Hops

The medicinal part is the female flower cone, or strobile. Germanic peoples were using the cones as a main beer ingredient at least two thousand years ago ^{28Reference 28Swahn · 1991The Lore of Spices: Their History and Uses Around the World — [traditional reference]}. Hop pickers were observed to tire easily, and the plant gained a reputation as a sedative and sleep remedy and as a topical antibacterial. Pillows filled with hops were used for sleeplessness and nervous conditions ^{39Reference 39Committee on Herbal Medicinal Products ( · 2014Assessment report on Humulus lupulus L., flos — history of use, constituents, pharmacology and safety — [regulatory assessment]View study →}.

Hops were given for insomnia, excitability, neuralgia, headache, hysteria and delirium tremens, and also for indigestion, mucous colitis, kidney stones, gynaecological complaints and menopausal symptoms ^{31Reference 31Bone · 2003A Clinical Guide to Blending Liquid Herbs: Herbal Formulations for the Individual Patient — [traditional reference]}. In Germany, hop baths were used for gynaecological disorders ^{39Reference 39Committee on Herbal Medicinal Products ( · 2014Assessment report on Humulus lupulus L., flos — history of use, constituents, pharmacology and safety — [regulatory assessment]View study →}.

The British Herbal Pharmacopoeia classes hops as a sedative, hypnotic and topical bactericide, for neuralgia, insomnia, excitability, priapism and mucous colitis, and applied to the skin for leg ulcers ^{32Reference 32British Herbal Medicine Association · 1983British Herbal Pharmacopoeia — [traditional reference]}.

The German Commission E described hops as a sedative in 1984 ^{39Reference 39Committee on Herbal Medicinal Products ( · 2014Assessment report on Humulus lupulus L., flos — history of use, constituents, pharmacology and safety — [regulatory assessment]View study →}. The European Medicines Agency recognises hops as a traditional herbal medicine for mild symptoms of mental stress and to aid sleep ^{38Reference 38Committee on Herbal Medicinal Products ( · 2014ReviewCommunity herbal monograph on Humulus lupulus L., flos — indications, posology, contraindications, pregnancy and lactation — [regulatory monograph]View study →}.

Native Americans used hops to induce sleep and for nervousness, breast and womb problems, inflamed kidneys, bladder problems, rheumatism, intestinal pain, fever, earaches, pneumonia and coughs, and as a tonic and stimulant ^{36Reference 36Small · 1997Humulus lupulus Linnaeus — species and genus description, varieties, habitat, distribution and Native American uses — floraView study →}.

Hops carry 8-prenylnaringenin, which competes strongly with 17β-estradiol at both the α and β estrogen receptors. Related hop flavonoids have less than 1% of its estrogenic activity ^{5,6Reference 5Milligan SR et al. · 2000In vitroThe endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavonoids — [in vitro]View study →Reference 6Tronina T et al. · 2020ReviewFlavonoids as Phytoestrogenic Components of Hops and Beer — [review]View study →}.

Four randomised trials have tested hop extracts, and they conflict. In a 12-week study in 67 menopausal women, all groups improved, including placebo. An extract delivering 100 µg 8-PN a day beat placebo on the Kupperman index at 6 weeks (P=0.023) but not at 12 weeks, and a 250 µg dose was less active. Hot-flush scores fell more than on placebo with both doses at 6 weeks ^{1Reference 1Heyerick A et al. · 2006RCTA first prospective, randomized, double-blind, placebo-controlled study on the use of a standardized hop extract to alleviate menopausal discomforts — [randomized]View study →}.

In a 16-week crossover in 36 women, both groups improved over the first eight weeks, slightly more on placebo. After the switch, women moving from placebo to the extract kept improving while those moving to placebo got worse. The overall treatment effect was not significant, though time-specific estimates favoured the extract at 16 weeks ^{2Reference 2Erkkola R et al. · 2010RCTA randomized, double-blind, placebo-controlled, cross-over pilot study on the use of a standardized hop extract to alleviate menopausal discomforts — [randomized]View study →}.

