What Organ Is on the Upper Left Side of Your Back?

What organ is on the upper left side of your back? Several sit close by: the back of the left lung, the spleen, the upper part of the left kidney, part of the stomach and the tail of the pancreas. Which one matters depends on exactly where you feel something, and pain in this area is very often caused by muscles or the spine rather than an organ.

Organs near the upper left back

Your torso is packed tightly, and some organs sit toward the back. Here is a plain-English tour, starting from the top.

• Left lung: The rear surface of the lung lies behind the rib cage, so lung or pleural problems can be felt in the upper back, often worse when you breathe in.
• Heart and aorta: The heart is mostly at the front, slightly left, but pain from it can be felt in the back, shoulder or arm. The aorta, the main artery, runs down in front of the spine.
• Spleen: Found under the lower left ribs, towards the side and back. It filters blood and supports immunity.
• Left kidney: The kidneys sit on either side of the spine, protected by the lower ribs. The left one is slightly higher than the right, so kidney pain is typically felt in the flank, below the ribs.
• Stomach: The upper part lies on the left, partly behind the lower ribs, so stomach issues can cause discomfort that spreads to the back.
• Pancreas: The tail of the pancreas extends toward the spleen on the left. Pancreatic problems sometimes cause pain that bores through to the back.
• Adrenal gland and colon: The left adrenal gland sits on top of the kidney, and the splenic flexure of the colon is nearby.

Where exactly is the pain?

Location gives useful clues, although it cannot replace an examination.

Where you feel it	Possible source	Other clues
Between the shoulder blade and spine	Muscle strain or spinal joints	Worse with movement or posture
Behind the ribs, worse on breathing in	Lung lining or rib joint	Sharp pain, sometimes cough
Under the lower left ribs	Spleen, stomach or kidney area	May involve fullness or nausea
Side of back below the ribs	Kidney	Fever, urinary symptoms
Deep pain that goes through to the back	Pancreas	Upper abdominal pain, nausea

Common non-organ causes

Doctors see far more musculoskeletal pain than organ disease. Typical causes include:

• Muscle strain from lifting, sport or unusual activity
• Poor posture, especially long hours at a desk or on a phone
• Joint irritation where the ribs meet the spine
• Trapped or irritated nerves
• Stress and tension in the shoulders and neck
• Shingles, which can cause burning pain before a rash appears

Pain from muscles usually changes with movement, pressing on the area or stretching. Organ pain is more often constant, unrelated to position, or accompanied by other symptoms.

Warning signs: when to get help quickly

Call 999 or go to A&E if upper back pain comes with chest pain or pressure, shortness of breath, pain spreading to the jaw or arm, sudden severe tearing pain, fainting, or confusion. These can signal a heart attack, a blood clot or an aortic problem. Contact your GP or NHS 111 promptly if you have a high temperature, pain on passing urine, blood in your urine, unexplained weight loss, persistent vomiting, yellowing skin, or pain that wakes you at night and does not ease. The NHS website has detailed symptom pages.

What you can do at home for mild pain

1. Keep moving gently; long bed rest tends to make back pain last longer.
2. Use a heat pack or warm bath to relax tight muscles.
3. Take simple pain relief such as paracetamol if suitable for you, following the packet instructions; ask a pharmacist if you have other conditions or take other medicines.
4. Adjust your desk set-up and take regular breaks to stand and stretch.
5. Try gentle shoulder rolls and shoulder blade squeezes.
6. See a doctor if it has not improved after a couple of weeks.

If your question was really about the lower part of the back, our guides to organs in the lower back on the left side and lower back left side organs cover that region in more detail.

How doctors work out the cause

A doctor will usually ask about when the pain began, what makes it better or worse and any other symptoms. They examine your back, chest and abdomen, and may check blood pressure and oxygen levels. Depending on what they find, they may arrange blood tests, a urine test, an X-ray, an ultrasound or other scans. Most people with back pain need no scans at all, as the cause is evident from the history and examination.

Frequently asked questions

Conclusion

The upper left side of your back sits close to the lung, spleen, kidney, stomach and pancreas, but muscle and joint problems cause most pain there. Notice what else you feel, take sensible steps at home for mild pain, and do not delay seeking help if you have any warning signs.