magnetic field and cause a mild warming or tingling sensation at the tattoo site. In rare cases, they can also create artifacts on the images, particularly permanent eyeliner or eyebrow tattoos near the eyes, where the distortion can mimic actual eye conditions on the scan.
Let your technologist know about any tattoos or permanent cosmetics before the exam. As a precaution, an ice pack or cold compress can be placed directly on a large tattoo during the scan to prevent any heating. If you feel any warmth or discomfort at a tattoo site during the procedure, alert the technologist immediately using the call button.
Preparing a Child for an MRI
Children face the same metal screening as adults, but the bigger challenge is staying completely still for 25 to 45 minutes or longer. Movement blurs the images and can mean repeating the scan.
For older children, preparation starts with an honest, age-appropriate explanation of what will happen. Describe the loud sounds, the narrow tube, and the importance of holding still. Some hospitals have certified child life specialists who are trained in child development and can walk your child through the process using play, visual aids, or tours of the scanner room beforehand. Ask your imaging facility if this service is available.
Younger children and toddlers who can’t stay still on their own will likely need sedation. If sedation is planned, your doctor will give you specific instructions about when to stop food and drink beforehand. Tell the medical team about all medications your child takes, including vitamins and herbal supplements, any drug allergies, and any family history of problems with anesthesia. Your child may need a little extra recovery time afterward, so keep the rest of the day free.