Mercurius corrosivus

A highly corrosive inorganic salt of mercury (HgCl₂) long known for its intense caustic, protoplasmic-poison action upon mucous membranes and the parenchyma of the kidneys. In larger doses it produces violent gastro-enteritis with burning pains, profuse salivation and stomatitis, dysenteric stools with tenesmus, nephritis with albuminuria and haematuria, and collapse states [Hughes], [Allen], [Clarke]. In homoeopathic pharmacy, the crude salt is triturated to prepare the centesimal or decimal potencies. The toxicologic picture—intense inflammation with excoriation, sloughing, and haemorrhagic discharges—explains many keynote symptoms under Rectum, Throat, and Urinary systems [Hughes], [Hering].

No full Hahnemannian proving is recorded; the pathogenesis is derived chiefly from [Toxicology] (poisonings) and extensive [Clinical] confirmations collated by Hering and Allen, with later summaries by Clarke, Boericke and Boger [Allen], [Hering], [Clarke], [Boericke], [Boger].

Mercurius corrosivus embodies the mercurial principle of instability and irritation raised to a corrosive pitch: tissues inflame swiftly, exude, slough, and bleed, and excretions burn their passage and the parts they touch. The patient lives in fear of the next act—stool or urination—knowing that the deed will not conclude the agony; rather, pain and urging persist after the act. This after-act tenesmus is the single most reliable clinical beacon, uniting rectum and bladder in a tortured duet. The throat, too, reveals the same principle: rapid early membrane with burning and exquisite tenderness, abundant salivation, and dysphagia that may invert the usual order (fluids worse than solids or the reverse) as phases shift. The psyche is a mirror to the body’s storm: anxious, irritable, hurried, yet exhausted; internal fire with external chill; a restless stillness born of dread that any motion, sip, or swallow will rekindle the knives within.

Miasmatically, the syphilitic tone is clear—destruction, haemorrhage, ulceration, and downward momentum to collapse. Yet a sycotic accent is present in the persistent spasm and exudation, the body’s attempt to wall off damage with membranes and fibrin. Kingdom signature (mineral, corrosive salt) appears in the chemistry of symptoms: metallic fetor, profuse salivation, and shreddy, blood-stained mucus, all pointing to HgCl₂’s protoplasmic toxicity [Hughes], [Allen]. Compared with Arsenicum, Merc-cor. shows less existential anxiety about death and more local dread of functional acts; compared with Merc-sol., the pace is more violent, with more blood, earlier membrane, and the hallmark post-act torture. The remedy’s polarities (external cold vs internal burning; transient comfort from warmth that never reaches the core; momentary calm after sleep before the next paroxysm) recur across systems and anchor prescribing. When the clinical scene is of small excretions with great straining, burning like fire, pains persisting after, with fetor and haemorrhage, Mercurius corrosivus stands near the front.

• Mouth & Salivary glands—acute stomatitis with profuse, offensive salivation; gums tender, ulcerating; rapid sloughing mirrors mercury’s caustic action [Hering], [Allen]. See Mouth.
• Throat & Fauces—violent, burning inflammation; early grey-white membrane; dysphagia with stabbing pains; corrosive exudation [Clarke], [Boericke]. See Throat.
• Stomach & Small Intestine—burning, cutting gastritis and enteritis; incessant nausea; smallest sip aggravates [Allen], [Hughes]. See Stomach/Abdomen.
• Colon & Rectum—the great tenesmus remedy: incessant urging with scanty, shreddy, bloody mucus; pain and urging persist after stool [Hering], [Allen]. See Rectum.
• Urinary tract & Kidneys—tenesmus vesicae with scalding, drop-by-drop urine; albuminuria, haematuria; post-dysenteric cystitis [Boger], [Clarke]. See Urinary.
• Serous membranes—acute, corrosive inflammation with plastic exudation; fibrinous deposits echo the membrane-forming throat picture [Hughes], [Clarke].
• Skin & Ulcers—burning, phagedenic tendencies; edges dark, base sloughing; exudations acrid and excoriating [Hering], [Allen]. See Skin.
• Blood & Collapse—haemorrhagic oozing, prostration, coldness with burning pains; septic states [Allen], [Clarke]. See Fever/Generalities.

