Why Does My Lower Back Hurt?
The pain may radiate down the front, side, or back of your leg, or it may be confined to the low back.
Pain in the lower back or low back pain is a common concern, affecting up to 80% of Americans at some point in their lifetime. Many will have more than one episode.
Low back pain is not a specific disease, rather it is a symptom that may occur from a variety of different processes. In up to 85% of people with low back pain, despite a thorough medical examination, no specific cause of the pain can be identified.
What causes pain in the lower back?
Back pain can have many underlying reasons, but often no specific cause will be found and the pain will stop. This chapter will review many of the causes of back pain and proper evaluation and diagnosis. Please be sure to discuss your individual symptoms as well as the suggested treatments with your health-care professional to determine the appropriate diagnostic and treatment plan for your circumstances.
- Low back pain is second only to the common cold as a cause of lost days at work. It is also one of the most common reasons to visit a doctor's office or a hospital's emergency department. It is the second most common neurologic complaint in the United States, second only to headache.
- For most people, even those with nerve root irritation, their symptoms will improve within two months no matter what treatment is used, even if no treatment is given.
- Doctors usually refer to back pain as acute if it has been present for less than a month and chronic if it lasts for a longer period of time.
Low Back Pain Symptoms and Signs
Pain in the lumbosacral area (lower part of the back) is the primary symptom of low back pain.
- The pain may radiate down the front, side, or back of your leg, or it may be confined to the low back.
- The pain may become worse with activity.
- Occasionally, the pain may be worse at night or with prolonged sitting such as on a long car trip.
- You may have numbness or weakness in the part of the leg that receives its nerve supply from a compressed nerve.
- This can cause an inability to plantar flex the foot. This means you would be unable to stand on your toes or bring your foot downward. This occurs when the first sacral nerve is compressed or injured.
- Another example would be the inability to raise your big toe upward. This results when the fifth lumbar nerve is compromised.
Nearly everyone has low back pain at some time during their life.
Low Back Pain Causes
Back pain is a symptom. Common causes of back pain involve disease or injury to the muscles, bones, and/or nerves of the spine. Pain arising from abnormalities of organs within the abdomen, pelvis, or chest may also be felt in the back. This is called referred pain. Many disorders within the abdomen, such as appendicitis, aneurysms, kidney diseases, kidney infection, bladder infections, pelvic infections, and ovarian disorders, among others, can cause pain referred to the back. Normal pregnancy can cause back pain in many ways, including stretching ligaments within the pelvis, irritating nerves, and straining the low back. Your doctor will have this in mind when evaluating your pain.
Picture of a herniated lumbar disc
- Nerve root syndromes are those that produce symptoms of nerve impingement (a nerve is directly irritated), often due to a herniation (or bulging) of the disc between the lower back bones. Sciatica is an example of nerve root impingement. Impingement pain tends to be sharp, affecting a specific area, and associated with numbness in the area of the leg that the affected nerve supplies.
- Herniated discs develop as the spinal discs degenerate or grow thinner. The jellylike central portion of the disc bulges out of the central cavity and pushes against a nerve root. Intervertebral discs begin to degenerate by the third decade of life. Herniated discs are found in one-third of adults older than 20 years of age. Only 3% of these, however, produce symptoms of nerve impingement.
- Spondylosis occurs as intervertebral discs lose moisture and volume with age, which decreases the disc height. Even minor trauma under these circumstances can cause inflammation and nerve root impingement, which can produce classic sciatica without disc rupture.
- Spinal disc degeneration coupled with disease in joints of the low back can lead to spinal-canal narrowing (spinal stenosis). These changes in the disc and the joints produce symptoms and can be seen on an X-ray. A person with spinal stenosis may have pain radiating down both lower extremities while standing for a long time or walking even short distances.
- Cauda equina syndrome is a medical emergency whereby the spinal cord is directly compressed. Disc material expands into the spinal canal, which compresses the nerves. A person would experience pain, possible loss of sensation, and bowel or bladder dysfunction. This could include inability to control urination causing incontinence or the inability to begin urination.
