Analgesics and your kidney: Facts to know

Many analgesics should not be used if there is decreased kidney function, because they reduce the blood flow to the kidney. Also, long term use with higher doses may harm normal kidneys. It is important to realize that, while helpful, these medicines are not completely without risk, and they should be used carefully. Kidney disease related to analgesics is preventable.

What are analgesics?

Analgesics are medicines that help to control pain and reduce fever, and some types also decrease inflammation. Examples of analgesics that are available over the counter are: aspirin, paracetamol, acetaminophen, ibuprofen, Ketoprofen and naproxen sodium. Prescription strength pain medicines are also available. Some analgesics contain a combination of painkilling ingredients in one pill- such as aspirin, acetaminophen and caffeine- that have been linked to kidney disease. These are not as readily available as in the past.

Can analgesics hurt kidneys?

Check with your doctor to be sure you can use these medicines safely, particularly if you have kidney disease. Heavy or long-term use of some of these medicines, such as ibuprofen, naproxen, and higher dose aspirin, can cause chronic kidney disease known as chronic interstitial nephritis. The warning labels on over-the-counter analgesics tell you not to use these medicines for more than l0 days for pain and more than three days for fever. If you have pain and/or fever for a longer time, you should see your doctor. The doctor can check for possible medical problems and advise you about what medications you should take.

If you have decreased kidney function, painkillers called NSAIDs (see below) and higher dose aspirin are not recommended. Even with normal kidney function, you should use analgesics:

• Exactly as prescribed or as on the label
• At the lowest dose possible
• For the shortest period of time

Is aspirin safe for regular use?

When taken as directed, regular use of aspirin does not seem to increase the risk of kidney disease in people who have normal kidney function. However, taking doses that are too large (usually more than six or eight tablets a day) may temporarily- and possibly permanently- reduce kidney function. In people with kidney disease, aspirin may increase the tendency to bleed. People who already have reduced kidney function, or other health problems such as liver disease or severe heart failure, should not use aspirin without speaking to their doctor.

My doctor recommended that I take an aspirin every day to prevent heart attacks. Will this hurt my kidneys?

No. There is no evidence of risk regarding the regular use of aspirin in the small doses recommended for prevention of heart attacks. Use of a ‘baby aspirin’ (81-162 mg daily) is fine, even with reduced kidney function.

What analgesics are safe for people who have kidney disease?

Acetaminophen remains the drug of choice for occasional use in patients with kidney disease because of bleeding complications that may occur when these patients use aspirin. However, kidney patients who need to use acetaminophen habitually should be supervised by their doctors and be sure to avoid drinking alcohol while on this medicine.

What are NSAIDs? Are they safe to take?

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a specific group of pain relievers. Some NSAIDs are available over the counter. This includes different brands of ibuprofen, naproxen sodium and ketoprofen.

NSAIDs are usually safe for occasional use when taken as directed, but if you have known decreased kidney function, they should be avoided. These medications should only be used under a doctor’s care by patients with kidney disease, heart disease, high blood pressure or liver disease or by people who are over 65 or who take diuretic medications. NSAIDs may cause an increased risk of sudden kidney failure and even progressive kidney damage.

I have arthritis. What pain relievers can I take that won’t hurt my kidneys?

You should speak to your doctor about the best choice for you. In addition, if you have any of the medical conditions listed in the previous question, you should only use NSAIDs under your doctor’s supervision.

How do I know if analgesics have affected my kidneys?

Your doctor can check your kidneys by doing a simple blood test called a serum creatinine level. This test measures the amount of a waste product in your blood that is normally removed by your kidneys. If your kidneys are not working as well as they should, the creatinine level will be increased in your blood. The results of the serum creatinine test can be used to estimate your glomerular filtration rate (GFR). Your GFR number tells your doctor how much kidney function you have.

A urine test for the presence of protein may also be done. Persistent protein in the urine may be an early indication of kidney damage.

Are there other side effects from taking aspirin and NSAIDs?

Yes. The development of stomach ulcers and gastrointestinal bleeding has been the most common serious side effect from taking NSAIDs and aspirin. NSAIDs also increase the risk of heart attack and stroke.

What can I do to keep my kidneys healthy?

Kidney disease caused by analgesics is often preventable Here are some things you can do to help keep your kidneys healthy.

• Do not use over-the-counter pain relievers more than 10 days for pain or more than three days for fever. If you have pain or fever for a longer time, you should see your doctor
• Avoid prolonged use of analgesics that contain a mixture of painkilling ingredients, like aspirin, acetaminophen and caffeine mixtures in one pill
• If you are taking analgesics, increase the amount of fluid you drink to six to eight glasses a day
• If you are taking analgesics, avoid drinking alcohol
• If you have kidney disease, consult your doctor before taking an analgesic, particularly NSAIDs and higher dose aspirin.
• Use NSAIDs under your doctor’s supervision if you have heart disease, high blood pressure, kidney disease or liver disease or if you take diuretic medications or are over 65 years of age
• Make sure your doctor knows about all medicines you are taking, even over-the-counter medicines
• Make sure you read the warning label before using any over-the-counter analgesics.

Source: US National Kidney Foundation