Pain that lingers or recurs on one or both sides is the body’s way of signaling an underlying problem. Some common causes of pain on the left side of the body include infection and injury to internal organs, muscles, or nerves.

In some cases, this pain resolves on its own. However, other cases may require immediate medical intervention.

This article examines some conditions that can lead to pain on the left side of the body. It also looks at the treatment options available and when a person should contact a doctor.

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The spleen is an organ located in the upper left side of a person’s abdomen. It is an important part of the immune system, though people can live without one.

A person may experience pain on their left side when the spleen is injured or enlarged.

Damaged or ruptured spleen

A ruptured spleen is a medical emergency.

According to the National Health Service (NHS), an injury can cause the spleen to rupture. The rupture can occur immediately or weeks after the initial injury.

Symptoms can include:

  • pain behind the left ribs
  • tenderness
  • dizziness
  • rapid heart rate

Additionally, a person may feel pain at the top of their left shoulder if they lie down and raise their legs.

Enlarged spleen

An injury or infection can cause the spleen to become enlarged. This can also be a result of another health condition, such as rheumatoid arthritis, leukemia, or cirrhosis.

The NHS note that a person may not always experience symptoms. However, if symptoms do occur, a person might notice:

  • discomfort and pain behind the left ribs
  • bleeding easily
  • anemia
  • fatigue
  • feeling full quickly
  • infections

Treatment

A person will need to undergo surgery.

Learn more about the treatment options for an enlarged spleen here.

Diverticulosis is a condition wherein small pouches form and push through the weaker spots in the colon wall. Diverticulitis occurs when one or more of these pouches becomes inflamed.

The National Institute of Diabetes and Digestive and Kidney Diseases note that the pain typically occurs in the lower left side of the abdomen.

The pain is normally sudden and severe. However, it can also be mild and worsen over a period of a few days.

Symptoms include:

  • diarrhea
  • constipation
  • vomiting
  • nausea

Learn more about diverticulitis here.

Treatment

If the symptoms are mild, a person can rest, take antibiotics, and consume a liquid diet.

After a few days, if the symptoms ease, the person can gradually incorporate solid foods back into their diet.

If the symptoms are sudden and severe, the person may need to stay in the hospital for a few days and receive intravenous antibiotics.

Learn more about the best foods for diverticulitis here.

A heart attack occurs when an artery supplying blood to the heart becomes blocked. This blockage occurs due to a buildup of fatty deposits in the arteries.

Blocked arteries reduce oxygen supply to the heart, damaging the heart muscle and leading to a heart attack.

Pain in one or both arms may be a symptom of a heart attack, but some other important symptoms to look for include:

  • discomfort in the center of the chest
  • a feeling of squeezing pain or pressure in the arms, chest, or both
  • shortness of breath
  • cold sweat
  • lightheadedness

The American Heart Association (AHA) advise calling 911 or the nearest hospital in the event of these symptoms occurring. Many healthcare professionals consider the first hour of a heart attack the “golden hour,” during which timely treatment can save lives.

Treatment

Treatment for a heart attack typically includes surgery, medications, or a combination of the two.

Learn more about the treatment options for a heart attack here.

According to one 2020 article, sciatica is a painful condition that almost always only affects one side of the body. However, it can affect both sides of the body. This is called bilateral sciatica, which is rare.

It is named after the sciatic nerve, which extends from the spine to the legs and feet.

The most common cause of sciatica is a herniated or bulging spinal disk, which exerts pressure on the sciatic nerve.

People with sciatica define the pain as “knife-like” or a feeling of pins and needles.

Some other symptoms include:

  • numbness
  • sharp pain when sneezing or coughing
  • an inability to sit up straight
  • weakness
  • a burning sensation around the buttocks

A specialist will perform a physical examination and ask for the person’s medical history to make a diagnosis. They may also do an MRI test to confirm the diagnosis.

Treatment

Sciatica treatment includes resting, taking pain relievers, stretching, and, in some cases, physical therapy.

With proper care, most people recover within 3–6 weeks.

A buildup of gas in the colon can lead to pain on the left side of the body. The pain can also occur on the right side or on both sides.

Under normal circumstances, people pass gas through burping or passing it through the rectum. This is a routine process for the body. In fact, most people produce about 1–4 pints of gas per day and pass gas about 14–23 times per day.

Sometimes, gas accumulates in the digestive tract from swallowing excess air while eating or drinking. It can also accumulate due to the breakdown of undigested foods by intestinal bacteria.

Foods that can cause excess gas include carbonated beverages, sugar substitutes, and fiber supplements.

