Hops (Humulus lupulus L.): Clinical Pharmacognosy, Dosing & Therapeutics

Re-Evaluating the Sedative-Bitter Standard: From Monastic Dispensaries to Modern Neuro-Cardiology & Gynaecology

Among central nervous system sedatives, aromatic bitters, and pelvic trophorestoratives, Hops—botanically designated as Humulus lupulus L. (family Cannabaceae), and known pharmaceutically as Lupuli strobilus—remains one of the most multi-systemic botanicals in clinical phytotherapy. Known across global materia medica as Pi Jiu Hua (TCM), Chmiel (Polish), Lupulus (Latin), Houblon (French), Hopfen (German), and Lúpulo (Spanish), Hops represents a profound intersection between neuro-pharmacology, gastroenterology, endocrinology, and metabolic medicine.

Hops are vigorous, climbing herbaceous perennials capable of sending twining bines up to 30 feet (9 meters) in length. Commercial cultivation trains these bines onto high trellises, where growth is triggered by the expanding photoperiod of early summer, blooming around July or August in the Northern Hemisphere. The species is dioecious—bearing distinct male (staminate) and female (pistillate) flowers on separate plants. The fragrant, wind-pollinated female inflorescences develop into pale green, papery, cone-like strobiles. Structurally, each strobile consists of overlapping membranous bracts enveloping a central axis with dry achene fruits. Concentrated at the base of these bracts are golden, sticky micro-glands that secrete lupulin—a granular resinous powder containing the plant's essential volatile oils, bitter phloroglucinol derivatives, and prenylated flavonoids.

Botanically related to Cannabis (Cannabaceae) and distantly to stinging nettles (Urticaceae), Hops yields a complex phytochemical matrix. Modern clinical research confirms its capacity to bind GABAergic, glutamate, glycine, cholecystokinin (CCK), melatonin, and endocannabinoid receptors, while simultaneously exerting potent anti-inflammatory, antimicrobial, anticarcinogenic, and phytoestrogenic activities.

---

📜 History, Folklore & Classical Herbalist Heritage

Hops carries an extensive legacy spanning classical Islamic medicine, monastic pharmacy, European folk tradition, Native American therapeutics, and Eclectic dispensary practice:

• Etymology & Roman Legend: The generic name Humulus derives from the Medieval Latin humus (rich soil) and Anglo-Saxon hoppan (to climb). The specific epithet lupulus stems from the ancient Roman observation that wild hops twined aggressively around willow trees "like wolves among sheep" (lupus salictarius).
• Classical Islamic & Monastic Writings: Mentioned in classical Islamic literature by Avicenna (Ibn Sina, 980–1037 AD) in Al-Qanun fi'l-tibb and praised by Ibn Al-Baitar (1188–1248 AD) for its digestive and calming properties. In 1079 AD, Abbess Hildegard von Bingen wrote in Physica that while Hops bitterness "fends off decomposition of beverages and increases shelf life," its heavy intake "causes melancholy to increase, gives a sad mind, and makes the intestines heavy." Monastic herbalists prized Hops in brewing specifically to preserve beer while dampening libido and excess sexual excitability among monks (giving rise to its reputation as an anaphrodisiac).
• Royal & Eclectic Dispensary Lore: King George III (1738–1820), famed for severe nervous agitation and insomnia, regularly utilized Hop pillows to calm his central nervous system. Native American, European, and Eclectic herbalists deployed hot Hop fomentations (muslin bags dipped in hot water) over the face to soothe acute facial neuralgia, earaches, and toothaches, or washed the scalp with beer to stimulate hair growth.
• Ayurvedic & Eastern Applications: In Ayurvedic medicine, Hops was indicated for restlessness associated with nervous tension, headaches, indigestion, priapism, and sexual neurosis—corroborating Western findings on its anaphrodisiac and spasmolytic qualities.
• Maud Grieve (A Modern Herbal, 1931): Grieve highlighted Hops as an exceptional anodyne, nervine, and digestive vehicle, writing: "Hops have tonic, nervine, diuretic and anodyne properties... Both preparations were formerly much given in nervousness and at bedtime to induce sleep... A pillow of warm Hops will often relieve toothache and earache and allay nervous irritation."
• Harvey Felter & King's American Dispensatory: Eclectic physicians prized Hops for fermentative dyspepsia linked to emotional brooding, noting: "A 'hop-pillow' is a favorite device for procuring sleep... A hot 'hop bag' applied to the face is a favorite domestic cure for neuralgic face ache."

