Interstitial nephritis is a disorder in which the tubules in your kidneys become inflamed and swollen. This limits their ability to reabsorb water and nutrients from your blood and filter out wastes to flush out of your body. 

There are two types of interstitial nephritis:

• Acute interstitial nephritis (AIN) comes on suddenly and is temporary in duration.
• Chronic interstitial nephritis is long-term and progressive.

Learn more about interstitial nephritis and its causes, symptoms, and treatment options.*

What causes interstitial nephritis?

Interstitial nephritis is most often caused by allergies to, or side effects from, certain drugs, including:

• Antibiotics, such as penicillin
• Diuretics and uric acid reducers
• Long-term use of pain relievers, such as acetaminophen (Tylenol), aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs) 

Other causes include systemic conditions, such as:

• Autoimmune disorders 
• Infections
• Insufficient potassium in your blood
• Too much calcium or uric acid in your blood

What are the symptoms of interstitial nephritis?

Depending on the severity of the condition, symptoms may include:

• Hematuria (blood in the urine)
• Fever
• Increased or decreased urination
• Drowsiness and confusion
• Nausea and vomiting
• Rash
• Edema (swelling) of feet, legs, hands, or other body parts
• Weight gain from fluid retention 
• Elevated blood pressure

In rare cases, the condition can lead to kidney failure and/or coma. Older adults are at higher risk for allergic reactions and severe symptoms, due to their more frequent use of multiple medications over long periods of time.

How is interstitial nephritis diagnosed?

The diagnostic process begins with a detailed medical history intake, particularly concerning any medications or supplements you are taking, and a physical examination by your physician. 

These are followed by clinical tests, which may include any of the following:

• Urinalysis
• Blood chemistry
• Arterial blood gases
• Blood urea nitrogen (BUN) and blood creatinine levels
• Complete blood count (red blood cells, white blood cells, and platelets)
• Abdominal ultrasound
• Kidney biopsy

How is interstitial nephritis treated?

Interstitial nephritis is usually a temporary, short-term disorder. Treatment for the condition is guided by its cause. 

In the case of a drug allergy or side effects, simply discontinuing that medication may be all that is required to reverse the condition and return your kidney function to normal. Your doctor may also prescribe anti-inflammatory drugs, like corticosteroids.

Limiting your sodium, protein, and fluid intake is a way to support your kidney health, reduce water retention swelling, and lower your blood pressure. Salt and fluid in the diet can improve swelling and high blood pressure. 

If kidney damage has occurred, you may need to go on dialysis, either temporarily or permanently, depending on the extent of the damage.

Call your doctor immediately if you develop or have symptoms of interstitial nephritis, especially if you notice a decrease in your urine output or feel confused and sluggish.

*Interstitial Nephritis. (2019, Jul. 16). Medline Plus. https://medlineplus.gov/ency/article/000464.htm