Epidural steroid injections (ESIs) are generally safe as a short-term pain treatment, but repeated use over months or years can produce side effects that extend well beyond the injection site. Because the steroid enters your bloodstream regardless of where it’s injected, the long-term risks look surprisingly similar to those of oral steroids: bone thinning, hormonal disruption, blood sugar spikes, and mood changes. Current guidelines cap ESIs at four sessions per spinal region in a 12-month period, largely to limit these cumulative effects.
Bone Density Loss and Fracture Risk
Corticosteroids accelerate bone breakdown and slow bone rebuilding. A large retrospective study comparing over 3,400 patients who received at least one ESI with 3,000 patients who did not found that injections increased fracture risk by a factor of 1.21 after adjusting for other variables. That may sound modest, but it compounds with each additional injection and becomes more significant if you already have risk factors for osteoporosis, such as being postmenopausal, having a small frame, or taking other medications that weaken bone.
The concern is greatest in the lumbar spine, where ESIs are most commonly performed and where compression fractures are already common in older adults. If you’re receiving repeated injections over several years, a bone density scan can help you and your doctor weigh the ongoing benefit against skeletal risk.
Adrenal Suppression
Your adrenal glands produce cortisol, the body’s natural stress hormone. When you receive a synthetic steroid through an epidural, your brain detects the spike and dials down its own cortisol production. This suppression of the hormonal feedback loop occurs in most patients who receive ESIs and typically lasts about three weeks after a single injection.
For people who get injections repeatedly over six months or longer, the risk of meaningful adrenal insufficiency rises. In one preliminary study of 17 patients on long-term ESI regimens, about 12% developed adrenal insufficiency that persisted beyond the expected recovery window. Symptoms can include fatigue, muscle weakness, dizziness, and nausea, particularly during physical stress or illness when your body needs extra cortisol and can’t produce it.
Blood Sugar Disruption
If you have diabetes, this is one of the most immediate and practically important effects. Blood glucose rises an average of 106 mg/dL on the evening of the injection day in diabetic patients, and that elevation remains statistically significant for about three days. Even in people without diabetes, glucose and insulin levels increase noticeably within 24 hours, though they typically normalize within a week.
A single spike may be manageable with careful monitoring and medication adjustments, but repeated injections several times a year mean repeated disruptions to blood sugar control. For people with poorly controlled diabetes, this pattern can meaningfully worsen long-term glucose management.
Mood and Sleep Changes
Steroids affect the brain, not just the body. The psychiatric effects of corticosteroids range from insomnia and irritability to depression, mania, and in rare cases psychosis. The route of administration, whether oral or injected, does not seem to change the likelihood of these effects.
At doses roughly equivalent to what’s used in many ESIs, mood disturbances occur in about 1% to 5% of patients. Higher steroid doses push the rate higher: research from the Boston Collaborative Drug Surveillance Program found psychiatric disturbances in 1.3% of patients receiving lower doses, 4.6% at moderate doses, and 18.6% at the highest doses. In a large screening study of over 2,000 patients, fewer than 1% developed mood or psychotic symptoms that persisted for at least seven days. Most people experience nothing more than a few nights of poor sleep, but those with a history of mood disorders should be aware of the possibility.
Menstrual Irregularities
Roughly half of premenopausal women who receive a steroid injection notice some disruption to their next menstrual cycle. In a study of 77 women, about 51% reported changes: some had periods arrive up to four weeks late, others had them come early by as much as 20 days, and many noticed heavier or lighter bleeding than usual. These changes are temporary and typically resolve within one or two cycles, but they can be alarming if you aren’t expecting them, and they’re worth knowing about if you’re tracking fertility.
Vision Changes
A rare but notable side effect is a condition called central serous chorioretinopathy, where fluid builds up under the retina. It typically affects one eye and causes blurry, distorted vision, with objects appearing smaller than they are. Bright lights may also become uncomfortable. This has been reported after epidural, inhaled, topical, and joint-injected steroids, not just oral ones. The exact mechanism isn’t fully understood, but it’s thought to relate to cortisol’s effects on the blood vessels in the eye. The condition usually resolves after steroid exposure ends, though repeated episodes can cause lasting damage.
Infection Risk
Serious infections like spinal epidural abscess are uncommon but carry severe consequences. The incidence of infection after epidural procedures is roughly 1 in 2,000. Symptoms of an epidural abscess include escalating back pain, fever, and progressive neurological symptoms like leg weakness or numbness. This is a medical emergency. The risk increases with repeated procedures, immunosuppression, and diabetes, since the steroids themselves temporarily suppress local immune function.
Rare Neurological Complications
The most serious potential complication is spinal cord injury from impaired blood flow. This risk is concentrated in a specific type of ESI called a transforaminal injection, where the needle is placed near the nerve root. The vast majority of reported cases of spinal cord damage involved particulate steroid formulations, which are suspensions that can clump and block small blood vessels. Non-particulate formulations (solutions rather than suspensions) carry a lower risk, and many practitioners now use them exclusively for cervical spine injections. The FDA has issued safety communications about this risk, and guidelines recommend against using particulate steroids in certain injection approaches, particularly in the neck.
Adhesive arachnoiditis, a chronic inflammatory condition of the membranes surrounding the spinal cord, has been discussed as a potential complication. However, the evidence links it primarily to older preservatives and contrast agents rather than to the preservative-free steroid preparations used in modern practice.
How Frequency Limits Reduce Risk
Medicare guidelines limit ESIs to four sessions per spinal region in any rolling 12-month period, with at least 14 days between injections to assess whether the previous one worked. These limits exist specifically because the long-term side effects described above are cumulative. Each injection adds to your total steroid exposure for the year, and the risks to bone, adrenal function, and blood sugar don’t reset between sessions.
If an initial injection doesn’t provide meaningful relief, a second attempt may use a different approach, spinal level, or medication. But if two or three injections fail to help, continuing the same treatment adds risk without benefit. The 14-day waiting period also matters because it takes that long to fully gauge whether the steroid has reduced inflammation at the target site.