---

🔬 Phytochemistry & Receptor Pharmacology

The therapeutic efficacy of Humulus lupulus relies upon a dense concentration of secondary metabolites housed within the yellow lupulin glands:

1. Resinous Bitter Phloroglucinol Derivatives (15–20%):
   • Alpha-Acids (Humulones): Comprising humulone, cohumulone, and adhumulone. Highly potent in vivo sedatives that exert strong anti-inflammatory, antibacterial, and metabolic-modulating properties.
   • Beta-Acids (Lupulones): Comprising lupulone, colupulone, and adlupulone. Demonstrate powerful antibacterial activity against Gram-positive bacteria and human pathogens.
   • Iso-Alpha-Acids & Matured Resin Acids: Produced during brewing or storage; regulate glucose tolerance, lipid oxidation, and joint inflammation.
2. Volatile Essential Oils & Organoleptic Quality (0.3–1.0%):
   • Rich in monoterpenes and sesquiterpenes, predominantly myrcene, alpha-humulene, beta-caryophyllene, and linalool.
   • The Soporific Degradation Product (2-methyl-3-butene-2-ol): As dried Hops cure, oxidative breakdown converts volatile bitter acids into 2-methyl-3-butene-2-ol (dimethylvinyl carbinol). This volatile aliphatic alcohol acts directly on central nervous system pathways to induce potent sleep—explaining why properly stored dried hop pillows exert remarkable sleep-inducing effects!
   • Organoleptic Quality & Storage Physics: Properly stored Hops retain vibrant greenish-yellow bracts, sticky golden lupulin glands, and a fresh, resinous aroma. If stored improperly under excessive heat or dampness, alpha-acids undergo heavy breakdown into isovaleric acid, creating an unpleasant cheesy smell and potential gastric irritation. Always verify your raw material organoleptically prior to extraction.
3. Flavonoids, Chalcones & Phytoestrogens:
   • Contains Xanthohumol (a potent prenylated chalcone), Isoxanthohumol, 6-prenylnaringenin, and 8-prenylnaringenin (8-PN).
   • 8-Prenylnaringenin (8-PN): Recognized in clinical pharmacognosy as one of the most potent plant-derived phytoestrogens known. It displays selective preference for estrogen receptor-alpha (ER-alpha) and ER-beta, decreasing luteinizing hormone (LH) levels, reducing menopausal hot flushes, and increasing bone mineral density.

Broad-Spectrum Central Nervous & Visceral Receptor Affinity

Modern neuro-pharmacological assays confirm that crude Hops extracts bind to an exceptionally broad array of human central and autonomic receptors:

• GABA (GABA-A & GABA-B) Receptors: Primary driver of central hypnotic and anxiolytic activity.
• Glutamate Receptors (AMPA, NMDA, Kainate): Modulates excitatory neurotransmission, dampening neuro-cardiac and mental excitability.
• Glycine & Chloride Channel Receptors: Reinforces spinal cord and central motor relaxation.
• Cholecystokinin (CCK-A & CCK-B) Receptors: Direct binding to CCK receptors decreases smooth muscle gut motility, relieving spastic colitis, IBS, and visceral pain.
• Melatonin Receptors: Activates central circadian clock pathways, regulating sleep latency and sleep architecture.
• Endocannabinoid (CB2) Receptors: Beta-caryophyllene content binds endocannabinoid receptors, contributing to peripheral pain relief and gut motility regulation.

---

🌿 Key Health Benefits & Pharmacological Actions of Hops

In Western clinical pharmacognosy and botanical dispensary practice, Humulus lupulus exhibits twelve primary actions:

