It seems to be a commonly held belief that people with health care concerns always benefit from having more tests. Whether it’s blood work, an X-ray, a CT scan, an MRI or a stress test, the common refrain I hear is, “Doc, better safe than sorry!”

I get that. I understand the deep human need for reassurance and confidence. When my wife had cancer several years ago, I always wanted to be certain that everything was OK. Few things felt better than a normal CT scan.

And yet, sometimes more tests aren’t beneficial. Not only can they be costly, they waste time. Not only do they waste time, they can lead to unnecessary treatment (which also costs more money). Finally, they can cause actual harm to patients.

For example, unnecessary blood tests requiring needle sticks in children can produce longterm anxiety about doctor visits. CT scans performed “just to be safe” can, over time and repetition, increase the risk of cancer due to radiation. (This is especially worrisome in children.) MRI scans are extremely expensive and may or may not change the course of therapy. Cardiac stress testing can produce false positive results (that is, when a thing looks true but isn’t). That may lead to cardiac catheterization, in which dye is injected into the vessels of the heart via a long IV catheter in the wrist or groin. Anytime a needle is introduced, or dye is used, there is the potential for complications like bleeding, infection or unforeseen allergic reaction.

In fact, many diagnostic procedures have potential complications, and not just in the world of cardiology. In my own practice, I sometimes have to do spinal taps (lumbar punctures) to evaluate headaches. And yet that procedure can itself lead to further headaches. For this reason, I try to perform it only when absolutely necessary.

My point isn’t to make anyone afraid of tests. And I’m certainly not trying to cause readers to distrust their physicians. But it’s useful to remember that medical evaluations should be done only when indicated and recommended by a physician.

We have access to so much medical care in America! This fact, combined with web searches on computers and smartphones, often leads not only to information, but to misinformation and anxiety. And at that point, it often feels like the only answer to a concern is another test.

That may or may not be true. I admit that I have been guided, appropriately, by patients who had symptoms and did their research. But more often than that, I’ve had to say, “I don’t think that will help, and I don’t think there’s a reason to do it.” And I am confident I’m not the only physician to have that conversation.

So have the tests your physician says you really need. But when she says you don’t need any, just be happy.

In medicine, as in so many things, less is often more.