A mammogram is an X-ray of the breast that helps detect breast cancer early. It can find lumps that are too small to be felt during a clinical breast exam.

When should I get a mammogram?

There are 2 types of mammograms: screening mammograms and diagnostic mammograms. Screening mammograms are ones you get as part of a regular checkup if you’ve had no symptoms. They let your doctor see what’s normal for your breasts and if there are any changes since your last mammogram.

Mammogram guidelines vary. Most people with breasts should get screening mammograms every year starting at age 40. You may need get one before you turn 40 if someone in your family had breast cancer at a young age, or if you have cysts in your breasts, which can hide the symptoms of breast cancer.

Diagnostic mammograms focus on potential breast problem areas. Your doctor might recommend a diagnostic mammogram after discovering a lump during a clinical breast exam or after an abnormal screening mammogram.

What should I know before my mammogram appointment?

There are things you can do before your appointment to make your mammogram more comfortable and to get the clearest X-ray:

  • Your breasts may be tender and swollen the week before and during your period, so try to schedule your mammogram after your period, when your breasts are less sensitive.

  • Don’t wear deodorant, perfume, or powder the day of your mammogram. They can make the X-ray less clear.

  • They’ll ask you to undress from the waist up when you get a mammogram, so you may want to wear a top and pants or a skirt instead of a dress.

  • If you have breast implants, mention it when you make your appointment.

  • Let your doctor know if you’re pregnant. Screening mammograms aren’t typically done during pregnancy.

  • If it makes you more comfortable, you can ask to have a mammogram technician who’s the same gender as you when you make your appointment.

Are mammograms accurate?

Mammograms are accurate and effective — but it’s possible to get inaccurate results. Sometimes a spot will show up on the X-ray, but a follow-up test will determine that it’s nothing to worry about. In other cases, a mammogram may not find breast cancer that’s there. While mammograms aren't perfect, they remain an important tool in finding breast cancer.

Are mammograms safe?

Some people worry about exposure to radiation from the X-ray, but the amount of radiation is really small. Most experts agree that the benefit of finding cancer early is a lot more important than the small risk of radiation during a mammogram.