1. Strong Sedative & Hypnotic: Binds GABA, melatonin, and glycine receptors to decrease sleep latency and enhance slow-wave sleep.
2. Nervine Relaxant & Anxiolytic: Reduces central nervous excitability, mental restlessness, and stress-induced cardiac agitation.
3. Aromatic Bitter & Orexigenic: Stimulates gustatory bitter receptors, boosting saliva, gastric acid, and bile output to stimulate sluggish appetite.
4. Visceral Antispasmodic (Spasmolytic): Binds CCK receptors to relax smooth muscle contractions across the stomach, intestines, uterus, and bladder.
5. Anaphrodisiac: Dampens excessive sexual excitability, satyriasis, nymphomania, priapism, and nocturnal emissions.
6. Phytoestrogenic: 8-prenylnaringenin binds ER-alpha and ER-beta to relieve menopausal hot flushes, night sweats, and vaginal dryness.
7. Analgesic & Anodyne: Relieves neuralgic pain, facial tic, tension headaches, earaches, toothaches, and visceral colic.
8. Anti-Inflammatory (COX-2 & Iso-Alpha-Acid Inhibitor): Inhibits inflammatory cascades, relieving osteoarthritic joint pain and systemic inflammation.
9. Antimicrobial & Antiviral: Lupulones and xanthohumol inhibit H. pylori, M. tuberculosis, C. acnes, C. diff, HSV-1/2, and HIV-1.
10. Anticarcinogenic & Chemopreventive: Xanthohumol protects DNA against mutagenic damage, inhibits angiogenesis, and induces apoptosis in cancer cell lines.
11. Metabolic & Hepatoprotective: Reduces serum triglycerides, oxidized LDL, fasting blood glucose, and protects hepatic parenchyma.
12. Soothing Diuretic & Lithotriptic: Flushes urinary gravel, reduces bladder scalding, and clears metabolic toxicosis.

---

📊 Human Clinical Trial Evidence & Evidence-Based Research

Clinical trial literature validates Hops' therapeutic actions across neurology, gynaecology, oncology, metabolic disease, and gastroenterology:

1. Sleep Architecture, EEG Dynamics & Caffeine Antagonism

• Benzodiazepine-Equivalent Efficacy: Clinical trials evaluating Hops in combination with Valerian (Valeriana officinalis) demonstrated reductions in sleep latency and wake time, with significant increases in slow-wave sleep and REM sleep. EEG recordings confirmed sleep architecture improvements comparable to pharmaceutical benzodiazepines (such as Lexotanil / Bromazepam), but with zero daytime cognitive impairment or vigilance loss.
• Single-Dose vs. Chronic Administration: Single-dose clinical electrohypnogram trials showed immediate improvements in sleep quantity. However, optimal clinical resolution of chronic insomnia develops after 28 days of continuous use, indicating both immediate sedative and long-term circadian rhythm modulating mechanisms.
• Caffeine Antagonism: Oral administration of Hops 60 minutes after caffeine intake significantly suppressed caffeine-induced central nervous stimulation.
• Balneotherapy (Hop Baths): Clinical trials demonstrated that hop baths taken on three successive days produced statistically significant improvements in both objective and subjective sleep quality.

2. Gynaecology, Menopause & Osteoporosis

• Vasomotor Symptom Relief: Clinical trials in menopausal women confirm that standardized Hops extracts (rich in 8-PN) produce rapid decreases in Kupperman Index scores, visual analogue scales, and Menopause Rating Scale values—significantly reducing hot flushes, night sweats, palpitations, insomnia, sweating, and irritability.
• Vaginal Atrophy & Dryness: An open-label clinical trial evaluating a topical vaginal gel containing Hops extract, hyaluronic acid, liposomes, and Vitamin E demonstrated marked clinical reversal of vaginal dryness, burning, itching, dyspareunia, and mucosal inflammation.
• Bone Mineral Density (BMD): Hops constituents display estradiol-like effects on osteogenic differentiation in vitro and in vivo. A cross-sectional epidemiological study of 1,697 healthy women (mean age 48.4 years) revealed significantly higher bone mineral density among women beer drinkers due to dietary prenylflavonoid intake.

3. Breast Cancer Safety Profile & Oestrogen Metabolism

• Non-Toxic Oestrogen Pathway Induction: Concerns regarding phytoestrogens in estrogen-receptor positive (ER+) breast cancer have been addressed in modern pharmacognosy. Hops compounds—specifically 6-prenylnaringenin—preferentially induce the non-toxic oestrogen 2-hydroxylation pathway in human breast cell lines. This modulates oestrogen metabolism toward protective pathways, inhibiting cancer cell proliferation and inducing apoptosis.
• Aromatase & Uterine Safety: In vivo models demonstrate that Hops extracts do not exert hypertrophic oestrogenic effects on uterine tissue. Furthermore, xanthohumol and flavonoid chalcones inhibit aromatase enzymes, decreasing endogenous oestrogen synthesis in aberrant tissues.

