In the common presentation of acute low back pain, pain develops after movements that involve lifting, twisting, or forward-bending. The symptoms may start soon after the movements or upon waking up the following morning. The description of the symptoms may range from tenderness at a particular point to diffuse pain. It may or may not worsen with certain movements, such as raising a leg, or positions, such as sitting or standing. Pain radiating down the legs (known as sciatica) may be present. The first experience of acute low back pain is typically between the ages of 20 and 40. This is often a person's first reason to see a medical professional as an adult. Recurrent episodes occur in more than half of people with the repeated episodes being generally more painful than the first.

Other problems may occur along with low back pain. Chronic low back pain is associated with sleep problems, including a greater amount of time needed to fall asleep, disturbances during sleep, a shorter duration of sleep, and less satisfaction with sleep. In addition, a majority of those with chronic low back pain show symptoms of depression or anxiety.

Back pain may be classified by various methods to aid its diagnosis and management. The duration of back pain is considered in three categories, following the expected pattern of healing of connective tissue. Acute pain lasts up to 12 weeks, subacute pain refers to the second half of the acute period (6 to 12 weeks), and chronic pain is pain which persists beyond 12 weeks.

Back pain is pain in any region of the back. It is divided into neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) based on the segment affected. The lumbar area is the most common area for pain, as it supports most of the weight in the upper body. Episodes of back pain may be acute, sub-acute, or chronic depending on the duration. The pain may be characterized as a dull ache, shooting or piercing pain, or a burning sensation. Discomfort can radiate into the arms and hands as well as the legs or feet, and may include numbness, or weakness in the legs and arms.

Back pain can originate from the muscles, nerves, bones, joints or other structures in the spine. Internal structures such as the gallbladder, pancreas, aorta, and kidneys may also cause referred pain in the back.

Back pain is common, with about nine out of ten adults experiencing it at some point in their life, and five out of ten working adults having it every year. Some estimate up to 95% of Americans will experience back pain at some point in their lifetime. It is the most common cause of chronic pain, and is a major contributor of missed work and disability. However, it is rare for back pain to be permanently disabling. In most cases of herniated disks and stenosis, rest, injections or surgery have similar general pain resolution outcomes on average after one year. In the United States, acute low back pain is the fifth most common reason for physician visits and causes 40% of missed days off work. Additionally, it is the single leading cause of disability worldwide.

There are a number of ways to classify low back pain with no consensus that any one method is best. There are three general types of low back pain by cause: mechanical back pain (including nonspecific musculoskeletal strains, herniated discs, compressed nerve roots, degenerative discs or joint disease, and broken vertebra), non-mechanical back pain (tumors, inflammatory conditions such as spondyloarthritis, and infections), and referred pain from internal organs (gallbladder disease, kidney stones, kidney infections, and aortic aneurysm, among others). Mechanical or musculoskeletal problems underlie most cases (around 90% or more), and of those, most (around 75%) do not have a specific cause identified, but are thought to be due to muscle strain or injury to ligaments. Rarely, complaints of low back pain result from systemic or psychological problems, such as fibromyalgia and somatoform disorders.

Low back pain may be classified based on the signs and symptoms. Diffuse pain that does not change in response to particular movements, and is localized to the lower back without radiating beyond the buttocks, is classified as "nonspecific", the most common classification. Pain that radiates down the leg below the knee, is located on one side (in the case of disc herniation), or is on both sides (in spinal stenosis), and changes in severity in response to certain positions or maneuvers is "radicular", making up 7% of cases. Pain that is accompanied by red flags such as trauma, fever, a history of cancer or significant muscle weakness may indicate a more serious underlying problem and is classified as "needing urgent or specialized attention".

The symptoms can also be classified by duration as acute, sub-chronic (also known as sub-acute), or chronic. The specific duration required to meet each of these is not universally agreed upon, but generally pain lasting less than six weeks is classified as "acute", pain lasting six to twelve weeks is "sub-chronic", and more than twelve weeks is "chronic". Management and prognosis may change based on the duration of symptoms.