Anxious, anguished restlessness with fear that the next swallow or slightest motion will provoke intolerable burning or urging; the mind is held captive by the body’s corrosive processes [Hering], [Clarke]. Irritable, snappish, the pains making him impulsive or even delirious in severe toxic states [Allen]. Great internal uneasiness with dread of stool and urine because each act renews the torture—this anticipatory anxiety is practical in case-taking [Hering]. Periods of confusion—answers slowly, mind clouded by pain and exhaustion; may drift into muttering delirium in high fever or septic collapse [Allen], [Boericke]. Oversensitive to impressions—noise, light, conversation aggravate headache and nausea [Clarke]. Suspiciousness or aversion to attendants can appear in toxic states; at other times apathetic from prostration [Hughes]. The mental picture tallies with modalities “worse at night” and with the perpetual after-act tenesmus that destroys all repose. Case: violent dysenteric tenesmus with terror of the commode; Merc-cor. 3X, frequent repetition, eased the mental dread as urging lessened [Clinical].

Little real sleep; night aggravation compels constant rising to stool or water [Hering]. Dozes between paroxysms; unrefreshing, with dreams of fire, knives, surgery—bodily pains project into dream life [Clarke]. On lying down, internal heat with surface chill; restless tossing (ties to Fever). Short naps may momentarily quiet the mind (Better after sleep—briefly), yet the next urge breaks all repose. Wakes with metallic taste and salivation.

Distressing dreams of heat, burning, blood; of failing to reach the closet; of choking while swallowing [Clarke]. Dreams often predictive of the next paroxysm—patient dreads sleep.

A corrosive, haemorrhagic, tenesmic remedy: small excretions with great straining; pains persist after the act [Hering], [Allen]. External cold with inner fire; surface relief from warmth but central burning remains (polarity). Marked prostration, yet restlessness from pain. Nightly aggravations; damp and cold weather worse. Glandular tenderness (submaxillary, mesenteric). Tendency to membranous inflammation (throat), fibrinous exudation (serous surfaces), phagedenic ulceration (skin). Resembles Ars. in burning and prostration, but has greater tenesmus and salivation; differs from Merc-sol. by the severity and post-act persistence of pain, with more blood and shreddy mucus [Clarke], [Kent], [Hering]. [Proving]/[Toxicology]/[Clinical].

Chill with external coldness and internal burning; alternations rapid; face pale then flushed; sweat cold on the brow [Boericke], [Allen]. Heat without thirst may give way to thirst for sips, each renewing gastric pain (Worse least drink). Septic states with prostration, fetor, haemorrhagic oozings; pulse small and frequent. Fever crest often at night.

Chilliness on least uncovering; heat with burning pains and anxiety; sweat cold, clammy, offensive; sweat brings scant relief—“after-act” theme even in thermic phases [Hering], [Clarke].

Frontal headache with a band-like constriction, worse from the eyes’ effort and from noise, often accompanying gastric/rectal crises [Clarke]. Vertex heat with facial pallor or flushed spots; the head throbs when the tenesmus surges [Hering]. Nausea-headache: least motion stirs both stomach and head, matching “worse motion” [Allen]. Occipital heaviness during chills; head feels too heavy to lift from the pillow. The scalp sometimes sensitive as if excoriated, a cutaneous echo of the remedy’s corrosive theme [Hughes]. In collapse states, cold sweat upon the brow with burning within—this polarity (external cold, internal fire) is characteristic [Boericke].

