CHICAGO – Millions of people get steroid shots in their backs to relieve pain. Now they are probably wondering whether it’s safe.

In 23 states, hundreds, possibly thousands, of back-pain patients are being warned to watch for symptoms of meningitis because of a custom-mixed steroid solution that may have been contaminated with fungus. Five people have died and more than 40 others have fallen ill.

Doctors who do these injections say they are extremely safe when done correctly with sterile drugs. And many doctors stick to medications approved by the Food and Drug Administration instead of relying on generally less-regulated “compounding pharmacies” like the Massachusetts company implicated in the outbreak.