- Humulus lupulus L.
- 2-methy-3-butene-2-ol, 8-PN, 8-prenylnaringenin, beer, Cannabaceae (family), colupulone, common hops, European hops, hop, hop strobile, Hopfen (German), houblon (French), humulon, humulus, Humulus lupulus, iso-alpha-acids, lupulin, lupulus, Lupuli strobulus, prenylated 2´-hydroxychalcones, prenylflavonoids, spent hops, xanthohumol, Ze 91019.
- The hop is a member of the Cannabaceae family, traditionally used for relaxation, sedation, and to treat insomnia. A number of methodologically weak human trials have investigated hops in combination with valerian (Valeriana officinalis) for the treatment of sleep disturbances, and several animal studies have examined the sedative properties of hops alone. However, the results of these studies are equivocal, and there is currently insufficient evidence to recommend hops alone or in combination for any medical condition.
- Hops are also sometimes found in combination products with passionflower (Passiflora incarnata), skullcap (potentially damaging to the liver), or with a high percentage of alcohol (up to 70% grain alcohol), confounding the association between the herb and possible sedative or hypnotic effects.
- Hops contain phytoestrogens that may possess estrogen receptor agonist or antagonist properties with unclear effects on hormone-sensitive conditions, such as breast, uterine, cervical, or prostate cancer or endometriosis.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Animal studies report that hops may have sedative and sleep-enhancing (hypnotic) effects. However, little human research has evaluated the effects of hops on sleep quality. Further study is needed in this area before a strong recommendation can be made.
When used in combination with other products, hops may help alleviate menopausal symptoms, such as hot flashes and difficulty sleeping, because it has estrogen-like activity. However, until more well-designed studies are performed, a strong recommendation cannot be made.
Early clinical research suggests that a combination formula containing hops may help reduce symptoms of rheumatic diseases, such as osteoarthritis, rheumatoid arthritis, and fibromyalgia. However, well-designed human trials using hops alone are needed to determine if these positive effects are specifically the result of hops.
Hops have been used traditionally as a sedative, for relaxation and reduction of anxiety. Although some animal studies suggest possible sedative properties, there is limited human research in this area. Better studies are needed before a firm conclusion can be drawn.
*Key to grades:
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Adults (18 years and older)
- For insomnia or sleep disturbances, studies have used 300 to 400 milligrams of hops extract combined with 240 to 300 milligrams of valerian extract, taken by mouth before bed. Traditionally, doses of 0.5 to 1.0 gram of dried hops extract or 0.5 to 1.0 milliliter of liquid hops extract (1:1 in 45% alcohol) have been taken up to three times daily, although using hops alone has not been well studied.
- Intravenous/intramuscular dosing is not recommended.
Children (younger than 18 years)
- Hops extract is traditionally considered to be one of the milder sedative herbs and to be safe for children. However, there is limited research in this area and safety has not been clearly established.
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
- Rash (contact dermatitis) and difficulty breathing have been reported mainly in hops harvesters. Allergy to hops pollen has also been reported. Hops allergy has been reported in a patient with previous severe allergic reactions to peanut, chestnut, and banana. Therefore people allergic to any of these agents should avoid hops.
Side Effects and Warnings
- Dry cough, difficulty breathing, chronic bronchitis, and other occupational respiratory diseases have been associated with hops. Dust from hops can contain harmful bacteria. Long-term breathing problems have been reported.
- Hops may cause mild central nervous system (CNS) depression (drowsiness, slowed breathing and thinking), especially when taken with drugs or herbs/supplements that also cause CNS depression. Caution is advised while driving or operating machinery.
- Eating hops in large quantities may cause seizure, hyperthermia, restlessness, vomiting, stomach pain, and increased stomach acid. It is unclear what effects may occur in hormone-sensitive conditions such as cancer (breast, uterine, cervical, prostate) or endometriosis.
- Hops may lower blood sugar levels in normal individuals, but may actually increase blood sugar in those with diabetes. Caution is advised in patients 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 provider, and medication adjustments may be necessary.
Pregnancy and Breastfeeding
- Hops are not recommended during pregnancy or lactation due to possible hormonal and sedative effects. Limited research is available in these areas. Many tinctures contain high levels of alcohol and should be avoided during pregnancy.
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Interactions with Drugs
- Hops may cause mild central nervous system (CNS) depression (drowsiness, slowed breathing, and thinking) and may add to the effects of drugs that also cause CNS depression or sedation. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, and alcohol. Caution is advised while driving or operating machinery.
- Based on preliminary animal studies, hops may lower blood sugar levels in normal individuals, but may actually increase blood sugar in those with diabetes. Caution is advised when using medications that may lower blood sugar. Patients taking drugs for diabetes by mouth or patients taking insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.
- Laboratory research shows that estrogen-like substances in hops may have stimulatory or inhibitory effects on estrogen-sensitive parts of the body. It is not clear what interactions may occur when used with other hormonal therapies such as birth control pills, hormone replacement therapy, tamoxifen, or aromatase inhibitors like letrozole (Femara®).
- Hops may interfere with the way the body processes certain drugs using the liver’s “cytochrome P450” enzyme system. As a result, the levels of these drugs may be decreased in the blood and the intended effects may be reduced. Patients using any medications should check the package insert and speak with a healthcare professional or pharmacist about possible interactions.
