Arnica montana · PhytoNexus

01 Identity and provenance

Accepted binomial: Arnica montana
Common names: Arnica
Family (APG IV): Asteraceae
Part used: Flower
Verification tier: Tier 2 · Verified Clinical columns reviewed and a source is on record.
Reviewer note (2026 audit): Reference not supplied - claim unverified against primary literature.

02 Constituent chemistry

Chemical class	Marker compound	Synthetic analogue in use
Sesquiterpene Lactones	Helenalin Flower	Diclofenac

The analogue column is what makes the interaction reasoning tractable: where a constituent has a marketed structural counterpart, the counterpart's interaction profile is the starting hypothesis for the plant.

Looking up structures and physicochemical properties from PubChem…

03 Stated application

Reported activity: Muscle pain,
sprains, Bruises
Marketed in: Gel: Arnicare Gel
Cream: Boiron arnicare cream
Reported adverse effects: Skin irritation,
Allergic contact dermatitis

04 Interaction matrix

Source column, verbatim: Anti-coagulant anti-platelet NSAID's
Normalised onto 3 canonical drug classes below.

Curated from the reviewed source

Drug class	Severity	Mechanism type	Provenance	Expected effect
Anticoagulants (vitamin-K antagonists, DOACs) Haemostasis	3Major	PD-additive + PK-CYP2C9	curated B	INR destabilisation in either direction; ecchymosis, epistaxis, gum bleed…	why ▾
Chemistry of this pair. Alpha-methylene-gamma-lactone groups alkylate cysteine residues on NF-kB and are the principal Compositae contact allergens. Class mechanism. Coumarin-, salicylate- and coumestan-bearing botanicals add to vitamin-K-antagonist effect; several also compete for CYP2C9 and CYP3A4, raising S-warfarin exposure. Botanicals rich in vitamin K1 act in the opposite direction and blunt anticoagulation. Expected INR destabilisation in either direction; ecchymosis, epistaxis, gum bleeding, GI or intracranial haemorrhage. Management Do not start or stop the botanical without INR cover. Check INR at 3-5 days and again at 2 weeks. Document the product, batch and dose in the anticoagulation record. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “anti-coagulant” Find evidence for this pair Map this mechanism
Antiplatelet agents Haemostasis	3Major	PD-additive	curated B	Prolonged bleeding time, surgical and post-procedural bleeding, bruising,…	why ▾
Chemistry of this pair. Alpha-methylene-gamma-lactone groups alkylate cysteine residues on NF-kB and are the principal Compositae contact allergens. Class mechanism. Organosulfur compounds, gingerols, salicylates, ginkgolides and eugenol inhibit thromboxane A2 synthesis, platelet aggregation and PAF-mediated activation, duplicating the pharmacology of aspirin and P2Y12 blockers. Expected Prolonged bleeding time, surgical and post-procedural bleeding, bruising, haematuria. Management Stop the botanical 7-14 days before elective surgery or neuraxial anaesthesia. Record it on the pre-operative medicines list. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “anti-platelet” Find evidence for this pair Map this mechanism
NSAIDs Analgesia	3Major	PD-additive	curated B	Peptic ulceration, upper GI bleeding, acute kidney injury in volume-deple…	why ▾
Class mechanism. Salicylate-, coumarin- and eugenol-bearing botanicals add both antiplatelet activity and direct gastric mucosal irritation to cyclo-oxygenase inhibition; several also reduce renal prostaglandin-dependent perfusion. Expected Peptic ulceration, upper GI bleeding, acute kidney injury in volume-depleted patients. Management Avoid in ulcer history. Add gastroprotection where the combination is unavoidable, and monitor renal function in the elderly. Onset rapid Evidence B - reviewed clinical column, source pending Matched on “nsaid” Find evidence for this pair Map this mechanism

Predicted from constituent chemistry

These edges are not clinical findings. Each one is a rule inference: a constituent class in this plant is known to act on a target that the drug class also acts on. They are shown because a blank cell reads as “safe”, and for a Tier 1 entry a blank cell only means “not yet looked at”. Treat them as a literature-search agenda, not as a warning.

