Magnolia Bark
MagnoliaceaeMagnolia officinalis
Also known as: Houpo, Hou Po, Houpu Magnolia
clinical_notes Clinical Summary
Magnolia officinalis bark (Hou Po) is a classical TCM herb used for over 2,000 years for anxiety, digestive stagnation, and respiratory complaints.
Its key bioactives—honokiol and magnolol—act as GABA-A positive allosteric modulators, providing anxiolytic and sedative effects without significant motor impairment.
Modern research supports anti-inflammatory, antioxidant, neuroprotective, and cortisol-modulating properties.
It is well-suited for stress-related GI complaints, anxiety-driven insomnia, and weight management via cortisol reduction, though CYP and CNS depressant interactions warrant clinical vigilance.
Pregnancy Safety
AHPA Safety Class 2b. Insufficient clinical data; avoid use during pregnancy. Traditional Chinese medicine restricts use in pregnancy.
Lactation Safety
Insufficient safety data for lactation. Caution advised; avoid unless under professional supervision.
warning Contraindications
- Pregnancy (avoid)Theoretical
- CNS depressants / sedatives / benzodiazepines (caution)Theoretical
- CYP1A2 / CYP2C substrates (caution)Theoretical
- Antiplatelet / anticoagulant therapy (caution)Theoretical
vital_signs Clinical Profile
Primary Indications
- check_circle anxiety
- check_circle insomnia
- check_circle depression
- check_circle gastrointestinal bloating
- check_circle asthma
- check_circle epigastric fullness
- check_circle constipation
- check_circle chronic stress
- check_circle cortisol dysregulation
- check_circle cognitive decline support
Therapeutic Actions
System Affinities
- check_circle nervous system
- check_circle digestive
- check_circle respiratory
- check_circle immune
- check_circle hepatic
labs Active Constituents
honokiol
magnolol
4-O-methylhonokiol
obovatol
alkaloids
sesquiterpenes
beta-eudesmol
bornyl acetate
history_edu Traditional Use
Traditional Chinese Medicine (TCM)
厚朴 (Hou Po)
Nature: warm
- Damp-turbidity obstructing the Middle Jiao
- Qi stagnation with food accumulation
- phlegm-cold obstructing the Lung
- cough and dyspnea
- epigastric and abdominal distension
- vomiting and diarrhea
- constipation
One of the oldest recorded TCM herbs, documented in the Shennong Bencao Jing (Divine Husbandman's Classic of Materia Medica, ~200 CE). Hou Po is considered to move Qi downward and transform dampness; it is a key herb for abdominal distension, fullness, and constipation. In Ban Xia Hou Po Tang it is combined with Pinellia for plum-pit Qi (globus hystericus / anxiety).
Traditional Uses Across Healing Systems
While many herbs lack controlled clinical trials, centuries of traditional practice across cultures provide valuable insight into their therapeutic applications.
Moves Qi, eliminates dampness, transforms phlegm, and calms cough and dyspnea. Key herb for abdominal bloating, fullness, nausea, and constipation due to Qi stagnation and damp accumulation.
Featured in classical formulas Ban Xia Hou Po Tang for anxiety/depression and Da Cheng Qi Tang for severe constipation
Key ingredient in Saiboku-To (柴朴湯), used for bronchial asthma, anxiety, and psychosomatic disorders. Also in Hange-Koboku-To for globus sensation (plum-pit throat).
Saiboku-To has been studied in RCTs for corticosteroid-sparing in asthma in Japan
Modern clinical use for anxiety, cortisol dysregulation, sleep disorders, and weight management (via cortisol reduction). Used as a standardized extract (magnolol/honokiol).
Marketed in combination with Phellodendron amurense (berberine) for cortisol and stress management
spa Parts Used
bark
- anxiety
- insomnia
- gastrointestinal bloating
- asthma
- depression
- cortisol dysregulation
Stem bark, root bark, and branch bark all used. Bark is scraped, steamed, rolled, and dried in TCM processing. Standardized extracts (10% honokiol + magnolol) are preferred for clinical use. Traditional decoctions prepared 3–15 g dried bark in water.
shield Safety
Contraindications — Evidence Basis
Pregnancy
AHPA Safety Class 2b: not for use during pregnancy. Teratogenic risk not established but insufficient data. Traditional avoidance recommended.
