White Horehound : Safety, Interactions

by MedlinePlus

(Page 2 of 2)

Safety

Allergies

In theory, white horehound may cause an allergic reaction in persons with known allergy or hypersensitivity to members of the Lamiaceae family (mint family) or any white horehound components.

Side Effects and Warnings

White horehound is generally considered to be safe when used as a flavoring agent in foods. However, there is limited scientific study of safety, and most available information is from animal (not human) research. Reported side effects include rash at areas of direct contact with white horehound plant juice, abnormal heart rhythms, low blood pressure, and decreased blood sugar (seen in animals with high blood sugar). White horehound may cause vomiting and diarrhea. Caution is warranted in people with heart disease or gastrointestinal disorders. Caution may also advisable in persons with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare professional, and medication adjustments may be necessary.

Theoretically, white horehound may interfere with the body's response to the hormone aldosterone, which affects the ability of the kidneys to control the body's levels of water and electrolytes. These theoretical effects may cause high blood pressure, high blood sodium, low potassium, leg swelling, and muscle weakness. Individuals who have high or unstable blood pressure, high sodium, or low potassium or who are taking medications that reduce the amount of water in the body (diuretics, or "water pills") should use caution. White horehound may contain estrogen-like chemicals that either have stimulatory or inhibitory effects on estrogen-sensitive parts of the body. It is unclear what effects may occur in hormone-sensitive conditions such as some cancers (breast, ovarian, uterine) and endometriosis, or in people using hormone replacement therapy/birth control pills.

Pregnancy and Breastfeeding

White horehound is not recommended during pregnancy or breastfeeding. Animal studies suggest that white horehound may cause miscarriage.

Interactions

Interactions with Drugs

Because white horehound is thought to be an expectorant in the treatment of cough or congestion, its use with cold medications that have expectorant ingredients may cause added effects. Theoretically, white horehound may reduce the effects of some medications given for vomiting (serotonin receptor antagonist drugs such as granisetron and ondansetron), migraine headache (ergot alkaloids such as bromocriptine, dihydroergotamine, or ergotamine), and antidepressants that possess serotonin activity (selective serotonin reuptake inhibitors (SSRIs) like Prozac®, Paxil®, or Zoloft®). White horehound may interact with the ability of the body to excrete penicillin. The reported ability of white horehound to cause diarrhea may cause an excessive response when combined with stool softeners or laxatives.

Large amounts of white horehound may increase the risk of abnormal heart rhythms and should be avoided by people treated with drugs that affect heart rhythm. Animal studies suggest that use of white horehound with medications that lower blood pressure may cause a larger than expected drop in blood pressure. White horehound contains glycoside compounds that act on the heart, and these theoretically could affect the activity of glycoside medications such as digoxin (Lanoxin®). Theoretically, white horehound may increase the action of the hormone aldosterone on the kidneys, and it may interact with some diuretic medications.

Based on animal studies, white horehound may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional. Medication adjustments may be necessary. In theory, white horehound may also interact with medications used to treat thyroid disorders such as iodine, liothyronine (T3, Cytomel®); methimazole (Tapazole®); propylthiouracil (PTU); thyroxine (T4, Levoxyl®, Synthroid®); Thyrolar® (T4 plus T3).

White horehound may contain estrogen-like chemicals that either have stimulatory or inhibitory effects on estrogen-sensitive parts of the body. It is unclear what effects may occur in people using hormonal therapies such as birth control pills or hormone replacement therapy. Based on early animal study, white horehound may lower cholesterol or triglyceride blood levels and therefore may have additive effects with other drugs with similar actions.

Interactions with Herbs and Dietary Supplements

In theory, white horehound may lower blood pressure and may cause increased urine production. Caution is advised when using herbs or supplements that lower blood pressure or increase urination. Agents that may lower blood pressure include aconite/monkshood, arnica, baneberry, betel nut, bilberry, black cohosh, bryony, calendula, California poppy, coleus, curcumin, eucalyptol, eucalyptus oil, evening primrose oil, flaxseed/flaxseed oil, garlic, ginger, ginkgo, goldenseal, green hellebore, hawthorn, Indian tobacco, jaborandi, mistletoe, night blooming cereus, oleander, pasque flower, periwinkle, pleurisy root, shepherd's purse, Texas milkweed, turmeric, and wild cherry. Supplements that may increase urine production include artichoke, celery, corn silk, couchgrass, dandelion, elder flower, horsetail, juniper berry, kava, shepherd's purse, uva ursi, and yarrow.

White horehound may contain glycoside chemicals that affect the heart, and therefore should be used with caution by people taking other supplements that have glycoside ingredients. Such agents include adonis, balloon cotton, black hellebore root/melampode, black Indian hemp, bushman's poison, C actus grandifloris , convallaria, eyebright, figwort, foxglove/digitalis, frangipani, hedge mustard, hemp root/Canadian hemp root, king's crown, lily-of-the-valley, motherwort, oleander leaf, pheasant's eye plant, plantain leaf, pleurisy root, psyllium husks, redheaded cotton-bush, rhubarb root, rubber vine, sea-mango, senna fruit, squill, strophanthus, uzara, wallflower, wintersweet, yellow dock root, and yellow oleander. Notably, bufalin/Chan Suis is a Chinese herbal formula that has been reported as toxic or fatal when taken with cardiac glycosides.

Because white horehound may cause diarrhea, use caution if combining it with other laxative herbs, such as 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.

Animal studies suggest that white horehound may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment. Possible examples include: Aloe vera , American ginseng, bilberry, bitter melon, burdock,fenugreek, fish oil, gymnema, horse chestnut seed extract (HCSE), marshmallow, milk thistle, Panax ginseng, rosemary, Siberian ginseng, and stinging nettle.

Because white horehound may contain estrogen-like chemicals, the effects of other agents believed to have estrogen-like properties may be altered. Possible examples include alfalfa, black cohosh, bloodroot, burdock, flaxseed, hops, kudzu, licorice, pomegranate, red clover, soy, thyme, and yucca. Theoretically, white horehound may interact with agents that affect serotonin activity, such as antidepressant herbs or supplements with possible selective serotonin reuptake inhibitor properties, such as ephedra, evening primrose oil, fenugreek, Ginkgo biloba , hops, St. John's wort, tyrosine, valerian, or yohimbe. In theory, white horehound may interact with agents that affect the thyroid, such as bladderwrack. Based on early animal study, white horehound may lower cholesterol or triglyceride blood levels and therefore may have additive effects with other herbs and supplements with similar actions.

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