The thoracic spine begins at the base of the neck and extends to the middle of the trunk. Any pain in this area is considered "middle back pain".

The exact symptoms associated with middle back pain will depend upon the underlying cause. Most middle back pain is not serious in nature. However, it does tend to have more serious pathology associated with it than pain in the neck or low back. Symptoms can include pain, either locally near the spine or referred along area the corresponding nerve dermatome. Symptoms can also include numbness or pins and needles when nerve irritation or compression is involved. Weakness in the legs or loss of bowel or bladder control in the presence of thoracic spine pain can indicate spinal cord compression and should be investigated.

Thoracic spinal pain was significantly associated with: concurrent musculoskeletal pain; growth and physical; lifestyle and social; backpack; postural; psychological; and environmental factors. Specific risk factors identified in adolescents included age (being older) and poorer mental health.

The pain over the back is localized and does not radiate into the leg. It occurs suddenly and may be accompanied by muscle spasms. The pain is dull, aching type and decreases on rest. It may be aggravated with activity.

Most cases of back pain are related to issues in human musculoskeletal system and are not related to severe diseases. Musculoskeletal problems also called mechanical because many of them linked to vertebrae physical motions. Back pain itself is not considered a diagnosis, but rather a symptom of underlying (in most cases musculoskeletal) problems.

following:

- Vertebrae misalignment, which can cause nerve interference (also called subluxation), muscle tension, or muscle spasm

- Strained muscles

- Sprained ligaments

- Ruptured disks, which also called "slipped", or herniated disks

- Degenerative discs (lose their cushioning ability). The degeneration usually caused by repetitive strain, or injury, or aging.

- Irritated joints

Back strain (pulled back muscle) is the injury occurring to muscles or tendons. Due to back strain, the tendons and muscles supporting the spine are twisted or pulled. Chronic back strain occurs because of the sustained trauma and wearing out of the back muscles Acute back strain can occur following a single instance of over stressing of back muscles, as in lifting a heavy object. Chronic back strain is commoner than the acute type.

To avoid back strain it is important to bend the knees whenever you lift a heavy object – see partial squats.

The symptoms of facet joint syndrome depend almost entirely on the location of the degenerated joint, the severity of the damage and the amount of pressure that is being placed on the surrounding nerve roots. It's important to note that the amount of pain a person experiences does not correlate well with the amount of degeneration that has occurred within the joint. Many people experience little or no pain while others, with the exact same amount of damage, undergo chronic pain.

Additionally, in symptomatic facet syndrome the location of the degenerated joint plays a significant role in the symptoms that are experienced. People with degenerated joints in the upper spine will often feel pain radiating throughout the upper neck and shoulders. That said, symptoms primarily manifest themselves in the lumbar spine, since the strain is highest here due to the overlying body weight and the strong mobility. Affected persons usually feel dull pain in the cervical or lumbar spine that can radiate into the buttocks and legs. Typically, the pain is worsened by stress on the facet joints, e.g. by diffraction into hollow back (retroflexion) or lateral flexion but also by prolonged standing or walking.

Pain associated with facet syndrome is often called "referred pain" because symptoms do not follow a specific nerve root pattern and the brain can have difficulty localizing the specific area of the spine that is affected. This is why patients experiencing symptomatic facet syndrome can feel pain in their shoulders, legs and even manifested in the form of headaches.

Radicular pain, or radiculitis, is pain "radiated" along the dermatome (sensory distribution) of a nerve due to inflammation or other irritation of the nerve root (radiculopathy) at its connection to the spinal column. A common form of radiculitis is sciatica – radicular pain that radiates along the sciatic nerve from the lower spine to the lower back, gluteal muscles, back of the upper thigh, calf, and foot as often secondary to nerve root irritation from a spinal disc herniation or from osteophytes in the lumbar region of the spine.