In 120 women with early menopausal symptoms, hop tablets lowered the Greene score and the number of hot flushes more than placebo at 4, 8 and 12 weeks ^{3Reference 3Aghamiri V et al. · 2016RCTThe effect of Hop (Humulus lupulus L.) on early menopausal symptoms and hot flashes: A randomized placebo-controlled trial — [randomized]View study →}. A soy-and-hop extract given to 78 women lowered menopausal symptom scores by 20.6 points against 14.8 on placebo over 12 weeks ^{4Reference 4Kim HI et al. · 2021RCTEfficacy and Safety of a Standardized Soy and Hop Extract on Menopausal Symptoms: A 12-Week, Multicenter, Randomized, Double-Blind, Placebo-Controlled Clinical Trial — [randomized]View study →}.

Gap: no adequately powered, long-duration trial has resolved the conflicting results, and the effects are tied to specific standardised extracts. A tea or ordinary tincture delivers an unknown dose of 8-PN.

In essentially every sleep trial, hops are paired with valerian, so their own contribution cannot be separated. In a US multicentre trial in 184 adults with mild insomnia, two tablets of a valerian–hops extract nightly for 28 days gave modest improvements in sleep diaries. Few comparisons with placebo reached significance, and sleep recordings showed no difference between groups. Quality of life improved more than on placebo ^{8Reference 8Morin CM et al. · 2005RCTValerian-hops combination and diphenhydramine for treating insomnia: a randomized placebo-controlled clinical trial — [randomized]View study →}.

In a 2025 randomised feasibility study of the valerian–hops preparation Ze 91019 in 40 people with occasional insomnia, fitness-tracker sleep time rose by about 22 minutes a night more than on placebo, in an exploratory analysis ^{9Reference 9Schicktanz N et al. · 2025RCTEffects of a Valerian-Hops Extract Combination (Ze 91019) on Sleep Duration and Daytime Cognitive and Psychological Parameters in Occasional Insomnia: A Randomized Controlled Feasibility Trial — [randomized]View study →}.

A tablet combining valerian, passionflower and hops (NSF-3) was compared with zolpidem in primary insomnia for two weeks. Both groups slept better, with no significant difference between them ^{10Reference 10Maroo N et al. · 2013RCTEfficacy and safety of a polyherbal sedative-hypnotic formulation NSF-3 in primary insomnia in comparison to zolpidem: a randomized controlled trial — [randomized]View study →}.

In quail, a hop extract at a dose close to that of non-alcoholic beer reduced night-time activity ^{11Reference 11Franco L et al. · 2012The sedative effects of hops (Humulus lupulus), a component of beer, on the activity/rest rhythm — [animal]View study →}. The sedation is attributed to 2-methyl-3-buten-2-ol, a breakdown product of the bitter acids. Fresh cones contain only traces of it, and the level rises during storage to a peak after about two years ^{39Reference 39Committee on Herbal Medicinal Products ( · 2014Assessment report on Humulus lupulus L., flos — history of use, constituents, pharmacology and safety — [regulatory assessment]View study →}.

Gap: no trial separates hops from valerian, so their own effect on sleep in people is untested.

In ovariectomised rats, 8-prenylnaringenin completely prevented bone loss while having little effect on the uterus. At bone-protective doses its stimulation of the uterus and endometrium was estimated to be about ten times lower than that of estradiol ^{14Reference 14Hümpel M et al. · 2005Tissue specificity of 8-prenylnaringenin: protection from ovariectomy induced bone loss with minimal trophic effects on the uterus — [animal]View study →}.

In bone-forming (MC3T3-E1) and bone-resorbing (RAW264.7) cell cultures, 8-PN raised markers of bone formation and suppressed osteoclast formation, acting mainly through estrogen receptor α rather than β ^{15Reference 15Luo D et al. · 2014In vitroEffects and mechanisms of 8-prenylnaringenin on osteoblast MC3T3-E1 and osteoclast-like cells RAW264.7 — [in vitro]View study →}.

In a one-year double-blind trial, 100 postmenopausal women with osteopenia took calcium and vitamin D with either an 8-PN-standardised hop extract or placebo. Total-body bone density rose 1.8% from baseline on the extract; the difference from placebo (1.0%) was not statistically significant (p=0.08), but more women on the extract gained at least 1% ^{13Reference 13Lecomte M et al. · 2023RCTEffect of a Hop Extract Standardized in 8-Prenylnaringenin on Bone Health and Gut Microbiome in Postmenopausal Women with Osteopenia: A One-Year Randomized, Double-Blind, Placebo-Controlled Trial — [randomized]View study →}.

Gap: there is a single human bone-density trial, using a standardised extract, and fracture outcomes are untested.

