6 Types of Medications That Can Harm Your Kidneys

How they can affect kidneys: NSAIDs are normally safe for occasional use and should be used only as directed. If taken for too long, however, they can do damage by reducing blood flow to the kidneys.  If they’re taken when you’re dehydrated or when your blood pressure is low, they can cause acute kidney injury.  All OTC pain medications should be taken as directed on the label, but none should be taken for more than 10 days in a row for pain or three days in a row for fever.  If symptoms persist, speak with your health care team. Long-term use at high doses can cause chronic kidney damage by reducing blood flow to the kidneys.  Owen says that the ibuprofen OTC dose should not exceed 400mg (two of the 200mg pills) every 6 hours. The naproxen OTC dose should not exceed 220mg every 8 hours.

2.  Antibiotics

What they are: Antibiotics are medications that kill bacteria that cause infection.  They can be taken orally, topically or by injection, though for the most part topical medications have limited effects inside the body, says Owen. Some of the more common infections they fight are strep throat and urinary tract infections.  They’re not needed for all infections and should be used only when prescribed by a physician.

Examples: Some of the most common antibiotics include penicillin, amoxicillin, ciprofloxacin, doxycycline and azithromycin.

How they can affect the kidneys: If you have kidney disease, understand what your kidney function is before you take an antibiotic.  That will help you and your doctor determine the dosage.  Owen says that some medications used to treat viruses can cause kidney injury.  It’s important, he says, to stay hydrated when taking medications like acyclovir or valacyclovir.  When dehydrated, the medication can clump together and create crystals that prevent you from urinating properly, he says.

Some people, Owen says, may have allergic reactions to antibiotics in their kidneys. The reaction is sometimes just in the kidneys and at other times can cause a rash or a fever. Such a reaction in the kidneys is caused by inflammation and irritation. Owen stresses the importance of letting your health care team know if you have any changes in how much you urinate after any course of antibiotics.

If not taken as directed or in doses that are too high, antibiotics can be dangerous and more likely to cause problems. People with decreased kidney function should be taking smaller doses than others. 

3.   Laxatives

What they are: Laxatives are usually taken to alleviate constipation and to clean the bowel before a colonoscopy. Medications used to prepare for a colonoscopy require a prescription and are usually taken orally by tablets, capsules, powders, liquids or as suppositories.

Examples: Some of the most common OTC laxatives include bisacodyl (Dulcolax), senna (Senokot, Ex-Lax), docusate (Colace) and polyethylene glycol (Miralax).

How they can affect the kidneys: If taken as directed, most laxatives are safe for those without kidney problems. For those with kidney disease, it’s important to keep well hydrated by drinking lots of water and clear liquids. Dehydration can cause damage to the kidneys by decreasing blood flow to them.

Sometimes, overusing laxatives can cause kidney stones.  If you need to take laxatives multiple times a week to treat constipation, says Owen, check with your health care team to make sure it’s safe for you.

4.   Contrast dyes

What they are: Contrast dyes are either swallowed or injected for use in diagnostic tests such as CT scans, MRIs and angiograms to enhance images used for diagnosis and treatment.

Examples:  CT scans use iodine-based contrasts and MRIs use gadolinium-based contrasts.

How they can affect the kidneys:  While rare, contrast dyes used for scans can lead to serious kidney problems. Owen says that iodine contrast dye for CT scans can lead to contrast-induced nephropathy.  That means that the contrast dye can temporarily change how well the blood flows to and from the kidneys.  Gadolinium contrast dye used for MRIs, says Owen, can cause nephrogenic systemic fibrosis or a thickening or darkening of some spots on the skin.  He says this can happen when someone who already has kidney disease gets an MRI and advises that before getting an MRI or CT scan, your health care team should check your kidney function to make sure it’s safe.

5.  Acid Suppressants

What they are: Acid suppressants are used to prevent and treat heartburn and indigestion by reducing acid in the stomach and can be purchased both OTC and by prescription.

Examples: Some of the most common acid suppressants include omeprazole (Prilosec) and esomeprazole (Nexium), famotidine (Pepcid) and calcium carbonate (Tums).

How they can affect the kidneys:  Owen says that some acid suppressants can cause kidney inflammation and irritation.  Medications like omeprazole or esomeprazole should be taken only for short durations (less than a month), he says.  If you’re taking an acid suppressant for more than a month, speak with your health care team. If taking calcium carbonate (Tums) regularly to treat heartburn or indigestion, talk with your health care team to see if there are other options.

6.  Herbal Supplements

What they are:  Herbals can be a type of dietary supplement with therapeutic properties that are sold as tablets, capsules, powders, tea, extracts and as fresh or dried plants. Although many people use them because they believe they improve health, they don’t go through the kind of testing that’s required of drugs and can be potentially dangerous.

Examples:  A 2007 review of supplement-induced kidney dysfunction lists more than 15 herbs and supplements reported to have caused kidney problems, including chromium, creatine, licorice, willow bark, vitamin C and yohimbe. (See box for a list of supplements that should be avoided if you have kidney disease.)

How they can affect the kidneys:  Don’t assume that because they’re “natural” herbal supplements are always safe. Some can interact badly with prescription medication. Others can act as a diuretic or a water pill and can cause kidney irritation or damage. Multiple herbal supplements contain potassium and phosphorous, both of which may need to be limited in people with kidney disease, Owen says. Generally, people with kidney disease should not use herbal supplements without first speaking with a doctor or a pharmacist.