Other symptoms include:

  • frequent belching
  • flatulence
  • abdominal bloating
  • pain or discomfort on one or both sides of the body

Treatment

Treatment usually involves making changes to diet and lifestyle.

Learn more about easy remedies for gas here.

A doctor may also recommend over-the-counter (OTC) medications that aid digestion and reduce symptoms.

Learn more about the treatment of painful gas here.

A person can experience a strain or sprain on the left side of their body. However, it can also affect other parts of the body.

Although people may use these terms interchangeably, strains and sprains are two different conditions that affect different parts of the body.

The NHS note that it is likely to be a strain or sprain if the pain and other symptoms affect the:

  • ankle
  • wrist
  • foot
  • thumb
  • knee
  • leg
  • back

The National Institute of Arthritis and Musculoskeletal and Skin Diseases note that a sprain is a tear or twist of a ligament, which is an elastic tissue connecting one bone to another.

Symptoms of a sprain include:

A strain is an injury of the muscle or tendon. It can cause partial stretching and, in some cases, even tearing of the muscle or tendon.

To identify a strain, look for symptoms such as:

  • intense pain
  • muscle spasm
  • muscle weakness
  • swelling
  • cramping
  • difficulty moving

Learn more about the differences between a sprain and strain here.

Treatment

The American Academy of Orthopaedic Surgeons recommend similar treatments for sprains and strains. These are:

  • rest
  • ice
  • compression
  • elevation

A person may also need to perform gentle exercises and take OTC medications such as acetaminophen, ibuprofen, or naproxen.

A ruptured ovarian cyst causes pain that typically occurs on one side of the body.

An ovarian cyst is a fluid-filled sac that can develop inside, or on, an ovary. The Office on Women’s Health note that these are common and usually harmless.

Ovarian cysts can rupture. In some cases, they do not cause any symptoms, or they may cause mild symptoms. In other cases, the ruptured cyst can cause severe symptoms, such as sudden and severe pain in the lower belly. Bleeding can also occur.

Treatment

For milder symptoms, a healthcare professional may prescribe pain medications.

In more severe cases, a person may need surgery.

Testicular torsion typically causes pain on one side of the body.

Testicular torsion occurs when the testicle rotates. This can twist the spermatic cord, which brings blood to the scrotum. As a result, the reduced blood flow and cause pain and swelling.

Some symptoms include:

  • sudden and severe pain in the affected testicle
  • nausea
  • vomiting
  • abdominal pain
  • groin pain
  • a swollen testicle

It is important to note that it is possible for the pain to come on slowly. This may be over a period of hours or days. However, this is less common.

Treatment

Testicular torsion is a medical emergency. If a male does not receive treatment within 6 hours, their testicle can shrink and die.

They will need to undergo surgery.

A kidney infection can cause pain on either side or on both sides of the body.

The kidneys are located below the rib cage on either side of the spine. They perform many vital tasks, including:

  • filtering the blood
  • ridding the body of toxic waste
  • controlling blood pressure
  • maintaining fluid levels

However, these vital functions of the kidneys will be disrupted if an infection occurs.

A kidney infection typically occurs due to bacteria. Most kidney infections begin as a bladder infection.

Symptoms of a kidney infection include:

  • pain in the back, the side, or the groin region
  • fever
  • nausea
  • vomiting
  • cloudy or dark urine with an unpleasant smell
  • an increased need to urinate frequently
  • painful urination
  • chills

People with these symptoms should contact their doctor immediately.

Untreated kidney infections can lead to a life threatening condition called sepsis. As many as 30% of people with sepsis die every year.

Treatment

A doctor will prescribe antibiotics to treat a kidney infection.

Learn more about the treatment options for a kidney infection here.

If a person is experiencing any symptoms of a heart attack, they need medical attention immediately.

A person should also seek medical attention as soon as possible if they are experiencing any symptoms of a kidney infection. If they do not receive treatment, the infection can worsen and lead to sepsis.

In general, it is important to consult a doctor if the pain does not go away with home treatment or disrupts daily life.

Depending on a person’s symptoms and medical history, a doctor may recommend a visit to a specialist for a more thorough investigation.

Pain is one of the body’s signals that something is wrong. There are several types and causes of pain on the left side of the body.

Some of these conditions may resolve on their own with rest. Other cases may require medical treatment and long-term care.

The cause of the pain may be a disease or condition not included in the list above. It helps to be vigilant for other symptoms that accompany the pain and to report these to a doctor.

Try to assess the start and endpoint of the pain, its duration, and its triggers. This information will help the doctor make a more informed diagnosis.