Analgesic nephropathy Health Article

Definition

Analgesic nephropathy involves damage to one or both kidneys caused by overexposure to mixtures of medications, especially over-the-counter pain remedies (analgesics).

Alternative Names

Phenacetin nephritis; Nephropathy - analgesic

Causes, incidence, and risk factors

Analgesic nephropathy involves damage within the internal structures of the kidney. It is caused by long-term use of analgesics, especially over-the-counter (OTC) medications that contain phenacetin or acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin or ibuprofen.

The excessive use may equal about three pills per day for 6 years. This frequently occurs as a result of self-medicating, often for some type of chronic pain.

Analgesic nephropathy occurs in about 4 out of 100,000 people, mostly women over 30. The rate has decreased significantly since phenacetin is no longer widely available in OTC preparations.

Risk factors include:

• Use of OTC analgesics containing more than one active ingredient
• Chronic headache
• Chronic backache or musculoskeletal pain
• Emotional or behavioral changes
• History of dependent behaviors including smoking, alcoholism, and excessive use of tranquilizers
• Pain with menstrual periods

Persons with this condition may also have a history of the following conditions:

• Urinary tract infections (see acute UTI)
• Interstitial nephritis
• Renal calculi
• Prerenal azotemia
• Congestive heart failure
• Blood volume depletion (such as dehydration)

Symptoms

• Weakness
• Fatigue
• Increased urinary frequency or urgency
• Blood in the urine
• Flank pain or back pain, renal colic (occasional)
• Decreased urine output
• Decreased alertness
  • Drowsiness
  • Confusion, delirium
  • Lethargy
• Decreased sensation, numbness (especially of extremities)
• Nausea, vomiting
• Easy bruising or bleeding
• Swelling, generalized