- Taking phenothiazine anti-psychotic drugs with hops is said to possibly increase the risk of hyperthermia (increased body temperature), although there is a lack of reliable human studies in this area.
- Many tinctures contain high levels of alcohol and may cause nausea or vomiting when taken with metronidazole (Flagyl®) or disulfiram (Antabuse®).
- Hops compounds have also been shown to reduce triglycerides and free fatty acid blood levels and therefore may have additive effects with cholesterol-lowering drugs such as lovastatin (Mevacor®).
- Hops may also interact with antibiotic, antidepressant, antifungal, anti-inflammatory, and gastrointestinal drugs.
Interactions with Herbs and Dietary Supplements
- Hops may cause mild central nervous system (CNS) depression (drowsiness, slowed breathing, and thinking) and may add to the effects of herbs or supplements that also cause CNS depression or sedation. Caution is advised while driving or operating machinery.
- Based on preliminary animal studies, hops may lower blood sugar levels in normal individuals, but may actually increase blood sugar in those with diabetes. Caution is advised when using herbs or supplements that may affect blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
- Hops may interfere with the way the body processes certain drugs using the liver’s “cytochrome P450” enzyme system. As a result, the levels of other herbs or supplements may become too low in the blood. It may also alter the effects that other herbs or supplements potentially may have on the P450 system. Patients using any medications should check the package insert and speak with a healthcare professional, including a pharmacist, about possible interactions.
- Because hops contain estrogen-like chemicals, the effects of other agents believed to have estrogen-like properties may be altered.
- Hops compounds have also been shown to reduce triglycerides and free fatty acid blood levels and therefore may have additive effects with cholesterol-lowering herbs and supplements such as guggul or red yeast.
- Hops may also interact with antibacterial, antidepressant, antifungal, anti-inflammatory, antineoplastic, antioxidant, antipsychotic, and gastrointestinal supplements.
Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.
- This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration ().
- Chadwick LR, Nikolic D, Burdette JE, et al. Estrogens and congeners from spent hops (Humulus lupulus). J Nat Prod 2004 Dec;67(12):2024-32.
- Estrada JL, Gozalo F, Cecchini C, et al. Contact urticaria from hops (Humulus lupulus) in a patient with previous urticaria-angioedema from peanut, chestnut and banana. Contact Dermatitis 2002;46(2):127.
- Gerhauser C, Alt A, Heiss E, et al. Cancer chemopreventive activity of Xanthohumol, a natural product derived from hop. Mol Cancer Ther 2002;1(11):959-969.
- Henderson MC, Miranda CL, Stevens JF, et al. In vitro inhibition of human P450 enzymes by prenylated flavonoids from hops, Humulus lupulus. Xenobiotica 2000;30(3):235-251.
- Heyerick A, Vervarcke S, Depypere H, et al. A first prospective, randomized, double-blind, placebo-controlled study on the use of a standardized hop extract to alleviate menopausal discomforts. Maturitas 2006;54(2):164-75.
- Lukaczer D, Darland G, Tripp M, et al. A pilot trial evaluating Meta050, a proprietary combination of reduced iso-alpha acids, rosemary extract and oleanolic acid in patients with arthritis and fibromyalgia. Phytother Res 2005;19(10):864-9.
- Milligan S, Kalita J, Pocock V, et al. Oestrogenic activity of the hop phyto-oestrogen, 8-prenylnaringenin. Reproduction 2002;123(2):235-242.
- Morali G, Polatti F, Metelitsa EN, et al. Open, non-controlled clinical studies to assess the efficacy and safety of a medical device in form of gel topically and intravaginally used in postmenopausal women with genital atrophy. Arzneimittelforschung 2006;56(3):230-8.
- Morin CM, Koetter U, Bastien C, et al. Valerian-hops combination and diphenhydramine for treating insomnia: a randomized placebo-controlled clinical trial. Sleep 2005 Nov 1;28(11):1465-71.
- Possemiers S, Bolca S, Grootaert C, et al. The prenylflavonoid isoxanthohumol from hops (Humulus lupulus L.) is activated into the potent phytoestrogen 8-prenylnaringenin in vitro and in the human intestine. J Nutr 2006 Jul;136(7):1862-7.
- Schellenberg R, Sauer S, Abourashed EA, et al. The fixed combination of valerian and hops (Ze91019) acts via a central adenosine mechanism. Planta Med 2004 Jul;70(7):594-7.
- Spiewak R, Dutkiewicz J. Occupational airborne and hand dermatitis to hop (Humulus lupulus) with non-occupational relapses. Ann Agric Environ Med 2002;9(2):249-252.
- Stevens JF, Page JE. Xanthohumol and related prenylflavonoids from hops and beer: to your good health! Phytochemistry 2004 May;65(10):1317-30.
- Sun J. Morning/evening menopausal formula relieves menopausal symptoms: a pilot study. J Altern Complement Med 2003 Jun;9(3):403-9.
- Yajima H, Ikeshima E, Shiraki M, et al. Isohumulones, bitter acids derived from hops, activate both peroxisome proliferator-activated receptor alpha and gamma and reduce insulin resistance. J Biol Chem 2004 Aug 6;279(32):33456-62.
Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to . Selected references are listed below.