Psychogenic pain, also called psychalgia, is physical pain that is caused, increased, or prolonged by mental, emotional, or behavioral factors.

Headache, back pain, or stomach pain are some of the most common types of psychogenic pain. It may occur, rarely, in persons with a mental disorder, but more commonly it accompanies or is induced by social rejection, broken heart, grief, lovesickness, or other such emotional events.

Sufferers are often stigmatized, because both medical professionals and the general public tend to think that pain from psychological source is not "real". However, specialists consider that it is no less actual or hurtful than pain from other sources.

The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, "or described in terms of such damage"" (emphasis added). In the note accompanying that definition, the following can be found about pain that happens for psychological reasons:

Many people report pain in the absence of tissue damage or any likely pathophysiological cause; usually this happens for psychological reasons. There is usually no way to distinguish their experience from that due to tissue damage if we take the subjective report. If they regard their experience as pain and if they report it in the same ways as pain caused by tissue damage, it should be accepted as pain.

Medicine refers also to psychogenic pain or psychalgia as a form of chronic pain under the name of "persistent somatoform pain disorder" or "functional pain syndrome". Causes may be linked to stress, unexpressed emotional conflicts, psychosocial problems, or various mental disorders. Some specialists believe that psychogenic chronic pain exists as a protective distraction to keep dangerous repressed emotions such as anger or rage unconscious.

It remains controversial, however, that chronic pain might arise purely from emotional causes. Treatment may include psychotherapy, antidepressants, analgesics, and other remedies that are used for chronic pain in general.

Musculoskeletal disorders (MSDs) are injuries or pain in the human musculoskeletal system, including the joints, ligaments, muscles, nerves, tendons, and structures that support limbs, neck and back. MSDs can arise from a sudden exertion (e.g., lifting a heavy object), or they can arise from making the same motions repeatedly repetitive strain, or from repeated exposure to force, vibration, or awkward posture. Injuries and pain in the musculoskeletal system caused by acute traumatic events like a car accident or fall are not considered musculoskeletal disorders. MSDs can affect many different parts of the body including upper and lower back, neck, shoulders and extremities (arms, legs, feet, and hands). Examples of MSDs include carpal tunnel syndrome, epicondylitis, tendinitis, back pain, tension neck syndrome, and hand-arm vibration syndrome.

Orchialgia is long-term pain of the testes. It is considered chronic if it has persisted for more than 3 months. Orchialgia may be caused by injury, infection, surgery, cancer or testicular torsion and is a possible complication after vasectomy. IgG4-related disease is a more recently identified cause of chronic orchialgia.

One author describes the syndromes of chronic testicular pain thus:"The complaint is of a squeezing deep ache in the testis like the day after you got kicked there, often bilateral or alternating from one side to the other, intermittent, and, most commonly, associated with lower back pain. Sometimes it feels like the testicle is pinched in the crotch of the underwear but trouser readjustment does not help. There may also be pain in the inguinal area but no nausea or other symptoms. Back pain may be concurrent or absent and some patients have a long history of low back pain. Onset of pain is commonly related to activity that would stress the low back such as lifting heavy objects. Other stresses that might cause low back pain are imaginative coital positions, jogging, sitting hunched over a computer, long car driving, or other such positions of unsupported seating posture that flattens the normal lumbar lordosis curve."

MSDs can arise from the interaction of physical factors with ergonomic, psychological, social, and occupational factors.

Electroanalgesia is a form of analgesia, or pain relief, that uses electricity to ease pain. Electrical devices can be internal or external, at the site of pain (local) or delocalized throughout the whole body. It works by interfering with the electric currents of pain signals, inhibiting them from reaching the brain and inducing a response; different from traditional analgesics, such as opiates which mimic natural endorphins and NSAIDS (non-steroidal anti-inflammatory drugs) that help relieve inflammation and stop pain at the source. Electroanalgesia has a lower addictive potential and poses less health threats to the general public, but can cause serious health problems, even death, in people with other electrical devices such as pacemakers or internal hearing aids, or with heart problems.