4. Antimicrobial, Antiviral & Antiparasitic Spectrum

• Helicobacter pylori Inhibition: In vivo studies confirm that Hops extracts strongly inhibit H. pylori strains isolated from patients with chronic gastritis, serving as an effective adjunct or alternative to antibiotics.
• Tuberculosis (Mycobacterium tuberculosis): Historical observations of lower TB rates among brewery workers led to in vitro testing, confirming that Hops ethanolic extracts (4 and 8 mg/mL) exert marked inhibitory activity against both rifampicin-sensitive and multi-drug resistant M. tuberculosis isolates.
• Anaerobic Bacteria & Nosocomial Diarrhoea: Xanthohumol and lupulones demonstrate strong antibacterial activity against anaerobic pathogens, including Clostridium difficile.
• Dermatological Acne & Anticollagenase Action: Xanthohumol, humulones, and lupulones show strong inhibition of Cutibacterium acnes alongside moderate-to-strong inhibition of human anticollagenase enzymes, preventing dermal tissue breakdown.
• Antiviral & Antimalarial Activity: Demonstrates active inhibition against Herpes Simplex Virus Type 1 and 2 (HSV-1, HSV-2), Human Immunodeficiency Virus 1 (HIV-1), Cytomegalovirus (CMV), Bovine Viral Diarrhoea Virus, and inhibits replication of Plasmodium falciparum (malaria).

5. Metabolic, Rheumatoid & Hepatoprotective Actions

• Osteoarthritis WOMAC Reduction: In a 6-week open-label clinical trial of patients suffering from knee osteoarthritis, oral administration of 1,000 mg/day of iso-alpha-acids produced a 54% reduction in total WOMAC Global scores.
• Type 2 Diabetes & Obesity: Isohumulones and xanthohumol improve lipid metabolism, glucose tolerance, and insulin sensitivity. Clinical subjects treated with isohumulones demonstrated reduced plasma glucose, triglycerides, and free fatty acids comparable to pharmaceutical antidiabetic agents, alongside increased liver fatty acid oxidation, hypertrophic adipocyte apoptosis, and reduced systolic blood pressure.
• Cardiovascular Risk (Elderly Nun Cohort Study): Clinical trial data evaluating elderly nuns living in a controlled lifestyle showed that daily intake of non-alcoholic beer or commercial Hops extract (400 mg/day) produced statistically significant reductions in serum total cholesterol (p < 0.005), triglycerides (p < 0.005), oxidized LDL antibodies (p < 0.05), C-reactive protein (CRP), and Interleukin-6 (IL-6), while increasing reduced glutathione (GSH) and alpha-tocopherol.
• Hepatoprotection & NAFLD: Xanthohumol inhibits multiple cellular steps in chronic liver disease progression, offering clinical protection against Non-Alcoholic Fatty Liver Disease (NAFLD).

---

☯️ Traditional Eastern & Western Energetics

Nature, Taste & Qualities (The Dual Polarized Nature)

As detailed by Peter Holmes, Hops possesses a unique polarized energetic architecture combining two distinct taste profiles:

• The Bitter Taste Profile (Cooling & Downward-Moving): Like Gentian root, the bitter resins act as a cold, downward-moving digestive stimulant and cholagogue. It addresses upper-gastric stagnation, gallbladder Qi stasis, loss of appetite, fatigue, and clears Damp-Heat from the skin and urinary bladder.
• The Pungent Taste Profile (Relaxing & Sophorific): Like Lavender flower, the pungent, aromatic volatile oils (high in sesquiterpenes) act as a general nervous relaxant and sedative. It calms constrained Qi, relieves visceral spasms, and clears hot-type insomnia.
• Tropism & Meridians: Central Nervous System, Stomach, Liver, Heart, Urinary & Reproductive Organs; Kidney, Heart, Liver, and Pericardium Meridians.
• Constitutional Ground: Sanguine and Choleric krases. Highly indicated for overheated, tense, hyper-reactive biotypes presenting with visceral spasm, hypertension, and emotional agitation.

