Yellow dock is an herb that's used medicinally for the properties contained in its roots, as well as sometimes its leaves. If you have certain skin conditions, indigestion, constipation or other gastrointestinal problems, taking yellow dock root may help due to its laxative effects and astringent tannins. Yellow dock root may cause certain side effects, which are most common when you take too much of the herb or take it for a prolonged period of time.
Gastrointestinal Side Effects
The most common side effect that you may experience from taking yellow dock root is diarrhea or loose stools, says the University of Michigan Health System. Diarrhea is a typical side effect in any laxative medication or herb like yellow dock. Prolonged use or high doses of yellow dock can cause other gastrointestinal-related side effects, such as stomach cramps or pain, nausea and vomiting, warns the University of Pittsburgh Medical Center. The recommended dosage of yellow dock is 2/5- to 4/5-teaspoon (2 to 4 grams) of the dried root, 1/5- to 2/5-teaspoon (1 to 2 mL) of the tincture or 2/5- to 3/5-teaspoon (2 to 4 mL) of the liquid extract. If you have intestinal obstructions, you shouldn't take yellow dock because of the risk of complications. Yellow dock also contains anthraquinones, which may pass through breast milk and cause diarrhea in infants who are nursing from mothers taking the herb, notes Drug Digest.
Bladder & Kidney Stones
Overuse of yellow dock root could cause bladder or kidney stones, or possibly kidney failure, warns the University of Pittsburgh Medical Center. These potential side effects are due to yellow dock's oxalic acid content, which can harm the kidneys and liver. If you're prone to bladder or kidney stones, or if you have liver or kidney problems, you should avoid taking yellow dock root or leaves. The oxalic acid contained in yellow dock binds to calcium in the body, accumulating and forming into kidney and bladder stones, Drug Digest explains. The oxalic acid may also worsen gout due to these crystals' effects on the joints.
Allergic Reactions & Poisoning
Ingesting high amounts of yellow dock could result in poisoning. Also, you may experience an allergic reaction to yellow dock root, particularly if you're allergic to ragweed, Drug Digest warns. Only one case of yellow dock poisoning that was fatal has been reported, notes the University of Pittsburgh Medical Center.
Low Potassium Levels
If you overuse yellow dock root, you may experience low potassium levels. Taking yellow dock for long periods of time or in high doses can cause decreased potassium levels in your body through the loss of excessive amounts of potassium, says the University of Pittsburgh Medical Center. When your body has low potassium levels, you may experience irregular heartbeat, low blood pressure or muscle weakness, Drug Digest notes.