Many conditions can cause back pain on the side or flank pain. According to the University of Maryland Medical Center, flank pain is pain that manifests on the side of the torso, between the upper abdomen and the back. Flank pain can indicate underlying kidney problems, although some causes of flank pain may be due to more benign conditions. Structures in or around the flank may cause flank pain, or flank pain may arise from problems in other parts of the body.
Acute Pancreatitis
Acute pancreatitis can cause flank pain. According to MayoClinic.com, pancreatitis, including acute and chronic pancreatitis, is inflammation of the pancreas. The pancreas is a long, flat gland and organ located behind the stomach in the upper abdomen. The pancreas' principle responsibility is to produce digestive enzymes and hormones that participate in blood sugar regulation. Acute pancreatitis appears suddenly and usually lasts for several days. Some cases of pancreatitis may self-resolve, while more severe cases may lead to life-threatening health complications. Common signs and symptoms associated with acute pancreatitis include abdominal, flank and back pain, abdominal pain that worsens with eating, abdominal pain that's lessened by curling into a fetal position, nausea, vomiting and abdominal tenderness. MayoClinic.com states that breathing problems, diabetes and infection are possible complications of pancreatitis.
Obstructive Nephropathy
Obstructive nephropathy can cause back pain on the side. The Penn State Milton S. Hershey Medical Center states that obstructive nephropathy is a kidney condition or abnormality caused by a complication of obstructive uropathy--a condition in which urine is blocked from flowing through the bladder and urethra. Obstructive nephropathy occurs in both men and women, although men with enlarged prostates or prostate cancer have a greater likelihood of developing this condition. Obstructive nephropathy may be caused by bladder tumors, prostate tumors, urinary tract strictures or narrowing, kidney stones or bladder stones. Common signs and symptoms associated with obstructive nephropathy include flank pain, increased or decreased urine output, difficulty initiating urination and dribbling after urinating. Other possible signs and symptoms include burning with urination, blood in the urine and other changes in the color of a person's urine.
Muscle Strain
Muscle strains can cause back pain on the side. Muscle strains are common injuries that involve a stretching or tearing of muscle fiber or tendon--a fibrous cord that joins a muscle belly with a bone. The lower back and posterior thigh muscles or hamstrings are common locations for muscle strains, although strains can occur in any part of the body, including the flank. Common signs and symptoms associated with muscle strains include pain and swelling in the affected area, muscles spasms around the injury site and reduced flexibility or active range of motion in the involved muscle. Most muscle strains can initially be treated using conservative care methods such as RICE--rest, ice, compression and elevation. After the initial phase of recovery, other therapeutic modalities can be used to speed healing, such as instrument-assisted soft tissue mobilization, massage, cold laser therapy and kinesio taping procedures.