Radiculopathy, also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly (a neuropathy). This can result in pain (radicular pain), weakness, numbness, or difficulty controlling specific muscles.

In a radiculopathy, the problem occurs at or near the root of the nerve, shortly after its exit from the spinal cord. However, the pain or other symptoms often radiate to the part of the body served by that nerve. For example, a nerve root impingement in the neck can produce pain and weakness in the forearm. Likewise, an impingement in the lower back or lumbar-sacral spine can be manifested with symptoms in the foot.

The radicular pain that results from a radiculopathy should not be confused with referred pain, which is different both in mechanism and clinical features.

"Polyradiculopathy" refers to the condition where more than one spinal nerve root is affected.

A combination of postural changes, the growing baby, unstable pelvic joints under the influence of pregnancy hormones, and changes in the centre of gravity can all add to the varying degrees of pain or discomfort. In some cases it can come on suddenly or following a fall, sudden abduction of the thighs (opening too wide too quickly) or an action that has strained the joint.

PGP can begin as early as the first trimester of pregnancy. Pain is usually felt low down over the symphyseal joint, and this area may be extremely tender to the touch. Pain may also be felt in the hips, groin and lower abdomen and can radiate down the inner thighs. Women suffering from PGP may begin to waddle or shuffle, and may be aware of an audible clicking sound coming from the pelvis. PGP can develop slowly during pregnancy, gradually gaining in severity as the pregnancy progresses.

During pregnancy and postpartum, the symphyseal gap can be felt moving or straining when walking, climbing stairs or turning over in bed; these activities can be difficult or even impossible. The pain may remain static, e.g., in one place such as the front of the pelvis, producing the feeling of having been kicked; in other cases it may start in one area and move to other areas. It is also possible that a woman may experience a combination of symptoms.

Any weight bearing activity has the potential of aggravating an already unstable pelvis, producing symptoms that may limit the ability of the woman to carry out many daily activities. She may experience pain involving movements such as dressing, getting in and out of the bath, rolling in bed, climbing the stairs or sexual activity. Pain may also be present when lifting, carrying, pushing or pulling.

The symptoms (and their severity) experienced by women with PGP vary, but include:

- Present swelling and/or inflammation over joint.

- Difficulty lifting leg.

- Pain pulling legs apart.

- Inability to stand on one leg.

- Inability to transfer weight through pelvis and legs.

- Pain in hips and/or restriction of hip movement.

- Transferred nerve pain down leg.

- Can be associated with bladder and/or bowel dysfunction.

- A feeling of the symphysis pubis giving way.

- Stooped back when standing.

- Malalignment of pelvic and/or back joints.

- Struggle to sit or stand.

- Pain may also radiate down the inner thighs.

- Waddling or shuffling gait.

- Audible ‘clicking’ sound coming from the pelvis.

Facet syndrome (also commonly known as facet joint disease, facet osteoarthritis, facet hypertrophy or facet arthritis) is a syndrome in which the facet joints (synovial diarthroses, from C2 to S1) degenerate to the point of causing painful symptoms. In conjunction with degenerative disc disease, a distinct but functionally related condition, facet syndrome is believed to be one of the most common causes of lower back pain.

A chronic, persistent low back pain along with buttock pain is the most important presentation. Radicular pain is observed.