Hops’ anti-inflammatory reputation rests on xanthohumol, the prenylated chalcone of the lupulin glands. In cell and animal studies, xanthohumol suppresses NF-κB signalling and related inflammatory pathways ^{18,19Reference 18Girisa S et al. · 2021ReviewXanthohumol from Hop: Hope for cancer prevention and treatment — [review]View study →Reference 19Harish V et al. · 2021ReviewXanthohumol for Human Malignancies: Chemistry, Pharmacokinetics and Molecular Targets — [review]View study →}.

Every result is in vitro or in animals and uses the isolated compound. Little is known about how xanthohumol is absorbed and metabolised in people ^{21Reference 21Neumann HF et al. · 2022ReviewBioavailability and Cardiometabolic Effects of Xanthohumol: Evidence from Animal and Human Studies — [review]View study →}.

A separate line of work studies matured hop bitter acids (MHBAs), bitter compounds formed in aged hops, for brain function through the vagus nerve. In a randomised, double-blind trial in 60 adults aged 45–64 with self-perceived cognitive decline, 35 mg a day for 12 weeks improved verbal fluency at 6 weeks and Stroop test scores at 12 weeks compared with placebo. Fatigue and anxiety also improved ^{16Reference 16Fukuda T et al. · 2020RCTEffects of Hop Bitter Acids, Bitter Components in Beer, on Cognition in Healthy Adults: A Randomized Controlled Trial — [randomized]View study →}.

A second trial in 100 adults aged 45–69 with subjective cognitive decline found better divided attention (Symbol Digit Modalities Test) at 12 weeks, lower β-endorphin, and higher blood transthyretin. Memory retrieval improved in one subgroup ^{17Reference 17Fukuda T et al. · 2020RCTSupplementation with Matured Hop Bitter Acids Improves Cognitive Performance and Mood State in Healthy Older Adults with Subjective Cognitive Decline — [randomized]View study →}.

Effects are modest and partly subgroup-driven.

Gap: both trials use a specific matured-bitter-acid preparation, not the whole flower, and both come from the same research group.

In mice fed a high-fat diet as a model of type 2 diabetes, xanthohumol or 8-prenylnaringenin in drinking water for 20 weeks prevented weight gain, lowered blood glucose, triglycerides and cholesterol, and improved insulin sensitivity ^{20Reference 20Costa R et al. · 2017AnimalXanthohumol and 8-prenylnaringenin ameliorate diabetic-related metabolic dysfunctions in mice — [animal]View study →}.

Reviews of the animal and cell work report benefits for body weight, lipids, glucose handling and inflammation, but the animal results are inconsistent ^{21,22Reference 21Neumann HF et al. · 2022ReviewBioavailability and Cardiometabolic Effects of Xanthohumol: Evidence from Animal and Human Studies — [review]View study →Reference 22Gómez-Zorita S et al. · 2024In vitroBeneficial Effects of Xanthohumol on Metabolic Syndrome: Evidence from In Vitro and Animal Model Studies — [review]View study →}. Human studies so far cover xanthohumol’s pharmacokinetics and safety, and it was well tolerated ^{21Reference 21Neumann HF et al. · 2022ReviewBioavailability and Cardiometabolic Effects of Xanthohumol: Evidence from Animal and Human Studies — [review]View study →}.

Gap: there are no human outcome trials, and the work uses isolated compounds ^{21,22Reference 21Neumann HF et al. · 2022ReviewBioavailability and Cardiometabolic Effects of Xanthohumol: Evidence from Animal and Human Studies — [review]View study →Reference 22Gómez-Zorita S et al. · 2024In vitroBeneficial Effects of Xanthohumol on Metabolic Syndrome: Evidence from In Vitro and Animal Model Studies — [review]View study →}.

In a randomised, placebo-controlled, double-blind crossover pilot, 36 young adults (average age 25) with at least mild symptoms took a hop dry extract (two 0.2 g capsules daily) or placebo for two 4-week periods. Anxiety, depression and stress scores on the DASS-21 fell more on hops than on placebo, while morning cortisol did not change ^{12Reference 12Kyrou I et al. · 2017RCTEffects of a hops (Humulus lupulus L.) dry extract supplement on self-reported depression, anxiety and stress levels in apparently healthy young adults: a randomized, placebo-controlled, double-blind, crossover pilot study — [randomized]View study →}.

Gap: this is one small, short study in volunteers without a diagnosis, with no dose-finding and no active comparator.

