Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain hops. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with their pharmacist or health care provider before starting.

Scientists have studied hops for the following health problems:

Insomnia, poor sleep quality

Hops cause sedation and sleepiness in animals. Most studies in humans have tested the effects of hops on sleep quality when used in combination with valerian (Valeriana officinalis). Although this research does suggest effectiveness, most studies have been low quality. In addition, the effects of hops cannot be separated from the possible benefits of valerian (shown in several studies to improve sleep quality). Therefore, it remains unclear if hops are effective as a sleep aid, and further study is needed before a strong recommendation can be made.

Sedation

Hops have been traditionally used as a sedative. Early evidence from animal studies suggests possible sedative effects, although data in humans are lacking. At this time, there is not enough information to recommend hops for sedation.

Hops have been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially serious and even life-threatening. You should consult a health care provider before using hops for any unproven use.

Antibacterial Anti-inflammatory Antimycobacterial Antispasmodic Antiviral (anti-HCV, anti-Rhino, anti-herpesvirus) Anxiety Aphrodisiac Appetite stimulant Asbestosis Atherosclerosis Atopic dermatitis Breast enhancer Cancer (breast, uterine, cervical, prostate) Crohn's disease Depression Diabetes Digestion aid Dysentery Epstein-Barr virus Estrogen-like effects

Heartburn Hot flashes Irritable bowel syndrome Kidney disorders Leprosy Leukemia Lipid metabolism Menopausal symptoms Mood disturbances Muscle spasm Nervous disorders Obesity Osteoporosis Pain Parasites or worms Restlessness Rheumatic disorders Silicosis Skin ulcers — used topically Tuberculosis

An itchy rash from hops has been reported, particularly in hops harvesters. Allergy to the pollen has also been reported. Breathing difficulties have been observed rarely among hops packagers. Hops allergy has been reported in a patient with previous severe allergic reactions from peanut, chestnut and banana. Therefore, people allergic to any of these agents should avoid hops.

Based on traditional use and available studies, there have been no serious side effects reported from hops. Drowsiness or sedation may occur. Use caution if you are driving or operating heavy machinery. In animal studies, hops have increased stomach acid. There is no available research in humans in this area. Breathing difficulties have been reported in brewery workers exposed to dust from hops, barley and brewery yeast.

Chemicals in hops that are similar to the hormone estrogen may affect hormone levels, with unknown effects on conditions such as breast, uterine, cervical or prostate cancer or endometriosis. Based on animal studies, hops may increase blood sugar levels in diabetic patients (but may lower blood sugar levels in nondiabetic patients). The effects of hops on blood sugar levels are unclear; if you are taking drugs for diabetes, dosing adjustments may be necessary.

Dry cough, difficulty breathing, chronic bronchitis and other occupational respiratory diseases have been associated with hops. Dust from hops can contain harmful bacteria.

Caution should be taken during pregnancy and breast-feeding because of possible hormonal (estrogen-like) and sedative effects of hops. There is limited safety information in these areas. Be aware that some hops preparations contain high levels of alcohol and should be avoided during pregnancy.

Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with your health care provider or pharmacist before using herbs or dietary supplements.

Hops may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines, such as lorazepam (Ativan); barbiturates, such as phenobarbital; narcotics, such as codeine; and alcohol. Hops may alter the effects of birth control pills, hormone replacement therapy such as Premarin, tamoxifen and raloxifene. Hops may interfere with the way the liver breaks down certain drugs. As a result, hops may decrease the levels of these drugs. If you take any prescription drugs, ask your health care provider or pharmacist for advice before you take hops.

Based on animal studies, hops may affect blood sugar levels. Caution is advised if you are also taking prescription drugs that may lower blood sugar levels. Patients taking oral drugs for diabetes or using insulin should be monitored closely by their health care provider while using hops. Dosing adjustments may be necessary. In theory, taking hops with phenothiazines such as chlorpromazine (Thorazine) may increase the risk of some side effects, although there are no supporting data in humans. Be aware that many hops preparations contain high levels of alcohol and may cause vomiting when taken with metronidazole (Flagyl) or disulfiram (Antabuse).

Hops compounds have also been shown to reduce triglycerides and free fatty acid levels and therefore may have additive effects with cholesterol-lowering medications such as lovastatin or atorvastatin.

Hops may possess mild sedative activities when used alone and may increase sedation caused by some herbs and supplements. Hops are often found in products in combination with other herbs such as valerian (Valeriana officinalis) or passionflower (Passiflora incarnata) to increase sleepiness or sedative effects. Like many other herbs that contain phytoestrogens, such as red clover (Trifolium pratense), hops may affect other hormonal therapies. In theory, hops may decrease blood levels of herbs and supplements broken down in the liver, such as chasteberry (Vitex agnus-castus). Check with your health care provider before starting hops if you are taking other herbs, supplements or drugs. Based on animal studies, hops may affect blood sugar levels. People using other herbs or supplements that may alter blood sugar levels, such as bitter melon (Momordica charantia), should be monitored closely by their health care provider while using hops. Dosing adjustments may be necessary.

Hops compounds have also been shown to reduce triglycerides and free fatty acid levels and therefore may have additive effects with cholesterol-lowering herbs and supplements such as guggul or red yeast.

The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care provider before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.

Capsules: A dose is one-half to one gram of dried extract has been taken three times daily by mouth.

Extract: A dose of one-half to one milliliter of liquid extract (1:1 in 45 percent alcohol) has been taken three times daily by mouth.

In combination with valerian: A dose used in studies is 300 to 400 milligrams of hops extract combined with 240 to 300 milligrams of valerian (Valeriana officinalis) extract taken before bed.

The dosing and safety of hops have not been studied thoroughly in children, and it is recommended that you discuss doses with your child's health care provider before starting therapy.

Although hops have been suggested for many conditions, the best evidence supports the use of hops to treat insomnia, to improve sleep quality and for sedative effects. Be careful driving or operating machinery while taking hops alone or with other agents that may cause sedation. Remember that the alcohol in some hops preparations can cause vomiting when taken with disulfiram or metronidazole. Hops should not be taken while pregnant or breast-feeding because of possible sedative properties and hormonal effects. The hormonal effects of hops may interfere with birth control pills or hormonal drugs such as Premarin. Use caution if taking phenothiazines or drugs for diabetes. Contact your health care provider immediately if you experience side effects.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.

Natural Standard reviewed more than 225 articles to prepare the professional monograph from which this version was created.

Some of the more recent studies are listed below:

Last updated June 02, 2005

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