Drug class	Severity	Mechanism type	Provenance	Expected effect
Narrow-therapeutic-index CYP3A4 substrates Pharmacokinetic	4Contraindicated	PK-CYP3A4	predicted D	Toxic accumulation or subtherapeutic failure of the co-prescribed drug, s…	why ▾
Chemistry of this pair. Volatile terpenes are lipophilic, cross membranes readily and induce or inhibit CYP2B6 and CYP3A4 depending on the constituent. Class mechanism. Furanocoumarins, bergamottin, piperine, glabridin and berberine inhibit CYP3A4; hyperforin, andrographolide and several diterpenes induce it through PXR. Because CYP3A4 handles roughly half of marketed drugs, the affected list is broad and the direction is product-specific. Expected Toxic accumulation or subtherapeutic failure of the co-prescribed drug, sometimes fatal for antiarrhythmics, immunosuppressants and oncology agents. Management Screen the full regimen for 3A4 substrates. Where the substrate has a narrow index, avoid rather than monitor. Onset unspecified Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism
Hypersensitivity and allergy risk Immunology	2Moderate	Immunological	predicted D	Urticaria, angio-oedema, allergic contact dermatitis, anaphylaxis; cross-…	why ▾
Chemistry of this pair. Alpha-methylene-gamma-lactone groups alkylate cysteine residues on NF-kB and are the principal Compositae contact allergens. Class mechanism. Sesquiterpene lactones, urushiol-type catechols and protein allergens cause type I and type IV reactions with well-documented cross-reactivity across the Asteraceae and Apiaceae. Expected Urticaria, angio-oedema, allergic contact dermatitis, anaphylaxis; cross-reaction with related species. Management Take an allergy history by plant family, not by product name. Withhold in known Compositae sensitivity. Onset unspecified Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism
Topical antiseptics, keratolytics and irritants Dermatology	2Moderate	PD-additive local	predicted D	Contact dermatitis, chemical burn, photoirritation, unexpected systemic a…	why ▾
Chemistry of this pair. Volatile terpenes are lipophilic, cross membranes readily and induce or inhibit CYP2B6 and CYP3A4 depending on the constituent. Class mechanism. Essential-oil terpenes, capsaicinoids and phorbol-type diterpenes add to the barrier disruption caused by topical antiseptics, retinoids and keratolytics, and increase percutaneous absorption of anything applied with them. Expected Contact dermatitis, chemical burn, photoirritation, unexpected systemic absorption from broken skin. Management Patch test first. Never apply undiluted essential oils to broken or freshly shaved skin, or with occlusion. Onset rapid Evidence D - in silico rule prediction only Find evidence for this pair Map this mechanism

05 Hazard register

The audit recorded no hazard beyond the interaction profile. The controlled-vocabulary field reads not assessed, which means the assessment has not been done rather than that it came back clear.

06 Confusable material

No same-genus or shared-common-name entry in the corpus.

07 Mechanism map

Chemistry sorts to the left, pharmacology to the right. Dashed edges are predicted. Drag nodes, scroll to zoom, export at 3× for a figure.

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08 Open literature

Abstract-scoped query built from this binomial, its common names and its marker compounds, run live against Europe PMC, PubMed and OpenAlex, then ranked locally against an evidence hierarchy.

Checking openFDA spontaneous reports…

09 Isomechanistic neighbours

Species whose interaction profile overlaps this one, ranked by shared severity weight rather than by count — a shared contraindication counts for more than a shared minor signal. Practical use: these are the plants you should not stack with this one, because the mechanisms summate.

Species	Family	Shared classes	Jaccard
Ocimum tenuiflorum Tulsi	Lamiaceae	5	0.56
Zingiber officinale Ginger	Zingiberaceae	5	0.63
Thymus vulgaris Thyme	Lamiaceae	5	0.71
Origanum vulgare Oregano	Lamiaceae	5	0.71
Myristica fragrans Nutmeg	Myristicaceae	5	0.63
Cinnamomum cassia Cassia Cinnamon	Lauraceae	5	0.63

10 References and notes

No citation is on record for this entry. That is itself the finding: the audit flagged it, and it is why the entry does not carry an A evidence grade.

Curator notes

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