licorice (generic name)
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Interactions with Drugs
In general, prescription drugs should be taken one hour before licorice or two hours after licorice because licorice may increase the absorption of many drugs. Increased absorption may increase the activities and side effects of some drugs (for example, nitrofurantoin). Phosphate salts have been shown to increase licorice absorption. Liver metabolism of certain drugs may be affected by licorice but further study is needed before a conclusion can be drawn.
Because the toxicity of digoxin (Lanoxin®) is increased when potassium levels are low, people who take digoxin and are interested in using licorice should discuss this with their healthcare provider. Increased monitoring may be necessary. Other drugs that may increase the tendency for irregular heart rhythms are also best avoided when using licorice.
Licorice may reduce the effects of blood pressure or diuretic (urine-producing) drugs, including hydrochlorothiazide and spironolactone. Use of licorice with the diuretics hydrochlorothiazide or furosemide (Lasix®) may cause potassium levels to fall very low and lead to dangerous complications. Other drugs that can also cause potassium levels to fall too low and are best avoided when using licorice include insulin, sodium polystyrene (Kayexalate®), and laxatives. Chewing tobacco may increase the toxicity of licorice gums by causing electrolyte disturbances.
Licorice may increase the adverse effects associated with corticosteroids such as prednisolone and monoamine oxidase inhibitors such as isocarboxazid (Marplan®), phenelzine (Nardil®), or tranylcypromine (Parnate®). Agents acting on serotonin may also interact with licorice.
In theory, licorice may increase the risk of bleeding when used with anticoagulants (blood thinners) or antiplatelet drugs. Examples include warfarin (Coumadin®), heparin, clopidogrel (Plavix®), or aspirin.
Interactions with Herbs and Dietary Supplements
Herbs with potential laxative properties may add to the potassium-lowering effects of licorice.
Herbs with potential diuretic properties may increase adverse effects associated with licorice.
Herbs and supplements that lower blood pressure may add to the blood pressure-lowering effects of licorice.
Herbs with monoamine oxidase inhibitor activity may worsen side effects when used at the same time as licorice. Agents acting on serotonin may also interact with licorice.
In theory, herbs and supplements that increase the risk of bleeding may further increase the risk of bleeding when taken with licorice.
Liver metabolism of certain herbs and supplements may be affected by licorice but further study is needed before a conclusion can be drawn.
Licorice may interact with herbs or supplements used for heart disorders. It may also interact with other herbs or supplements with hormonal effects.
This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): Tracee Rae Abrams, PharmD (University of Rhode Island); Ethan Basch, MD (Memorial Sloan-Kettering Cancer Center); Stephen Bent, MD (University of California, San Francisco); Tracy Ha, PharmD (Massachusetts College of Pharmacy); Dana A. Hackman, BS (Northeastern University); David Kroll, PhD (Duke University); Katie Nummy, BS (Northeastern University); Michael Smith, M.R.PharmS., ND (Canadian College of Naturopathic Medicine); David Sollars, MAc (Merrimack College); Isabel Sylesky, PharmD (Northeastern University); Phillipe Szapary, MD (University of Pennsylvania); Shaina Tanguay-Colucci, BS (Natural Standard Research Collaboration); Sarah Taylor, PharmD (University of Pittsburgh); Natasha Tiffany, MD, PhD (Harvard Medical School); Verda Tunaligil, MD, MPH (Harvard School of Public Health); Catherine Ulbricht, PharmD (Massachusetts General Hospital); Minney Varghese, BS (Northeastern University); Mamta Vora, PharmD (Natural Standard Research Collaboration); Wendy Weissner, BA (Natural Standard Research Collaboration); Peter Wolsko, MD (Harvard Medical School).