Traditional Pattern Classification & Clinical Indications

• Clears Damp-Heat & Reduces Infection: Clears skin damp-heat (oozing eruptions, acne, eczema, ringworm, scrofula), bladder damp-heat (scalding dysuria, acute cystitis, urinary stones), and lung TB. Actively clears shao yang and shao yin stage fevers with low-grade empty heat (acting like Wormwood or Qing Hao).
• Relaxes Constraint & Harmonizes Intestinal Qi: Resolves neurogenic colitis, IBS, abdominal pain, acid reflux, fermentative dyspepsia, and epigastric bloating that worsens under emotional stress or anxiety.
• Drains Kidney Fire, Sinks Floating Yang & Calms the Shen (Mind): Addresses insomnia, night sweats, hot flushes, sexual overstimulation, premature ejaculation, wet dreams, dizziness, and restlessness arising from Kidney and Heart Yin deficiency. In traditional energetic acupuncture frameworks, Hops replaces the Chinese botanical Zhi Mu (Anemarrhena), mirroring the acupuncture point combination of PC-8, HT-6, HT-8, KI-3, KI-6, and BL-15.
• Unbinds Uterus Qi & Regulates Menstruation: Soothes spasmodic dysmenorrhea, stress-induced uterine cramps, and scanty menstrual flow.

---

💡 Reflexive Extraction Physics & Pharmacy SOPs

CRITICAL PHARMACY RULE: THE 60% ABV RESIN REQUIREMENT & ORGANOLEPTIC VERIFICATION
1. Solubility Physics: The therapeutic alpha/beta acids (humulones/lupulones) and essential oils of Hops are lipophilic and poorly soluble in water or low-alcohol menstruums. A minimum ethanol concentration of 60% ABV is mandatory for hydroethanolic extracts to solubilize and stabilize these golden lupulin resins.
2. Organoleptic Quality SOP: Hops strobiles must be organoleptically verified before extraction. Ensure the strobiles retain vibrant greenish-yellow bracts and sticky, golden lupulin glands with a clean, resinous aroma. Avoid improperly stored or damp material that has turned brown or developed a sharp, cheesy odor from excessive isovaleric acid accumulation.

1. Steeped Covered Infusions: When preparing hot teas, Hops must be steeped in a tightly closed vessel for 15 to 30 minutes to prevent the escape of volatile hypnotic mono- and sesquiterpenes.
2. The Physics of the Hop Pillow: Inhaling volatile 2-methyl-3-butene-2-ol vapors released by gentle body heat bypasses hepatic first-pass metabolism, delivering direct sedative signals across the olfactory bulb to the central nervous system.

---

🍯 The Apothecary Recipe Corner: Clinical Formulations

Recipe 1: The Practitioner’s Hop Pillow (for Insomnia & Facial Neuralgia)

Inspired by Harvey Felter, Maud Grieve, King George III, and T.J. Lyle—a classic physical formulation for sleep latency, nervous tension headaches, and facial neuralgia.

• Ingredients & Materials:
  • 100 g Dried Organic Hop Cones (Humulus lupulus — organoleptically verified)
  • 50 g Dried Lavender Flowers (Lavandula angustifolia)
  • 50 g Dried Chamomile Flowers (Matricaria chamomilla)
  • Small unbleached cotton or linen pillow pouch (approx. 20x20 cm)
• Method:
  1. Gently crush the dried Hop cones in your hands to rupture the lupulin glands and release the yellow aromatic resins.
  2. Mix thoroughly with the Lavender and Chamomile flowers in a large bowl.
  3. Stuff the aromatic blend tightly into the cotton pouch and sew or tie the end securely.
  4. Place inside or directly beside your standard sleeping pillow. Warm gently over a clean radiator prior to sleep to intensify volatile vapor release.

Recipe 2: Nighttime Neuro-Digestive Infusion

A bitter-relaxing tea designed to calm emotional brooding, ease fermentative dyspepsia, and induce deep sleep.

• Ingredients:
  • 1.5 g Dried Hop Cones
  • 2.0 g Dried Valerian Root (Valeriana officinalis)
  • 2.0 g Dried Lemon Balm Leaves (Melissa officinalis)
  • 300 mL Boiling Filtered Water
• Method:
  1. Place herbs into a teapot or French press.
  2. Pour boiling water over the herbs, cover tightly with a lid, and steep for 20 minutes.
  3. Strain through fine muslin. Drink 45 minutes before bedtime.

Recipe 3: Hot Hop Anodyne Fomentation / Poultice

A traditional Eclectic remedy for localized neuralgic face pain, earaches, toothaches, and inflamed rheumatic joints.

