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 health care 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.

Licorice may reduce the effects of birth control pills, hormone replacement therapies, or testosterone therapy.

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. Examples include alder buckthorn, aloe dried leaf sap, black root, blue flag rhizome, butternut bark, dong quai, European buckthorn, eyebright, cascara bark, castor oil, chasteberry, colocynth fruit pulp, dandelion, gamboges bark, horsetail, jalap root, manna bark, plantain leaf, podophyllum root, psyllium, rhubarb, senna, wild cucumber fruit, and yellow dock root.

Herbs with potential diuretic properties may increase adverse effects associated with licorice. Examples include artichoke, celery, corn silk, couchgrass, dandelion, elder flower, horsetail, juniper berry, kava, shepherd's purse, uva ursi, and yarrow.

Herbs and supplements that lower blood pressure may add to the blood pressure lowering effects of licorice. Potential examples include aconite/monkshood, arnica, baneberry, betel nut, bilberry,black cohosh, bryony, calendula, California poppy, coleus, curcumin, eucalyptol, eucalyptus oil,flaxseed/flaxseed oil, garlic,ginger, ginkgo, goldenseal, green hellebore, hawthorn, Indian tobacco, jaborandi, mistletoe, night blooming cereus, oleander, pasque flower, periwinkle, pleurisy root, Polypodium vulgare , shepherd's purse, Texas milkweed, turmeric, and wild cherry.

Herbs with monoamine oxidase inhibitor activity may cause worse side effects when used at the same time as licorice. Herbs with possible monoamine oxidase inhibitor activity include 5-HTP (5-Hydroxytryptophan), California poppy, chromium, DHEA (Dehydroepiandrosterone), DLPA (DL Phenylalanine), ephedra, evening primrose oil, fenugreek, Ginkgo biloba , hops, mace, St. John's wort, SAMe (S-adenosylmethionine), sepia, tyrosine, valerian, vitamin B6, and yohimbe bark extract. 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. Multiple cases of bleeding have been reported with the use of Ginkgo biloba , and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases. Some examples include: alfalfa, American ginseng, angelica, anise, Arnica montana , asafetida, aspen bark, bilberry, birch, black cohosh, bladderwrack, bogbean, boldo, borage seed oil, bromelain, capsicum, cat's claw, celery, chamomile, chaparral, clove, coleus, cordyceps, danshen, devil's claw, dong quai, EPA (eicosapentaenoic acid, found in fish oils), evening primrose oil, fenugreek, feverfew, fish oil, flaxseed/flax powder (not a concern with flaxseed oil), ginger, grapefruit juice, grapeseed, green tea, guggul, gymnestra, horse chestnut, horseradish, lovage root, male fern, meadowsweet, nordihydroguairetic acid (NDGA), omega-3 fatty acids, onion, papain, panax ginseng, parsley, passionflower, poplar, prickly Ash, propolis, quassia, red clover, reishi, Siberian ginseng, sweet clover, rue, sweet birch, sweet clover, turmeric , vitamin E, white willow, wild carrot, wild lettuce, willow, wintergreen, and yucca.

Liver metabolism of certain herbs and supplements may be affected by licorice but further study is needed before a conclusion can be drawn.

Interactions with Laboratory Values

Licorice may decrease cortisol, ACTH, aldosterone, and potassium levels in the blood. Increases in renin and sodium levels have also been observed.

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Tags: Herbal Medicine

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