Prior to the 20th century, specialists of pregnancy-related PGP used varying terminologies. It is now referred to as Pregnancy Related Pelvic Girdle Pain that may incorporate the following conditions:

- Diastasis of the Symphysis Pubis(DSP)

- Symphysis pubis dysfunction(SPD)

- Pelvic Joint Syndrome

- Physiological Pelvic Girdle Relaxation

- Symptom Giving Pelvic Girdle Relaxation

- Posterior Pelvic Pain

- Pelvic Arthropathy

- Inferior Pubic Shear/ Superior Pubic Shear /Symphyseal Shear

- Symphysiolysis

- Osteitis pubis (usually postpartum)

- Sacroiliitis

- One-sided Sacroiliac Syndrome /Double Sided Sacroiliac Syndrome

- Hypermobility

""The classification between hormonal and mechanical pelvic girdle instability is no longer used. For treatment and/or prognosis it makes no difference whether the complaints started during pregnancy or after childbirth." Mens (2005)"

In some cases, an audible snapping or popping noise as the tendon at the hip flexor crease moves from flexion (knee toward waist) to extension (knee down and hip joint straightened). After extended exercise pain or discomfort may be present caused by inflammation of the iliopsoas bursae. Pain often decreases with rest and diminished activity. Symptoms usually last months or years without treatment and can be very painful.

While ligamentous laxity may be genetic and affect an individual from a very early age, it can also be the result of an injury. Injuries, especially those involving the joints, invariably damage ligaments either by stretching them abnormally or even tearing them.

Loose or lax ligaments in turn are not capable of supporting joints as effectively as healthy ones, making the affected individual prone to further injury as well as compensation for the weakness using other parts of the body. Afflicted individuals may improve over time and lose some of their juvenile hyperlaxity as they age. Individuals over age 40 often have recurrent joint problems and almost always suffer from chronic pain. Back patients with ligamentous laxity in the area of the spine may also experience osteoarthritis and disc degeneration.

In the case of extreme laxity, or hypermobility, affected individuals often have a decreased ability to sense joint position, which can contribute to joint damage. The resulting poor limb positions can lead to the acceleration of degenerative joint conditions. Many hypermobility patients suffer from osteoarthritis, disorders involving nerve compression, chondromalacia patellae, excessive anterior mandibular movement, mitral valve prolapse, uterine prolapse and varicose veins.

The sciatic nerve (; also called "ischiadic nerve", "ischiatic nerve", "butt nerve") is a large nerve in humans and other animals. It begins in the lower back and runs through the buttock and down the lower limb. It is the longest and widest single nerve in the human body, going from the top of the leg to the foot on the posterior aspect. The sciatic nerve provides the connection to the nervous system for nearly the whole of the skin of the leg, the muscles of the back of the thigh, and those of the leg and foot. It is derived from spinal nerves L4 to S3. It contains fibers from both the anterior and posterior divisions of the lumbosacral plexus.

TOS affects mainly the upper limbs, with signs and symptoms manifesting in the shoulders, neck, arms and hands. Pain can be present on an intermittent or permanent basis. It can be sharp/stabbing, burning, or aching. TOS can involve only part of the hand (as in the pinky and adjacent half of the ring finger), all of the hand, or the inner aspect of the forearm and upper arm. Pain can also be in the side of the neck, the pectoral area below the clavicle, the armpit/axillary area, and the upper back (i.e., the trapezius and rhomboid area). Discoloration of the hands, one hand colder than the other hand, weakness of the hand and arm muscles, and tingling are commonly present.

TOS is often the underlying cause of refractory upper limb conditions like frozen shoulder and carpal tunnel syndrome that frequently defy standard treatment protocols. TOS can be related to Forward head posture.

A painful, swollen and blue arm, particularly when occurring after strenuous physical activity, could be the first sign of a subclavian vein compression related with an unknown TOS and complicated by thrombosis (blood clots), the so-called Paget–Schroetter syndrome or effort-induced thrombosis.

TOS can be related to cerebrovascular arterial insufficiency when affecting the subclavian artery. It also can affect the vertebral artery, in which case it could produce vision disturbances, including transient blindness, and embolic cerebral infarction.

TOS can also lead to eye problems and vision loss as a circumstance of vertebral artery compression. Although very rare, if compression of the brain stem is also involved in an individual presentation of TOS, transient blindness may occur while the head is held in certain positions.

If left untreated, TOS can lead to neurological deficits as a result of the hypoperfusion and hypometabolism of certain areas of the brain and cerebellum.