Back pain affects almost all adults at some point in their lives. While muscle injuries are often the cause, pain can also stem from organs like the kidneys, pancreas, or uterus. 

Someone with lower back pain can feel it over the entire back, but — depending on its cause — it may be concentrated on the left side of the lower back. Knowing the causes of lower back pain on the left side can help you better identify when it’s an emergency.

This article from HealthTap explains what may cause back pain on the left side, how a doctor might diagnose it, and how to know if it’s an emergency. 

Potential causes of lower back pain on the left side 

The lower back contains many different structures, such as bones, muscles, joints, and various organs. There are many potential causes of pain in this region. 

However, some causes are more common than others. Here are some of the more common causes of low back pain on the left side. It’s important to consult a doctor in order for them to diagnose any of these conditions. 

1. Muscle strain

A muscle strain is a type of injury to a muscle or a tendon, which is the tissue that connects muscles to bones. 

A strain can either cause a muscle or tendon to overstretch or to tear, which can lead to inflammation and pain. A strain can also cause stiffness and spasms. 

Lower back muscle strains often result from strenuous activities, like lifting something heavy without using the proper technique. Muscle strains in the lower back are also common symptoms following car accidents, sports injuries, or putting the body into awkward positions. 

Pain from muscle strains typically comes on suddenly and may be accompanied by swelling, redness, and bruising. A muscle strain usually heals on its own, but the time it takes to heal depends on the severity. Healing time can range from a few days to several months. 

2. Spondylolysis

Spondylolysis is a stress fracture affecting the vertebrae (the bones that make up the spine). 

A stress fracture is a tiny crack (or several) that affects the bone. Repetitive force, such as the kind resulting from constantly running long distances, can cause fractures. Although less common, stress fractures can develop from normal use of a bone that’s especially weak, such as in those with osteoporosis.

Spondylolysis may heal on its own within two or three months. However, it may cause severe pain, so doctors often recommend applying ice/heat, stretching, and over the counter pain medication as needed for those with the condition. 

3. Sacroiliac joint dysfunction

The sacroiliac (SI) joint links the pelvis to the lower part of the spine. Pain in the SI joint is primarily due to inflammation, or a change in the normal movement of the joint, which can stem from too much or too little movement. 

SI joint pain can occur on one or both sides of the body. But more often, it affects one side of the lower back. 

While some SI joint dysfunction may go away by itself, some people might require treatment that addresses improper movement, such as physical therapy. 

4. Sciatica

Sciatica refers to pain in the sciatic nerve, which originates at the base of the spine and passes through the glutes and down the leg, sometimes all the way to the foot. 

Pain from sciatica is typically described as sharp, intense, and electric, radiating to the entire leg. It may worsen with long periods of sitting or staying in the same position. 

Sciatica usually resolves on its own within one or two months. It’s best to see a specialist for any sciatica pain that persists or recurs for a long period of time.

5. Herniated disk

Disks cushion the vertebrae, which are the bones that make up the spine. Disks are made of a gelatinous material that allows the spine's bones to rotate without rubbing against each other. 

Sometimes, a disk may be pushed out of place by excessive physical activity. When a disk shifts out of place like this, it’s called “herniated.” 

When a disk is displaced, it can put pressure on surrounding nerves, resulting in pain. It’s also possible to experience tingling, numbness, or weakness in one or both legs. 

A herniated disk can occur in any part of the spine, but it’s more common in the lower spine. 

For most people, a herniated disc will get better on its own. But if the condition gets worse, then they made need surgery. 

6. Arthritis 

Arthritis describes inflammation, swelling, and pain in the joints — which are soft structures connecting the bones. Arthritis commonly affects the lower back, which may result in pain in the left side or the right side of the back.

Arthritis does not go away on its own. Treating arthritis can include medication, hot and cold therapy, massage, and acupuncture. Some evidence also suggests that dietary interventions can help to manage arthritis pain. 

7. Kidney stones

Kidney stones are hard mineral deposits, such as calcium, that form inside the kidneys. They can form due to dehydration, high mineral consumption, and lack of physical exercise. 

Kidney stones are sharp and rigid. When they reach the urinary tract, they can lead to severe pain. 

Since the kidneys are on each side of the lower back, patients can experience pain from kidney stones on the left side or the right side of the low back. People usually develop kidney stones only in one kidney, leading to one-sided pain. 

Other kidney stone symptoms include blood in the urine, nausea, vomiting, fever, and chills. 

Most kidney stones will pass on their own through the urinary tract (in the urine). However, if the stones are large, doctors may need to perform a procedure to break them up and make them easier to pass. 

8. Kidney infection

A kidney infection usually happens when a urinary tract infection (UTI) in the bladder goes untreated. Bacteria from the infection can enter the kidneys, leading to inflammation, swelling, and pain. 

Because the kidneys are in the lower back, a kidney infection can cause pain in this region—on either the right or left side of the back. 

Pain from a kidney infection may initially feel dull but progress into pain that’s sharp and stabbing. Other kidney infection symptoms may include painful urination, poor urine output, foul-smelling urine, blood in the urine, weakness, fever and chills, and nausea and vomiting. 

A kidney infection will not go away on its own. 

An untreated kidney infection can quickly become a life-threatening emergency. Patients who experience kidney infection symptoms should seek urgent care as soon as possible. 

9. Pancreatitis

The pancreas is an organ that makes insulin — a hormone that helps the body use food for energy. The condition is called pancreatitis, when the pancreas becomes inflamed. Because of its location, pancreatitis initially causes pain in the abdomen, which may move to the lower back.  