Conjunctival redness with burning, acrid lachrymation that excoriates the lids, a minor but consonant sign with the remedy’s caustic action [Hering]. Vision swims during paroxysms of pain; pupils variable in fever [Allen]. Photophobia present when gastric tenesmus is high; eyes feel dry and hot though tears are copious. Slight oedema of lids with soreness on touch; canthi sensitive. Not a primary eye remedy, yet the excoriating discharge theme reappears here [Clarke].

Noises aggravate cephalalgia and nausea; aural fullness during fever. Stitching pains into Eustachian region when deglutition is attempted in faucial inflammation [Clarke]. Ringing during collapse phases; hearing dulled by systemic toxemia [Allen].

Excoriating coryza, burning within the nares; mucus blood-streaked [Hering]. Smell disordered; food odours provoke nausea (ties to Stomach, “worse least food”). Sneezing jars the throat pains. The nasal mucosa’s soreness parallels mouth and throat themes [Allen].

Anxious, drawn, sometimes hippocratic; lips dry, cracked, and sore with a raw, burning feel [Clarke]. Facial alternation of pallor and flush matches vascular instability; sweat cold upon the face with internal burning [Boericke]. Submaxillary glands tender—mercurial glandular affinity [Hering].

Profuse, fetid salivation with raw, ulcerated mucosa; gingiva swollen, bleed on touch; tongue swolen, sometimes mapped, with intense burning [Hering], [Allen]. The saliva is stringy, metallic, fetid—an index of systemic corrosion. Teeth ache, loosen, sockets tender; breath offensive. The mouth mirrors the remedy’s whole nature: caustic excoriation with haemorrhage and offensive discharges [Clarke]. Warm drinks may feel momentarily soothing, reflecting Better warmth.

Gums spongy, bleed; toothache tearing, worse night and warmth of bed (mercurial group trait), yet the burning mouth often craves warmth for comfort—note the nuance [Hering]. Teeth sensitive to cold air and touch; salivation increases pain perception [Allen].

A cardinal sphere: fauces intensely red, then early grey-white membrane; tonsils and soft palate swollen; swallowing extremely painful, fluids sometimes worse than solids, or vice-versa as phases vary [Clarke], [Hering]. Sensation of rawness and burning, with stabbing to ears on deglutition. Excessive salivation dribbles, yet thirst persists; every sip renews burning—consonant with Worse least food/drink [Allen]. Submaxillary glands tender; neck externally sore to touch (ties to Worse touch). The corrosive sublimate picture contrasts with Kali-bich. (tough, stringy plugs; punched-out ulcers) and Lac-can. (alternating sides); Merc-cor. tends to earlier membrane and greater burning with salivation [Clarke], [Kent]. [Toxicology]/[Clinical].

Breathing shallow from abdominal pain; stitching to sternal region on straining [Allen]. Excoriating cough secretions; raw tracheal feeling. Not a primary chest remedy, yet the mucosal theme persists [Clarke].

Palpitations during fever and after stool from exhaustion; pulse small, frequent in collapse [Allen]. Haemorrhagic tendency may lower blood pressure with faintness on rising (ties to Generalities).

Short, hot breaths during colic; sighing in intervals. Talking aggravates throat pain and retching [Clarke].

Violent gastritis: burning from mouth to stomach; retching and vomiting of mucus, bile, sometimes blood; smallest quantity of water renews cramp [Allen], [Hughes]. A deathly nausea worsened by motion and smells, connecting to Head and Nose. Epigastrium exquisitely tender; patient holds the region and dreads swallowing. Craves warm sips (brief relief), yet “worse least food” predominates [Hering]. Sensation as if a coal burned in the stomach—an arsenical resemblance, but Merc-cor. has more tenesmus lower down and profuse salivation [Clarke], [Kent].

Cutting, burning colic, especially hypogastric, driving to stool with little result; pains grip like a hot claw [Hering]. Tympanitic yet tender; motion aggravates (echoing Worse motion). Mesenteric glands may feel enlarged, sensitive [Allen]. The after-act aggravation is vital: after each scanty stool the abdominal anguish persists and compels fresh straining. Warmth and gentle pressure can palliate superficially (ties to Better warmth/pressure). Compare Nux-v. (urge before and after, but less corrosive burning) and Aloe (copious jelly-like stool without the knife-like burning) [Kent], [Boger].

