You may perceive herbal supplements as safer than prescription or over-the-counter medications, but this is not necessarily true. Many herbs have serious side effects, especially if your kidneys don't work well and don't filter out potentially harmful substances. Herbs may also interfere with medications you take to treat kidney disease. If you plan to take herbal supplements, ask your doctor if they're safe.
Poor Testing and Regulation
Medications in the United States must undergo thorough testing to prove their safety and effectiveness. Under the 1994 Dietary Supplements Health and Education Act, herbs are considered safe until proved harmful, kidney specialist Stephen Z. Fadem, M.D. explains. The amount of herb in a supplement can also vary.Your kidneys may excrete a small amount of an herb without difficulty but may not be able to filter a larger amount, which means dangerous amounts of the herb may stay in your body. Some herbs, such as Black Pearl, a patent remedy in Traditional Chinese Medicine, also contain large amounts of contaminants such as lead and cadmium, which can build up in your system, especially if your kidneys don't function well.
Medication Interactions
Many kidney patients take medications that could interact with herbal supplements. Herbs could either block the action of a drug, making it ineffective, or could potentiate its effects, causing too strong of an effect. Herbs known to interact with medications include ginkgo, ginger, garlic, echinacea, St. John's wort and blue cohosh, the National Kidney Foundation warns.
Possible Side Effects
Poor kidney function means your kidneys can't remove the harmful ingredients in an herb as effectively as healthy kidneys do. More of a drug or herb stays in your system, possibly building up to toxic levels. Many herbs are safe at low doses but toxic at higher doses. Herbs with diuretic properties such as bucha leaves, goldenrod, parsley, uva ursi and juniper berries could increase the burden on your kidneys. When you have decreased kidney function, you may retain potassium. Herbs that raise potassium levels such as alfalfa and dandelion could increase your potassium to dangerous levels, causing potentially fatal heart arrhythmias.
Harmful Herbs
Some herbs are harmful to the kidney whether or not you have kidney damage, but can worsen harm if your kidneys already function poorly. Herbs known to have harmful kidney effects include horse chestnut, autumn crocus and wormwood, according to the National Kidney Foundation. Herbs harmful if you have chronic kidney disease include aloe, bayberry, ginger, ginkgo, licorice, mate and rhubarb.
References
- National Kidney Foundation: Use of Herbal Supplements in Chronic Kidney Disease
- American Association of Kidney Patients; Are Herbal Products Risky for Chronic Kidney Disease Patients?; Stephen Fadem, M.D., et al.; May 2002
- National Kidney Foundation of Michigan; Facts about Drugs, Herbs & Other Things That Can Damage Your Kidneys; January 2003
- acuneeds Australia: Black Pearl