Pancreatitis can be acute, causing sudden pain, or it may slowly develop over time. Other symptoms of pancreatitis can include stomach pain, nausea and vomiting, and fever. 

The most common causes of pancreatitis include alcohol abuse and gallstones, which are hard lumps that can block the pancreatic duct. Treatment for the condition may involve antibiotics, painkillers, and dietary changes. 

10. Endometriosis

Endometriosis happens when uterine tissue (the endometrium) grows outside of the uterus. This tissue can gradually build up over time and lead to pain in the pelvis, stomach, and lower back.

Lower back pain from endometriosis can be on both sides of the back or only on the left side. 

Pain from endometriosis typically gets worse during menstruation. It can include a host of other symptoms, which include: 

• Heavy menstrual bleeding.
• Severe menstrual cramping. 
• Abdominal pain. 
• Pelvic pain. 
• Pain during sexual intercourse.
• Bleeding between periods. 
• Fatigue.
• Weakness.
• Dizziness.
• Fertility issues. 

The symptoms of endometriosis may be hard to diagnose because they’re very similar to other abdominal or digestive problems, so the condition is often misdiagnosed and mistreated in primary care. Women who experience symptoms of endometriosis should seek care from a women’s health provider. 

11. Pregnancy

Expecting mothers can experience low back pain during any trimester of their pregnancy. 

Pregnancy is associated with weight gain, hormonal changes, and changes in posture. These factors contribute to low back pain in different ways.

Weight gain puts extra pressure on the pelvic muscles, which support the lower back. Overloaded pelvic muscles may not offer as much lower back support, increasing back pain. 

Hormonal changes contribute to back pain in another way. When a woman gets pregnant, certain hormones get released that loosen the ligaments in the pelvic area, offering less support to the lower back.

Poor posture can also lead to back pain. Due to weakening abdominal muscles, weight gain, and a growing belly, many pregnant women experience changes in their posture.

Pregnant women are also more susceptible to urinary tract infections (UTIs), which can lead to kidney infections. During pregnancy, kidney infections are usually more dangerous and the treatment may be more complicated. For this reason, pregnant women should see a doctor as soon as they experience any possible symptoms of a kidney infection. 

12. Testicular torsion 

Testicular torsion is a condition that affects only men. It affects the spermatic cord, which is a structure that carries blood to the testicles. 

Testicular torsion causes the spermatic cord to twist, cutting blood flow to the testicles. This can make the scrotum (the sac that contains the testicles) swell up, leading to groin pain, which may radiate to the left lower back. 

Even though testicular torsion is rare, it is considered a medical emergency. If a doctor doesn’t address this condition quickly, it can cause irreversible damage to the testicles. Seeking emergency care is necessary if symptoms of testicular torsion show up. 

When is lower left back pain an emergency? 

In many cases, lower left back pain is mild or moderate, and will go away on its own with home care. However, in some cases, back pain can be a sign of a medical emergency. 

Those who develop sudden and severe pain in the lower back should assume that it’s an emergency and seek medical care as soon as possible. 

Even if the pain isn’t severe, it's important to seek emergency medical attention if they also have symptoms such as fever, chills, muscle weakness, numbness in the arms or legs, or dizziness.

How is lower back pain on the left side treated?

The treatment for lower back pain depends on the underlying cause. Only a doctor can diagnose and determine the underlying cause. 

A doctor will take a full medical history to diagnose patients with low back pain while asking about current and past symptoms. They may also order some tests, which can include: 

• A CT scan or MRI to check the muscles, joints, tendons, and other soft tissue in the back.

• An X-ray to check the bones in the spine for signs of fracture or conditions such as osteoporosis.

If the underlying cause is soft tissue damage, the healthcare provider may recommend a combination of over-the-counter (OTC) painkillers, heat and ice therapy, and physical therapy. For more serious conditions, they may recommend surgery. 

If the bones are affected, a doctor may recommend rest with medication to relieve pain and stabilize bone density. 

Conditions such as pregnancy or endometriosis may require a referral to a women’s health provider. 

Home care for lower back pain

Patients can often manage lower back pain at home with self-care. 

Some common home remedies include:

• Thermotherapy
  Thermotherapy is anything that increases soft tissue temperature, promoting circulation. It can be as simple as applying a heating pad to the lower back or taking a warm bath. 
• Cryotherapy
  Cryotherapy is the opposite of thermotherapy because it uses cold temperatures to speed up healing. Cryotherapy options, such as applying an ice pack or taking a cold shower, can reduce inflammation and speed healing. 
• Over-the-counter (OTC) pain relievers and other painkillers
  Acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs), like aspirin and ibuprofen, are non-prescription pain medications that can produce quick pain relief. Although most people don’t experience severe side effects from these medications, they do have risks and shouldn’t be a long-term therapy. It’s always best to consult a doctor before taking any OTC medications. Muscle relaxants, prescription steroids, and other treatment options may also help alleviate lumbar spine pain in some cases. These treatments require a doctor visit and prescription.
• Gentle movement
  Being sedentary can reduce circulation and interfere with healing. On the other hand, gentle movement, like stretching, may help bring back pain relief. 

Finding lower back pain relief with HealthTap 

If you experience lower back pain on the left side of your back, it may result from a back injury, muscle strain or other more serious conditions. Professional medical advice can help determine the most effective treatment.

HealthTap can connect you with a low-cost healthcare provider from the comfort of your home.

Schedule your virtual visit today.