CHICAGO -- Millions of people get steroid shots in their backs to relieve pain. Now they are probably wondering if 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 perform 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.

"If I was a patient, I would definitely be concerned," said Dr. Michael Schafer, an orthopedic specialist at Chicago's Northwestern Memorial Hospital.

He said Northwestern gets steroids from federally regulated pharmaceutical companies. And in almost 40 years of experience, he has never had a patient develop an infection from these shots.

He and others say patients should ask their doctors if their medications come from compounding pharmacies, which custom-mix and repackage creams, solutions and other drugs.

Some doctors who rely on such places are already rethinking that approach.

Dr. Michael Drass of Allegheny Pain Management, a clinic in Altoona, Pa., said he has pulled all drugs that came from the New England Compounding Center off his shelves -- as the government has urged physicians to do -- and is re-evaluating whether to rely on compounding pharmacies for the medicines he uses to treat patients.

"I've been doing this for 15 years now, and I've done 50,000 injections over that course of time, and I've never seen or heard anything like this. It's a real eye-opener for us in the medical practitioner community," Drass said.

He said he has relied on the New England pharmacy and others like it because they sometimes have medications he can't get elsewhere, sometimes because of drug shortages.

Cost can also be a factor. Some of these suppliers charge less than big pharmaceutical companies. Some clinics that use compounding pharmacies say they are a good source of preservative-free steroids, which are less likely to cause a nerve-related complication.

There have been no reported cases of the injection-related meningitis in Missouri, and two Cape Girardeau pain clinics also report no connection to the tainted medication.

Dr. Carmen N. Keith, a pain management physician and medical director of Saint Francis Medical Center's Pain Management Center, said in a prepared statement that the hospital does not purchase its injections from the New England Compounding Center, the specialty pharmacy linked to the outbreak.

"Before purchasing pharmaceuticals from suppliers, Saint Francis does due diligence in researching distributors' recall records with the FDA and by contacting other customers regarding their experience with the vendor," Keith said.

Nicole M. Allcock, director of pharmacy at SoutheastHEALTH, said the hospital had not purchased any medication from the compounding center.

"Our hearts go out to the families and patients who have been affected by this outbreak," Allcock said in a prepared statement. "SoutheastHEALTH takes alerts such as this very seriously. Southeast pharmacies and Southeast Hospital have not purchased any medications from the compounding pharmacy involved in the recent meningitis outbreak."

Drs. Terry Cleaver and Christopher Reis, pain management physicians at the Brain and Neurospine Clinic of Missouri LLC, said none of their medications have been recalled.

"We purchase all of our medications for spinal injections directly from pharmaceutical manufacturers through their authorized distributors," the doctors said. "Immediately after hearing of the outbreak, we were in communication with our distributors. We were informed that none of the steroids we have received have demonstrated any signs of contamination, nor are any of our medications being recalled."

Cleaver and Reis also pointed to the Centers for Disease Control and Prevention website as a good source to monitor which treatment facilities have been affected.

The injections are a common treatment for sciatica, which is pain from a slipped or ruptured disk that often radiates down the legs, and for spinal stenosis, an age-related narrowing of the spine sometimes caused by arthritis. It results in pain or weakness, usually in the neck and lower back.

Doctors often recommend injecting steroids into the spinal column for patients who don't get adequate pain relief from aspirin, ibuprofen or other common medicines that reduce inflammation. The injections also are often used when physical therapy doesn't work, or for patients whose pain is too great to even try physical therapy or other remedies.

"The worst complication is it may not work," Schafer said he tells patients.

Patsy Bivins of Sturgis, Ky., is worried about the two steroid injections she got in her lower back in August to treat chronic pain from stenosis and fibromyalgia. She got a call Thursday from the outpatient center where she was treated, warning that she might have been given the tainted drug.

"Before I got the shots I was really suffering," Bivins said. "It did help some. But now I don't know what to do." She added: "When I got the call I thought, 'Here's another thing.' I don't need nothing else wrong with me, especially that."

Doctors use a needle about 3 inches long to inject the drug into what is known as the epidural space surrounding the spinal cord.

Patients are typically middle-age or older. Often, three injections are given over a few weeks at pain clinics, surgery centers or hospitals. Such treatments can cost several hundred dollars and take about 10 minutes, and patients can go home afterward. The effects may last several months or longer, but patients often repeat the treatment after a year.

The drug involved in the outbreak, methylprednisolone acetate, is among the steroids commonly used in the procedure. Batches of the drug from other sources have not been implicated so far.

Some patients swear by the treatments, but the scientific evidence is mixed. Some studies have found the injections work no better than dummy medicines, while others have found benefits.

The injections work best for younger patients with fairly recent pain rather than chronic, debilitating pain that has lasted for several years, said Dr. Steven Cohen, an associate professor of anesthesiology at Johns Hopkins Medical School.

Southeast Missourian assistant managing editor Lucas Presson contributed to this story.