Keynote sphere: incessant tenesmus with scanty, shreddy, bloody mucus; pain and urging persist after stool—often worse than during the act [Hering], [Allen]. Burning and rawness at anus; haemorrhage may be bright, then dark. The rectal picture is more violent and more haemorrhagic than Merc-sol., with greater after-act torture; Canth. has burning but is dominantly vesical; Nux-v. has spasmodic urging but less corrosive mucus [Clarke], [Kent]. The rectum and bladder often “urge together,” yet Merc-cor. will show greater post-act persistence of pain. [Clinical]/[Toxicology].

Tenesmus vesicae with scalding, drop-wise emission, burning after urination; urine albuminous, smoky or blood-stained; strangury common [Boger], [Clarke]. Suprapubic pressure aggravates; warmth relieves the surface but not the inner burn (polarity). Post-dysenteric cystitis is a classic indication—rectal and vesical tenesmus together point strongly to Merc-cor. Compare Canth. (burning before, during, after; greater sexual erethism), Tereb. (smoky, coffee-ground urine, kidney focus), Sars. (pain at the close of urination) [Kent], [Boericke]. [Clinical].

Aversion to food; water itself renews pain; desires warm sips (fleeting relief) [Allen]. Coffee, alcohol, spices aggravate; milk often intolerable in acute dysentery phases [Hughes]. Metallic taste constant.

Urging in bladder with painful erections (reflex from vesical irritation) [Allen]. Prepuce and meatus sore, excoriated discharges; chancroid-like ulceration with dark, undermined edges—syphilitic colouring [Hering]. Sexual desire depressed in collapse; or irritable in early phases. Post-coital burning in urethra. [Clinical].

Excoriating leucorrhoea, acrid and burning; vulvar surfaces raw [Hering]. Menses may bring or worsen vesical/rectal tenesmus. After miscarriages or septic states—offensive discharges with burning rawness (compare Ars., Pyrog.) [Clarke]. Cystitis of pregnancy/post-partum with after-act burning suggests Merc-cor. [Clinical].

Lumbosacral aching with vesical tenesmus; sacral soreness after stool [Boger]. Dorsal weakness during chills; cannot sit upright long.

Cold, tremulous, yet burning is felt “within.” Cramps in calves during tenesmus; legs give way on returning from stool (exhaustion) [Allen]. Nails and skin around tips sore and raw (corrosive theme).

Burning, excoriating eruptions; ulcers with dark, undermined edges, sloughing base; ichorous discharge excoriates adjacent skin [Hering], [Clarke]. Erysipelatous redness may surround ulcer. Pruritus with soreness; scratching leaves a raw surface—again the caustic signature.

• Merc-sol. — Rectal and vesical tenesmus , salivation; Merc-cor. has more violent, haemorrhagic, after-act pain and earlier membrane in throat [Hering], [Clarke].
• Cantharis — Vesical burning before/during/after; sexual erethism; less rectal shreddy mucus; urine tenesmus often greater than rectal [Kent], [Boger].
• Arsenicum — Burning pains with prostration, restlessness; but Arsenicum has anxiety about death, thirst for small sips with relief more consistent; Merc-cor. has post-act tortures and salivation [Clarke], [Kent].
• Nux vomica — Tenesmus and spasms, irascibility; stools not so shreddy/bloody; pain less burning/corrosive [Kent].
• Aloe — Jelly-like stools with urgency and incontinence; less burning, more gurgling and rectal weakness [Boger].
• Kali-bich. — Tough plugs, stringy mucus, punched-out ulcers in throat; less salivation; rectal picture not of persistent burning after stool [Clarke].
• Phytolacca — Throat with glandular pains to ears, dark red fauces; less corrosive membrane and salivation [Clarke].
• Terebinthina — Haematuria, smoky urine, nephritic focus; rectal tenesmus minor vs. urinary [Boger].
• Sarsaparilla — Pain chiefly at close of urination; less albumin/haematuria; tenesmus not incessant [Kent].
• Baptisia — Septic, typhoid states with stupor; less violent tenesmus; mouth fetor present but not the corrosive burning [Clarke].
• Hepar sulph. — Suppurative, sensitive membranes; splinter-like throat pains; lacks the shreddy, bloody dysentery picture [Hering].
• Nitric acid — Syphilitic ulcerations with splinter pains and bleeding; less salivation and tenesmus coupling [Clarke].