- Musculoskeletal pain syndromes that produce low back pain include myofascial pain syndromes and fibromyalgia.
- Myofascial pain is characterized by pain and tenderness over localized areas (trigger points), loss of range of motion in the involved muscle groups, and pain radiating in a characteristic distribution but restricted to a peripheral nerve. Relief of pain is often reported when the involved muscle group is stretched.
- Fibromyalgia results in widespread pain and tenderness throughout the body. Generalized stiffness, fatigue, and muscle aches are reported.
- Infections of the bones (osteomyelitis) of the spine are an uncommon cause of low back pain.
- Noninfectious inflammation of the spine (spondylitis) can cause stiffness and pain in the spine that is particularly worse in the morning. Ankylosing spondylitis typically begins in adolescents and young adults.
- Tumors, possibly cancerous, can be a source of skeletal pain.
- Inflammation of nerves from the spine can occur with infection of the nerves with the herpes zoster virus that causes shingles. This can occur in the thoracic area to cause upper back pain or in the lumbar area to cause low back pain.
As can be seen from the extensive but not all-inclusive list of possible causes of low back pain, it is important to have a thorough medical evaluation to guide possible diagnostic tests.
When to See a Doctor for Back Pain
The Agency for Healthcare Research and Quality has identified 11 red flags that doctors look for when evaluating a person with back pain. The focus of these red flags is to detect fractures (broken bones), infections, or tumors of the spine. Presence of any of the following red flags associated with low back pain should prompt a visit to your doctor as soon as possible for complete evaluation.
- Recent significant trauma such as a fall from a height, motor vehicle accident, or similar incident
- Recent mild trauma in those older than 50 years of age: A fall down a few steps or slipping and landing on the buttocks may be considered mild trauma.
- History of prolonged steroid use: People with asthma, COPD, and rheumatic disorders, for example, may be given this type of medication.
- Anyone with a history of osteoporosis: An elderly woman with a history of a hip fracture, for example, would be considered high risk.
- Any person older than 70 years of age: There is an increased incidence of cancer, infections, and abdominal causes of the pain.
- Prior history of cancer
- History of a recent infection
- Temperature over 100 F
- IV drug use: Such behavior markedly increases risk of an infectious cause.
- Low back pain worse at rest: This is thought to be associated with an infectious or malignant cause of pain but can also occur with ankylosing spondylitis.
- Unexplained weight loss
The presence of any of the above would justify a visit to a hospital's emergency department, particularly if your family doctor is unable to evaluate you within the next 24 hours.
- The presence of any acute nerve dysfunction should also prompt an immediate visit. These would include the inability to walk or inability to raise or lower your foot at the ankle. Also included would be the inability to raise the big toe upward or walk on your heels or stand on your toes. These might indicate an acute nerve injury or compression. Under certain circumstances, this may be an acute neurosurgical emergency.
- Loss of bowel or bladder control, including difficulty starting or stopping a stream of urine or incontinence, can be a sign of an acute emergency and requires urgent evaluation in an emergency department.
- If you cannot manage the pain using the medicine you are currently prescribed, this may be an indication for a reevaluation or to go to an emergency department if your doctor is not available. Generally, this problem is best addressed with the doctor writing the prescription who is overseeing your care.
Low Back Pain Exams and Tests
- Because many different conditions may cause back pain, a thorough medical history will be performed as part of the examination. Some of the questions you are asked may not seem pertinent to you but are very important to your doctor in determining the source of your pain.
- Your doctor will first ask you many questions regarding the onset of the pain. (Were you lifting a heavy object and felt an immediate pain? Did the pain come on gradually?) He or she will want to know what makes the pain better or worse. The doctor will ask you questions referring to the red flag symptoms. He or she will ask if you have had the pain before. Your doctor will ask about recent illnesses and associated symptoms such as coughs, fevers, urinary difficulties, or stomach illnesses. In females, the doctor will want to know about vaginal bleeding, cramping, or discharge. Pain from the pelvis, in these cases, is frequently felt in the back.
