Licorice root is one of the most popular medicinal herbs used in modern naturopathy. As an herbalist, I recommend deglycyrrhizinated licorice for people coping with ulcers, heartburn, and certain hormone imbalances. Although deglycyrrhizinated licorice is generally safe when used as directed, under the guidance of a health care provider, it can cause several side effects– particularly when combined with certain herbs, supplements and medications.
Licorice supplements interact dangerously with several other medicinal herbs. As a general rule, you should not combine herbal supplements with one another unless a qualified health care provider recommends the combination, since they can cause unpredictable and hazardous interactions. Here are some herbs that you should not use if you are taking licorice supplements.
Foxglove
Also known as digitalis, foxglove is a plant that acts as both a very potent medicine and a poison. When used by prescription– as an FDA-approved medicine called Crystodigi– foxglove is safe and effective. However, homemade digitalis preparations can cause severe heart damage. Because licorice can also stress the heart, the two herbs should never be combined.
Aloe Vera
Topical aloe vera, used mostly to treat burns, is perfectly safe for people using licorice supplements. Oral aloe vera, on the other hand, is not. Aloe vera supplements can act as powerful laxatives, upsetting the balance of electrolytes such as potassium and sodium. Licorice can also reduce electrolyte levels, so it should not be used in combination with aloe vera.
Cascara Sagrada
Like aloe vera, cascara sagrada is a strong stimulant laxative capable of depleting levels of potassium. Licorice also reduces potassium levels, and the combination of both herbs could cause a serious interaction. Severe declines in potassium levels can cause fatigue, heart problems, disorientation and even death.
Senna
Another popular herbal laxative, senna causes bowel movements by irritating the lining of the bowels and causing the expulsion of waste. Large doses of senna can cause diarrhea, which can in turn cause the loss of electrolytes. Because of this side effect, senna is not appropriate for people using licorice. The two herbs could lead to potassium deficiency when used in combination with one another.
Rhubarb
The leaves and stems of the rhubarb plant are highly effective stimulant laxatives, but can cause several side effects for the bowels and heart. Like licorice, rhubarb reduces potassium levels and may damage the liver, kidneys and heart. Both herbs are relatively safe when used in isolation, but should not be used together.
Castor Oil
Derived from the castor bean, castor oil is an extremely powerful laxative that acts as both a stimulant-laxative and bowel lubricant. It causes a near-complete flush of the bowels within just minutes after consumption. Potassium deficiency is one common side effect associated with castor oil, and licorice could greatly increase the risk of this serious side effect. Do not take castor oil if you are also taking licorice.
Always consult a qualified physician who is familiar with holistic medicine before combining multiple medcinal herbs. The National Institutes of Health offers more information about the licorice root’s safety, efficacy and interactions.