CNS depressants / sedatives / benzodiazepines
Honokiol acts as a positive allosteric modulator of GABA-A receptors, enhancing CNS depressant effects; additive sedation with benzodiazepines, alcohol, opioids, and sleep medications.
CYP1A2 / CYP2C substrates
Honokiol inhibits CYP1A2, CYP2C8, CYP2C9, and CYP2C19 in vitro; may reduce metabolism of drugs such as warfarin, phenytoin, and NSAIDs. Clinical significance not confirmed.
Antiplatelet / anticoagulant therapy
Magnolol demonstrates antiplatelet activity in animal studies; theoretical additive bleeding risk with anticoagulants and antiplatelet drugs.
Toxicity
No significant acute human toxicity reported at therapeutic doses. In vitro data suggest potential for hepatocellular effects at high concentrations.
At excessive doses: excessive sedation, ataxia, muscle relaxation. Contact dermatitis reported with topical cosmetic preparations.
Supportive care; discontinue use. For dermatitis: topical corticosteroids and antihistamines.
Adverse Effects
CYP Metabolism
Honokiol inhibits CYP1A2, CYP2C8, CYP2C9, and CYP2C19 in vitro (MSKCC data). Also inhibits UGT1A9 and downregulates P-glycoprotein. Clinical relevance in humans not confirmed. Use caution with narrow therapeutic index drugs metabolized by these enzymes.
swap_horiz Interactions
Benzodiazepines (diazepam, alprazolam, lorazepam)
Class: Benzodiazepine
Honokiol and magnolol are positive allosteric modulators at both synaptic and extra-synaptic GABA-A receptors (including δ-containing subtypes), potentiating GABA-induced currents. Combined with benzodiazepines this produces additive sedation, ataxia, muscle relaxation, and CNS depression.
Avoid combination, especially in elderly patients, drivers, and those with respiratory disease. Warn patients about excessive drowsiness, impaired coordination, and risk of falls. Consider using only one GABAergic agent at a time.
Alcohol and CNS depressants
Class: CNS depressant
Magnolol and honokiol produce central depressant effects (sedation, ataxia, muscle relaxation, loss of righting reflex in animal models) via GABA-A potentiation. Combined with alcohol, opioids, barbiturates, or Z-drugs there is risk of excessive CNS and respiratory depression.
Avoid concurrent use. Counsel patients to refrain from alcohol and to disclose magnolia supplement use to prescribers of any sedating medication. Particular caution in patients with sleep apnea or COPD.
CYP1A2 substrates (theophylline, clozapine, tizanidine, caffeine)
Class: CYP1A2 substrate
Magnolol is a potent uncompetitive inhibitor of CYP1A (IC50 ~1.6 μM; Ki 1.09-12.0 μM) in human and rat liver microsomes. In vivo, co-administration markedly increased AUC and Cmax of the CYP1A probe phenacetin. Honokiol also inhibits CYP1A (IC50 ~8.6 μM).
Avoid with narrow-therapeutic-index CYP1A2 substrates (e.g., theophylline, clozapine, tizanidine). If combination is unavoidable, monitor drug levels and for toxicity (e.g., tizanidine-induced hypotension, clozapine toxicity). Separate dosing if possible.
CYP2C9 substrates (warfarin, phenytoin, losartan, NSAIDs)
Class: CYP2C9 substrate
Magnolol competitively inhibits CYP2C activity (IC50 ~5.6 μM; Ki 10-15 μM) in human and rat liver microsomes. Honokiol inhibits CYP2C8, CYP2C9, and CYP2C19 in vitro. Inhibition may increase plasma levels of CYP2C9 substrates.
Monitor INR closely if combined with warfarin. For phenytoin, consider level monitoring. Use caution with glipizide and other narrow-index CYP2C9 substrates. Clinical magnitude is uncertain but mechanistic plausibility warrants vigilance.
Antiplatelet and anticoagulant agents
Class: Antiplatelet/Anticoagulant
Magnolol and honokiol demonstrate antiplatelet activity by inhibiting platelet aggregation and arachidonic acid-induced thromboxane formation. Combined with antiplatelets (aspirin, clopidogrel) or anticoagulants (warfarin, DOACs) this may increase bleeding risk.