• Method: Place 30 g of whole dried Hops in a muslin bag. Immerse in boiling water for 3 to 5 minutes until thoroughly heated and saturated. Squeeze gently to remove excess liquid. Apply the warm hop bag directly over the painful facial area or joint for 20 minutes.

---

📋 Comprehensive Prescribing Information & Dosing

Preparation Format	Ratio / Menstruum	Single Dose	Daily Total Range	Weekly Total Range
Concentrated Fluid Extract (Brice-Ytsma SOP)	1:2 (60% Ethanol)	0.5 – 1.0 mL	1.5 – 3.0 mL / day	10.0 – 20.0 mL / week
Concentrated UK Tincture	1:3 (60% Ethanol)	0.5 – 3.0 mL	1.5 – 9.0 mL / day	10.5 – 63.0 mL / week
Standard Tincture (BHP Standard)	1:5 (60% Ethanol)	1.5 – 4.0 mL	4.5 – 12.0 mL / day	31.5 – 84.0 mL / week
Crude Infusion (Tea)	Dried Strobile in Water	0.5 – 2.0 g	1.5 – 6.0 g / day	10.5 – 42.0 g / week
Iso-Alpha-Acids (Osteoarthritis Trial)	Purified p-iso-alpha-acids	500 mg	1,000 mg / day	7,000 mg / week

Clinical Dosing & Formulation Rules

• The "Anergic vs. Anxious Depression" Rule: Medical herbalists emphasize that Hops is contraindicated in anergic depression—states of flat, low-energy depression characterized by weakness, lethargy, or fatigue—as its heavy, sinking energetic nature can deepen mental sluggishness. Conversely, for depression accompanied by high anxiety, racing thoughts, and severe restlessness, Hops is exceptionally beneficial.
• Avoid Long-Term Monotherapy: Hops is a medium-strength botanical. For extended clinical protocols, Hops should **never be used on its own**; combine it with complementary nervines or tonics (e.g., Valerian, Passionflower, Lemon Balm) to prevent energetic over-cooling.
• High Doses are Short-Term Only: Top-tier dosage ranges (e.g., 3 mL of 1:3 tincture or 4 mL of 1:5 tincture) should be used temporarily for acute insomnia or severe pain crises.

---

⚠️ Safety, Contraindications & Pharmacokinetics

• Toxicity & Safety: Hops carries a Generally Recognized as Safe (GRAS) status and exhibits low acute toxicity. It is safe for therapeutic use across adult and geriatric populations.
• Contraindications: Contraindicated in flat, anergic depression (low energy, weakness, lethargy). Due to activation of ER-alpha receptors, high-dose concentrated extracts should be used cautiously over the long term in women with oestrogen receptor-positive (ER+) breast cancer, though standard dietary and moderate therapeutic doses show protective oestrogen metabolism modulation.
• Drug Interactions: Hops potentiates prescription central nervous system depressants, sedatives, hypnotics (e.g., benzodiazepines), and alcohol. Concomitant use with pharmaceutical sedatives may require dosage adjustment.
• Side Effects: Exceptional safety profile at recommended dosages. In rare, hyper-sensitive individuals, handling fresh hop dust may trigger transient contact allergic dermatitis.

---

📚 Scholarly References & Academic Sourcing

1. Brice-Ytsma H (2020). Herbal Medicine in Treating Gynaecological Conditions (Vol. 1). Key Herbs Containing Isoflavones and Flavonoids: Hops (Humulus lupulus), pp. 99–107.
2. Holmes P (2020). The Energetics of Western Herbs: A Materia Medica Integrating Western and Chinese Therapeutics (4th ed.). Aeon Books. Hops (Humulus lupulus), p. 555.
3. Bone K (2003). A Clinical Guide to Blending Liquid Herbs: Herbal Formulations for the Individual Patient. Churchill Livingstone.
4. Whelan R (2026). Medical Herbalist Materia Medica: Hops (Humulus lupulus). rjwhelan.nz.
5. Grieve M (1931). A Modern Herbal. Dover Publications.
6. Felter HW, Lloyd JU (1898). King's American Dispensatory. Ohio Valley Company.
7. Lyle TJ (1897). Physio-Medical Therapeutics, Materia Medica and Pharmacy.
8. British Herbal Medicine Association (1998). British Herbal Pharmacopoeia (BHP). BHMA.

---