When your sister says you spent too much on those shoes, you don’t hesitate to turn elsewhere for another assessment. But when the doctor hands you a diagnosis, a second opinion gets trickier.

If you have a straightforward problem with a well-established treatment, like appendicitis, you probably don’t need a second opinion. But if you’re facing a complicated treatment for chronic back pain, cancer, or some other serious condition, seeking one makes sense. “You want to be sure the diagnosis is correct to make sure the treatment plan is correct,” says C. Martin Harris, M.D., chief information officer at the Cleveland Clinic, a top research hospital in Ohio. A second opinion is also warranted if you’re told that your or a family member’s condition can’t or shouldn’t be treated. “If your doctor tells you that your child has scoliosis but no treatment is needed, it’s reasonable to consider seeing a specialist,” says Bob Sheff, M.D., author of The Medical Mentor (STC Healthy Living, $17, www.amazon.com).

As for informing your doctor, that’s a definite yes. “You’re not going to hurt his feelings,” says Harris, and he can help you sort through your options and find a specialist. Someone at a medical school or a research hospital is likely to be the most knowledgeable, but getting an appointment can be tough. “Have your doctor call for you, because most facilities have a special phone line set up for physicians,” says Harris, and your doctor could get you in faster.

Questions to Ask

When you get a second opinion, there are two key things you should find out: Was your first diagnosis accurate, and what are your treatment options? If there are discrepancies between the two diagnoses, instead of getting a third opinion, ask both doctors to explain them. Since you’re probably going to be hit with a lot of information, bring someone to your appointment who can take notes, or ask your doctor if you can tape-record the conversation so you won’t forget anything.