Xanthohumol has a large cell and animal literature showing antiproliferative and pro-apoptotic effects across many tumour types, through pathways including Akt, AMPK, ERK, NF-κB and STAT3 ^{18,19Reference 18Girisa S et al. · 2021ReviewXanthohumol from Hop: Hope for cancer prevention and treatment — [review]View study →Reference 19Harish V et al. · 2021ReviewXanthohumol for Human Malignancies: Chemistry, Pharmacokinetics and Molecular Targets — [review]View study →}.

Gap: there is no human efficacy data, and the work uses isolated xanthohumol.

Purified humulone, lupulone and xanthohumol inhibit gut anaerobes including Clostridium difficile, C. perfringens and Bacteroides fragilis. Xanthohumol was strongest, with minimum inhibitory concentrations of 15–107 µg/mL, followed by lupulone and then humulone ^{23Reference 23Cermak P et al. · 2017In vitroStrong antimicrobial activity of xanthohumol and other derivatives from hops (Humulus lupulus L.) on gut anaerobic bacteria — [in vitro]View study →}.

Lupulone and xanthohumol also worked together with polymyxin B, tobramycin and ciprofloxacin against all Gram-positive bacteria tested and some Gram-negative ones, though not against E. coli ^{24Reference 24Natarajan P et al. · 2008In vitroPositive antibacterial co-action between hop (Humulus lupulus) constituents and selected antibiotics — [in vitro]View study →}.

All of it is in vitro. It matches the traditional use of hops as a topical antibacterial and a beer preservative.

Tolerability. The European Medicines Agency lists no known side effects and no reported overdoses. If symptoms last longer than two weeks, a doctor should be consulted ^{38Reference 38Committee on Herbal Medicinal Products ( · 2014ReviewCommunity herbal monograph on Humulus lupulus L., flos — indications, posology, contraindications, pregnancy and lactation — [regulatory monograph]View study →}.

Drowsiness. Hops may impair the ability to drive or use machines ^{38Reference 38Committee on Herbal Medicinal Products ( · 2014ReviewCommunity herbal monograph on Humulus lupulus L., flos — indications, posology, contraindications, pregnancy and lactation — [regulatory monograph]View study →}. Take care when combining them with alcohol or other sedatives.

Estrogenic activity. Hops contain 8-prenylnaringenin, one of the most potent plant estrogens known ^{5Reference 5Milligan SR et al. · 2000In vitroThe endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavonoids — [in vitro]View study →}. As a precaution, they are best set aside with an estrogen-sensitive condition (breast, uterine or ovarian cancer, endometriosis) or during hormone therapy, although this has not been formally tested.

Depression. Hops have traditionally been used with caution in depression.

Children. Use under 12 years of age is not recommended, because adequate data are lacking ^{38Reference 38Committee on Herbal Medicinal Products ( · 2014ReviewCommunity herbal monograph on Humulus lupulus L., flos — indications, posology, contraindications, pregnancy and lactation — [regulatory monograph]View study →}.

Skin reactions. Allergic reactions have been reported after contact with the herb and its oil, particularly in hop pickers. The contact dermatitis in pickers has been attributed to myrcene in the fresh oil, and the rough stem hairs can also irritate the skin ^{39,40Reference 39Committee on Herbal Medicinal Products ( · 2014Assessment report on Humulus lupulus L., flos — history of use, constituents, pharmacology and safety — [regulatory assessment]View study →Reference 40NC State Extension · 2026Humulus lupulus (common hop) — habit, flowering and plant problems — species profileView study →}.

Drug interactions. In 16 peri- and postmenopausal women taking a standardised hop extract twice daily for two weeks, the clearance of probe drugs for CYP2C9, CYP1A2, CYP2D6 and CYP3A4/5 did not change in a clinically relevant way. Alprazolam exposure fell by about 7.6%, suggesting slight CYP3A4/5 induction ^{25Reference 25van Breemen RB et al. · 2020Clinical trialPharmacokinetic Interactions of a Hop Dietary Supplement with Drug Metabolism in Perimenopausal and Postmenopausal Women — [clinical trial]View study →}. The EU monograph lists no reported interactions ^{38Reference 38Committee on Herbal Medicinal Products ( · 2014ReviewCommunity herbal monograph on Humulus lupulus L., flos — indications, posology, contraindications, pregnancy and lactation — [regulatory monograph]View study →}.