- To ensure a thorough examination, you will be asked to put on a gown. The doctor will watch for signs of nerve damage while you walk on your heels, toes, and soles of the feet. Reflexes are usually tested using a reflex hammer. This is done at the knee and behind the ankle. As you lie flat on your back, one leg at a time is elevated, both with and without the assistance of the doctor. This is done to test the nerves, muscle strength, and assess the presence of tension on the sciatic nerve. Sensation is usually tested using a pin, paper clip, broken tongue depressor, or other sharp object to assess any loss of sensation in your legs.
- Depending on what the doctor suspects is wrong with you, the doctor may perform an abdominal examination, a pelvic examination, or a rectal examination. These exams look for diseases that can cause pain referred to your back. The lowest nerves in your spinal cord serve the sensory area and muscles of the rectum, and damage to these nerves can result in inability to control urination and defecation. Thus, a rectal examination is essential to make sure that you do not have nerve damage in this area of your body.
- Doctors can use several tests to "look inside you" to get an idea of what might be causing the back pain. No single test is perfect in that it identifies the absence or presence of disease 100% of the time.
- If there are no red flags, there is often little to be gained in obtaining X-rays for patients with acute back pain. Because about 90% of people have improved within 30 days of the onset of their back pain, most doctors will not order tests in the routine evaluation of acute, uncomplicated back pain.
- Plain X-rays are generally not considered useful in the evaluation of acute back pain, particularly in the first 30 days. In the absence of red flags, their use is discouraged. Their use is indicated if there is significant trauma, mild trauma in those older than 50 years of age, people with osteoporosis, and those with prolonged steroid use. Do not expect an X-ray to be taken.
- Myelogram is an X-ray study in which a radio-opaque dye is injected directly into the spinal canal. Its use has decreased dramatically since MRI scanning. A myelogram now is usually done in conjunction with a CT scan and, even then, only in special situations when surgery is being planned.
- Magnetic resonance imaging (MRI) scans are a highly detailed test and are very expensive. The test does not use X-rays but very strong magnets to produce images. Their routine use is discouraged in acute back pain unless a condition is present that may require immediate surgery, such as with cauda equina syndrome or when red flags are present and suggest infection of the spinal canal, bone infection, tumor, or fracture.
- MRI may also be considered after one month of symptoms to rule out more serious underlying problems.
- MRIs are not without problems. Bulging of the discs is noted on up to 40% of MRIs performed on people without back pain. Other studies have shown that MRIs fail to diagnose up to 20% of ruptured discs that are found during surgery.
- A CT scan is an X-ray test that is able to produce a cross-sectional picture of the body. CT scan is used much like MRI.
- Electromyogram or EMG is a test that involves the placement of very small needles into the muscles. Electrical activity is monitored. Its use is usually reserved for more chronic pain and to predict the level of nerve root damage. The test is also able to help the doctor distinguish between nerve root disease and muscle disease.
Self-Care at Home for Back Pain
General recommendations are to resume normal, or near normal, activity as soon as possible. However, stretching or activities that place additional strain on the back are discouraged.
- Sleeping with a pillow between the knees while lying on one side may increase comfort. Some doctors recommend lying on your back with a pillow under your knees.
- No specific back exercises were found that improved pain or increased functional ability in people with acute back pain. Exercise, however, may be useful for people with chronic back pain to help them return to normal activities and work. These exercises usually involve stretching maneuvers.
- Nonprescription medications may provide relief from pain.
- Ibuprofen (Advil, Nuprin, or Motrin), available over the counter, is an excellent medication for the short-term treatment of low back pain. Because of the risk of ulcers and gastrointestinal bleeding, talk with your doctor about using this medication for a long time.
- Acetaminophen (Tylenol) has been shown to be as effective as ibuprofen in relieving pain.
- Topical agents such as deep-heating rubs have not been shown to be effective.