• Complementary: Hepar-s. — both glandular, suppurative tendencies; Hepar moderates membranous processes after Merc-cor. in throat cases [Kent].
• Complementary: Nit-ac. — syphilitic and haemorrhagic tendencies; follows Merc-cor. in phagedenic ulcerations [Clarke].
• Follows well: Arsen. — in septic collapse after violent gastro-enteritis when burning persists with prostration [Kent].
• Follows well: Tereb. — after urinary haematuria subsides, to complete mucosal repair [Boger].
• Precedes well: Acon. — early vascular storm then Merc-cor. for the corrosive mucosal phase [Boericke].
• Precedes well: Bell. — high faucal congestion preceding true membrane; Merc-cor. for membranous, salivating stage [Clarke].
• Antidotes (functional): Hepar-s., China (for collapse from fluid loss), Opium (for painful spasm with retention) [Clarke], [Boericke].
• Inimical/Do not follow: Sil. after Merc. is traditionally cautioned in certain chronic mercurial states (disagreement of action) [Kent].
• Related group: Merc-sol., Merc-viv., Merc-cyan., Merc-iod. (iodide) — varying glandular/membranous emphases [Hering], [Clarke].

• Acute dysentery with incessant tenesmus and scanty, shreddy, bloody mucus is the prime indication; frequent low potencies (e.g., 3X–6X every 1–2 hours, spacing as better) are favoured by many for mucosal crises [Hering], [Allen], [Clarke].
• In post-dysenteric cystitis with recto-vesical coupling, 6C–30C can be used when generalities match (night worse, burning after urination) [Boger].
• Faucal membrane early, with salivation and burning, suggests Merc-cor. in alternation/sequence with Bell. or Hepar-s. as phases shift (avoid mechanical alternation; let the case decide) [Clarke], [Kent].
• Severe gastritis from irritants with burning and least-drink aggravation—short, frequent doses of 3X–6X may check the local storm while general totality is watched [Allen], [Hughes].
• Pearls:
  • Case: Dysentery with relentless after-stool pain; Merc-cor. 3X half-hourly for 6 doses, then hourly, checked the tenesmus overnight [Hering].
  • Case: Post-dysenteric cystitis with albuminuria; Merc-cor. 6C t.i.d. for three days eased vesical burning and frequency [Boger].
  • Case: Early membranous throat with profuse saliva; Merc-cor. 30C repeated cautiously improved deglutition within 24 hours [Clarke].

Mind

• Anxiety about anticipated pains of stool or urination. A practical pointer to the after-act torture [Hering].
• Irritability from pain; answers shortly. Pain-driven mental edge [Allen].
• Restlessness with prostration. Internal fire, external collapse [Boericke].
• Fear of swallowing. Anticipates faucal burn [Clarke].
• Delirium, muttering, septic states. Toxic phase marker [Allen].

Head

• Headache, frontal, with gastric/rectal crises. Systemic coupling [Clarke].
• Cold sweat on forehead with internal burning. Polarity sign [Boericke].
• Constriction, band-like. Vascular spasm echo [Hering].
• Vertigo on rising, faintness. Collapse tendency [Allen].
• Photophobia with nausea. Sensory irritability [Clarke].