Assess bleeding risk before combining. Monitor for signs of bleeding (bruising, epistaxis, hematuria, black stools). Discontinue magnolia 2 weeks before elective surgery. Avoid in patients with thrombocytopenia or clotting disorders.
P-glycoprotein substrates (digoxin, dabigatran)
Class: P-gp substrate
Honokiol downregulates P-glycoprotein (ABCB1/MDR1) expression, potentially increasing intestinal absorption and reducing efflux of P-gp substrates. Clinical significance is unclear but plasma concentrations of P-gp-dependent drugs could rise.
For narrow-therapeutic-index P-gp substrates (digoxin, dabigatran), consider baseline and follow-up level checks. Counsel patients to report signs of toxicity (digoxin: nausea, visual changes, arrhythmias; dabigatran: bleeding).
hub Combinations
Synergistic pairings can enhance therapeutic outcomes, while knowing suitable substitutes helps when specific herbs are unavailable or contraindicated.
Classical Formulas
1Phellodendron amurense
Moderate EvidenceClassic Western herbal combination marketed as Relora; Magnolia bark + Phellodendron bark combination shown in small trials to reduce cortisol, improve stress symptoms, and support weight management
Randomized controlled pilot study: Relora (Magnolia + Phellodendron) reduced anxiety and cortisol in mildly obese adults (Kalman DS et al. J Int Soc Sports Nutr. 2012;9(1):37).
Synergistic Combinations
1Passionflower
Limited EvidenceBoth are GABA-A modulators; complementary anxiolytic and sedative mechanisms; Magnolia bark provides cortisol modulation while Passionflower provides direct GABAergic sedation for insomnia
Mechanistically well-supported combination; limited direct combination clinical trials but strong pharmacological rationale.
science Studies
A honokiol-enriched Magnolia officinalis Rehder & E.H. Wilson. bark extract possesses anxiolytic-like activity with neuroprotective effect through the modulation of CB1 receptor
In VivoThis study evaluated a standardized Magnolia officinalis bark extract (MOE) enriched in honokiol for anxiolytic and neuroprotective activity in rodent behavioral models and an in vitro excitotoxicity model. In animal behavioral tests (elevated plus maze, open field), MOE produced significant anxiolytic-like activity comparable to reference anxiolytic drugs. The neuroprotective mechanism was investigated in neuronal cells exposed to excitotoxic stimulation, where MOE protected neurons from damage. Honokiol, as a cannabinoid CB1 receptor agonist and GABA-A positive allosteric modulator, was identified as the key active constituent mediating both the anxiolytic and neuroprotective effects. The authors concluded that MOE represents an effective and safe anxiolytic candidate with additional neuroprotective benefit.
Magnolol, a major bioactive constituent of the bark of Magnolia officinalis, induces sleep via the benzodiazepine site of GABA(A) receptor in mice
In VivoThis in vivo study in mice used EEG and electromyographic recording to evaluate the sleep-promoting effects of magnolol, a primary active neolignan from Magnolia officinalis bark. Magnolol administered intraperitoneally at doses of 5 and 25 mg/kg significantly shortened sleep latency and increased both non-REM (NREM) and REM sleep duration over a 3-hour period, while reducing wake-state bout durations. Immunohistochemical analysis showed that magnolol increased c-Fos expression in the ventrolateral preoptic area (the sleep-promoting center) and decreased it in the arousal-promoting tuberomammillary nucleus. The sleep effects were reversed by flumazenil, a benzodiazepine site antagonist, confirming that magnolol acts via the benzodiazepine binding site of GABA(A) receptors — the same mechanism as common sleep medications, but derived naturally from Magnolia bark.
medication Dosing
capsule
200-500 mg standardized extract (5-10% honokiol/magnolol)
BID
For sleep: take 30-60 min before bed. For anxiety: take morning and evening. Standardized to combined honokiol + magnolol content.
decoction
3-15 g dried bark
BID-TID
TCM traditional decoction preparation. Bark strips simmered 20-30 min. Used in Ban Xia Hou Po Tang for anxiety/globus.
Disclaimer: This information is largely AI-generated and reviewed by human experts at Evara Health. It is intended for educational and clinical reference purposes only and should not replace professional medical advice.
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