- Some people seem to benefit from the use of ice or heat. Their use, although not proven effective, is not considered to be harmful. Take care: Do not use a heating pad on "high" or place ice directly on the skin.
- Most experts agree that prolonged bed rest is associated with a longer recovery period. Further, people on bed rest are more likely to develop depression, blood clots in the leg, and decreased muscle tone. Very few experts recommend more than a 48-hour period of decreased activity or bed rest. In other words, get up and get moving to the extent you can.
Back Pain: 16 Back Pain Truths and Myths
Back Pain Medical Treatment
Initial treatment of low back pain is based on the assumption that the pain in about 90% of people will go away on its own in about a month. Many different treatment options are available. Some of them have been proven to work while others are of more questionable use. You should discuss all remedies you tried with your health-care provider.
Home care is recommended for the initial treatment of low back pain. Bed rest remains of unproven value, and most experts recommend no more than two days of bed rest or decreased activity. Some people with sciatica may benefit from two to fours days of rest. Application of local ice and heat provide relief for some people and should be tried. Acetaminophen and ibuprofen are useful for controlling pain.
- Many studies have called into question the usefulness of our present treatment of back pain. For any given person, it is not known if a particular therapy will provide benefit until it is tried. Your doctor may try treatments known to be helpful in the past.
Low Back Pain Medications
Medication treatment options depend on the precise diagnosis of the low back pain. Your doctor will decide which medication, if any, is best for you based on your medical history, allergies, and other medications you may be taking.
- Nonsteroidal anti-inflammatory medications (NSAIDs) are the mainstay of medical treatment for the relief of back pain. Ibuprofen, naproxen, ketoprofen, and many others are available. No particular NSAID has been shown to be more effective for the control of pain than another. However, your doctor may switch you from one NSAID to another to find one that works best for you.
- COX-2 inhibitors, such as celecoxib (Celebrex), are more selective members of NSAIDs. Although increased cost can be a negative factor, the incidence of costly and potentially fatal bleeding in the gastrointestinal tract is clearly less with COX-2 inhibitors than with traditional NSAIDs. Long-term safety (possible increased risk for heart attack or stroke) is currently being evaluated for COX-2 inhibitors and NSAIDs.
- Acetaminophen is considered effective for treating acute pain as well. NSAIDs do have a number of potential side effects, including gastric irritation and kidney damage, with long-term use.
- Muscle relaxants: Muscle spasm is not universally accepted as a cause of back pain, and most relaxants have no effect on muscle spasm. Muscle relaxants may be more effective than a placebo (sugar pill) in treating back pain, but none has been shown to be superior to NSAIDs. No additional benefit is gained by using muscle relaxants in combination with NSAIDs over using NSAIDs alone. Muscle relaxants cause drowsiness in up to 30% of people taking them. Their use is not routinely recommended.
- Opioid analgesics: These drugs are considered an option for pain control in acute back pain. The use of these medications is associated with serious side effects, including dependence, sedation, decreased reaction time, nausea, and clouded judgment. One of the most troublesome side effects is constipation. This occurs in a large percentage of people taking this type of medication for more than a few days. A few studies support their short-term use for temporary pain relief. Their use, however, does not speed recovery.
- Steroids: Oral steroids can be of benefit in treating acute sciatica. Steroid injections into the epidural space have not been found to decrease duration of symptoms or improve function and are not currently recommended for the treatment of acute back pain without sciatica. Benefit in chronic pain with sciatica remains controversial. Injections into the posterior joint spaces, the facets, may be beneficial for people with pain associated with sciatica. Trigger point injections have not been proven helpful in acute back pain. Trigger point injections with a steroid and a local anesthetic may be helpful in chronic back pain. Their use remains controversial.
Low Back Pain Surgery
Surgery is seldom considered for acute back pain unless sciatica or the cauda equina syndrome is present. Surgery is considered useful for people with certain progressive nerve problems caused by herniated discs.