Throat

• Membrane, early, fauces/tonsils; grey-white. Mercurial corrosive stamp [Clarke].
• Salivation profuse with dysphagia. Hallmark group sign [Hering].
• Swallowing: fluids worse (or solids), alternating. Phase variability [Allen].
• Pains shooting to ears on swallowing. Classic mercurial throat [Clarke].
• Tonsils ulcerate, edges dark. Phagedenic cast [Hering].

Stomach/Abdomen

• Gastritis, burning, least drink aggravates. Core keynote [Allen].
• Colic, cutting, hypogastric, with tenesmus. Drives to stool, no relief [Hering].
• Nausea from odours/least motion. Sensory-visceral coupling [Clarke].
• Tenderness epigastric; holds region. Protective posture [Allen].
• Warm sips temporarily relieve. Partial palliation [Hering].

Rectum

• Tenesmus, incessant, with scanty, shreddy, bloody mucus. Pathognomonic for remedy choice [Hering], [Allen].
• Pain persists after stool. The keynote of after-act agony [Hering].
• Haemorrhage with burning and rawness. Corrosive nature [Clarke].
• Urging continues though rectum empty. Spasmodic residue [Boger].
• Dysentery, offensive, fetid discharges. Septic flavour [Allen].

Urinary

• Tenesmus vesicae, burning after urination. Complement to rectal picture [Boger].
• Urine drop-wise, albuminous, bloody. Kidney involvement [Clarke].
• Strangury, suprapubic pain. Spasm sign [Allen].
• Cystitis, post-dysentery. Indication cluster [Boger].
• Pain continues after act of urination. After-act keynote [Clarke].

Skin

• Ulcers, phagedenic, dark undermined edges. Corrosive stamp [Hering].
• Discharges excoriate surrounding skin. Acridity motif [Clarke].
• Erysipelatous borders around ulcers. Inflammatory ring [Hering].
• Burning eruptions; raw after scratching. Caustic theme [Allen].
• Ichorous, offensive exudation. Septic aspect [Clarke].

Fever/Generalities

• Chill with internal burning heat. Polarity hallmark [Boericke].
• Night aggravation (pains, urging). Mercurial rhythm [Hering].
• Prostration with restlessness. Sepsis/collapse lens [Allen].
• Haemorrhagic tendency. Syphilitic tone [Clarke].
• Worse from damp and cold; better warmth (partial). Modal nuance [Boericke].

Hering — The Guiding Symptoms of Our Materia Medica (1879–91): toxicology and clinical confirmations (rectal/urinary tenesmus; throat; skin).
Allen, T. F. — Encyclopaedia of Pure Materia Medica (1874–79): toxicologic data (gastro-enteritis; kidneys; fever).
Clarke, J. H. — A Dictionary of Practical Materia Medica (1900): keynotes, modalities, differentials, relationships.
Boericke, W. — Pocket Manual of Homoeopathic Materia Medica (1901): condensed clinical indications; modalities.
Boger, C. M. — Boenninghausen’s Characteristics & Repertory (1905): modalities; recto-vesical coupling; repertory guidance.
Hughes, R. — A Manual of Pharmacodynamics (1870s eds.): pharmacology/toxicology correlations for HgCl₂.
Kent, J. T. — Lectures on Homoeopathic Materia Medica (1905): miasmatic tone; comparisons (Ars., Nux, Canth.).
Allen, H. C. — Keynotes and Characteristics (1898): salient mercurial features; night aggravation; salivation.
Dunham, C. — Lectures on Materia Medica (1879): clinical observations in acute mucosal states.
Farrington, E. A. — Clinical Materia Medica (1887): organ affinities; comparisons (Kali-bich., Phyt.).
Boger, C. M. — Synoptic Key (1915): essence; crisis prescribing pointers.
Nash, E. B. — Leaders in Homoeopathic Therapeutics (1899): dysentery/cystitis pearls; remedy relationships.