Preventing An Allergic Reaction to Contrast Dye

This information will help prevent an allergic reaction to the contrast dye you will receive during your scan.

About Contrast Dye

Sometimes, contrast dye (or contrast) is used in imaging scans to help your doctors see your organs better. There are different kinds of contrast used. Computed tomography (CT) scans and magnetic resonance imaging (MRI) use different kinds of contrast.

Preventing an Allergic Reaction to Contrast with Medication

In the past you had an allergic reaction to contrast that you got during a scan. You are having another scan that requires the same type of contrast. To prevent an allergic reaction, you will need to take a steroid medication before your scan.

There are different medications that you can take to prevent an allergic reaction. Your doctor will tell you which one you need and give you a prescription for it.

You are scheduled to have a ______________scan on __________ at __________ AM | PM.

Prednisone

If you’re taking prednisone before your scan, you will have to take 3 doses of it. Take the first dose 13 hours before your scan, the second dose 7 hours before your scan, and the third dose 1 hour before your scan. If you have any questions about when to take your medication, ask your nurse.

Write down the time you need to take your medications below.

Take 1 (50 milligram) tablet of prednisone at:

_____ AM| PM (13 hours before your scan) on__________(date)

_____ AM| PM (7 hours before your scan) on__________(date)

_____ AM | PM (1 hour before your scan) on__________(date)

Take 50 milligrams (mg) of diphenhydramine (Benadryl^®) with your last dose of prednisone 1 hour before your scan.

Methylprednisolone

If you’re taking methylprednisolone before your scan, you will have to take 3 doses of it. Take the first dose 12 hours before your scan and the second dose 2 hours before your scan. If you have any questions about when to take your medication, ask your nurse.

Write down the time you need to take your medications below.

Take 1 (32 milligram) tablet of methylprednisolone at:

_____ AM | PM (12 hours before your scan) on__________(date)

_____ AM | PM 3 hours before your scan) on__________(date)

You may also need to take 50 mg of diphenhydramine 1 hour before your scan. Your doctor will tell you if you need to do this.

Other Medications

You may need to take other medications or a different medication instead. If you do, your doctor will write more instructions in the “Notes” section. 

Take: __________ at _____ AM | PM, 1 hour before your scan.

Notes