- Spinal manipulation: Osteopathic or chiropractic manipulation appears to be beneficial in people during the first month of symptoms. Studies on this topic have produced conflicting results. The use of manipulation for people with chronic back pain has been studied as well, also with conflicting results. The effectiveness of this treatment remains unknown. Manipulation has not been found to benefit people with nerve root problems.
- Acupuncture: Current evidence does not support the use of acupuncture for the treatment of acute back pain. Scientifically valid studies are not available. Use of acupuncture remains controversial.
- Transcutaneous electric nerve stimulation (TENS): TENS provides pulses of electrical stimulation through surface electrodes. For acute back pain, there is no proven benefit. Two small studies produced inconclusive results, with a trend toward improvement with TENS. In chronic back pain, there is conflicting evidence regarding its ability to help relieve pain. One study showed a slight advantage at one week for TENS but no difference at three months and beyond. Other studies showed no benefit for TENS at any time. There is no known benefit for sciatica.
- Exercises: In acute back pain, there is currently no evidence that specific back exercises are more effective in improving function and decreasing pain than other conservative therapy. In chronic pain, studies have shown a benefit from the strengthening exercises. Physical therapy can be guided optimally be specialized therapists.
After your initial visit for back pain, it is recommended that you follow your doctor's instructions as carefully as possible. This includes taking the medications and performing activities as directed. Back pain will, in all likelihood, improve within several days. Do not be discouraged if you don't achieve immediate improvement. Nearly everyone improves within a month of onset of the pain.
Low Back Pain Prevention
The prevention of back pain is, itself, somewhat controversial. It has long been thought that exercise and an all-around healthy lifestyle would prevent back pain. This is not necessarily true. In fact, several studies have found that the wrong type of exercise such as high-impact activities may increase the chance of suffering back pain.
Nonetheless, exercise is important for overall health and should not be avoided. Low-impact activities such as swimming, walking, and bicycling can increase overall fitness without straining the low back.
- Specific exercises: Talk to your doctor about how to perform these exercises.
- Abdominal crunches, when performed properly, strengthen abdominal muscles and may decrease the tendency to suffer back pain.
- Although not useful to treat back pain, stretching exercises are helpful in alleviating tight back muscles.
- The pelvic tilt also helps alleviate tight back muscles.
- Lumbar support belts: Workers who frequently perform heavy lifting are often required to wear these belts. There is no proof that these belts prevent back injury. One study even indicated that these belts increased the likelihood of injury.
- Standing: While standing, keep your head up and stomach pulled in. If you are required to stand for long periods of time, you should have a small stool on which to rest one foot at a time. Do not wear high heels.
- Sitting: Chairs of appropriate height for the task at hand with good lumbar support are preferable. To avoid putting stress on the back, chairs should swivel. Automobile seats should also have adequate low-back support. If not, a small pillow or rolled towel behind the lumbar area will provide adequate support.
- Sleeping: Individual needs vary. If the mattress is too soft, many people will experience backaches. The same is true for sleeping on a hard mattress. Trial and error may be required. A piece of plywood between the box spring and mattress will stiffen a soft bed. A thick mattress pad will help soften a mattress that is too hard.
- Lifting: Don't lift objects that are too heavy for you. If you attempt to lift something, keep your back straight up and down, head up, and lift with your knees. Keep the object close to you, don't stoop over to lift. Tighten your stomach muscles to keep your back in balance.
Low Back Pain Prognosis
The prognosis for people with acute back pain associated with red flags (described above) depends on the underlying cause of the pain.
- Most people experience an episode of back pain without other health concerns, and their symptoms will go away on their own within a month. For about half, back pain may return.
- A majority of people with sciatica will eventually recover, with or without surgery. The recovery period is much longer than for uncomplicated, acute back pain.
- You can improve your chances of early recovery by staying active and avoiding more than two days of relative bed rest.
Reviewed on 8/18/2022
Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care
Image source: iStock Images
Klippel, John. Primer on the Rheumatic Diseases, 13th ed. New York: Springer, 2008.