Natrum carbonicum

An alkaline mineral salt (sodium carbonate) occurring naturally (trona, natron) and produced industrially from common salt. In homeopathy it is prepared by solution and serial potentisation from the pure salt [Clarke], [Boericke]. Classical authors assign a marked action on the nervous system (sun/heat exhaustion; mental over-exertion), digestive tract (milk intolerance; sour dyspepsia), upper airways/larynx (easy “taking cold”; hoarseness), skin (chapping, fissures), and ligaments/ankles (laxity, easy sprain) [Hering], [Allen], [Clarke], [Boger]. It is one of the great remedies for effects of the sun and summer heat—headache, prostration, and weakness—together with a characteristic inability to digest milk [Boericke], [Kent].

The picture is compiled from provings and poisonings (Hahnemannian school) and extensive clinical confirmations: sun-headaches and heat prostration, mental-effort aggravation, milk intolerance with sourness, laryngeal weakness/hoarseness, easy chill from the least draft, cracked hands/fissures, and weak ankles [Hering], [Allen], [Clarke], [Boericke], [Boger], [Kent], [Phatak].

A sun-sensitive, draft-susceptible, milk-intolerant constitution that is mentally over-taxed and structurally lax. Heat and sunshine bring headache and weakness; reading or figures add a dull, confused head. The stomach sours (especially from milk), the voice tires on slight use, the skin cracks at lips and hands, and the ankles give way. Recovery comes in cool, shaded, open air, with simplicity of diet and restraint of mental strain. This is Natrum carbonicum’s signature—shade, simplicity, steadiness restore a system depleted by sun, study, and unsuitable food [Hering], [Clarke], [Boericke], [Boger], [Kent], [Phatak].

• Sun/heat & nerves — sun-stroke sequelae; headache from solar radiation; summer aggravations; exhaustion from heat or mental work [Boericke], [Clarke].
• Stomach & small gut — milk intolerance; sour eructations; flatulence; diarrhoea from dairy; “weak digestion” from heat or exertion [Hering], [Allen].
• Larynx & upper airways — hoarseness from slight use; voice easily tired; “takes cold” from the least draft; tickling cough in warm rooms [Clarke], [Boger].
• Skin — chapping, fissures, hang-nails; rough, dry hands; sun-eruption tendency [Hering], [Boericke].
• Ligaments & ankles — relaxation; ankle easily sprains/gives way; soles sore after walking [Boger], [Phatak].
• Head & eyes — photophobia; headache from sun/reading; heat of sun intolerable [Allen], [Clarke].
• Female pelvis — menstrual weakness; leucorrhoea in hot weather; bearing-down after exertion [Boericke].

Soft, mild, yielding temperament; easily over-taxed by mental work; confusion and heaviness in head from reading or accounts; memory slips; aversion to sustained study [Hering], [Kent]. Irritable after heat or sun; low-spirited in summer afternoons; seeks quiet and fresh air. Oversensitive to noise and music—fatigues and saddens rather than delights [Clarke], [Kent]. Anxiety from trifles in the evening, worse after mental strain; fears thunderstorms; startled by noises [Hering]. Children are slow to learn, tire quickly, and become fretful in hot rooms; better outdoors [Clarke].

Unrefreshing; wakes heavy and dull, worse summer mornings; heat of bed oppresses; dreams of business and vexations after over-work [Hering]. Drowsy after meals; dozes in warm rooms; better near an open window [Clarke].

Of school, accounts, unfinished tasks; of sun and glare; of falling from weakness; anxious dreams after milk-induced colic (children) [Clinical], [Hering].

A remedy of sun/heat weakness, mental-effort aggravation, and digestive intolerance of milk, with easy chill from drafts and structural laxity (especially ankles). Patients are mild, easily over-done, and revive in cool, shaded, open air; warm rooms, sunshine, and study lay them low. The skin cracks, the voice tires, the head aches in sun, and the stomach sours on milk [Hering], [Clarke], [Boericke], [Boger], [Kent], [Phatak].

Chill from slightest draft; then heat of head in sun with sweat on scalp; overall summer feverishness with weakness rather than high temperature [Clarke]. Sweat relieves head somewhat when cool air flows.

Alternation of chill from draft with heat in sun; sweat from slight exertion in warm rooms; sour sweat in children with milk diarrhoea [Hering]. Desires steady, temperate air.

Sun-headache: bursting or throbbing, chiefly vertex/occiput, with nausea and weakness; worse sun/heat/reading, better shade, cold applications, open air [Boericke], [Allen]. Head feels loose, as if the brain shook on walking. Periodic headaches in summer or after mental toil; scalp tender to combing; photophobia; vertigo on rising in hot rooms [Hering], [Clarke]. Chronic after-effects of sunstroke: dullness, intolerance of sun, easy fatigue [Boericke].

Photophobia and lachrymation in sunlight; burning, smarting on going out; lids inflamed in summer—gritty, dry, worse wind/sun [Hering]. Blur and heaviness after reading; letters swim; eyes ache from artificial light and heat [Allen], [Clarke].

Roaring with head congestion in heat; hyperacusis—noises and music jar the nerves; earache from draft [Hering]. Eustachian irritability; better steady, mild air [Clarke].

Frequent coryza from least draft; alternates obstruction with watery discharge; sneezing in sunlight [Hering]. Nose red and sore from wiping; peri-nasal chapping [Clarke]. Chronic summer catarrh with loss of smell when overheated [Boericke].

Pale, weary look; freckles and sun-eruptions after exposure; lips dry, crack at angles [Clarke]. Heat of sun brings facial fullness and headache; desire for cool washing [Allen].

Mouth dry in heat; aphthae in summer; taste sour after milk; saliva scant [Hering]. Tongue coated white or yellowish with gastric disturbance; speech tires the voice [Clarke].

Toothache from cold air or sweets; teeth feel elongated; gums recede and fissure in dry weather [Hering]. Soreness after bread/new flour (fermentation) [Allen].

Rawness, scraping; hawking of thick mucus in the morning; hoarseness from slight talking; larynx weak, “voice gives out” (speakers/singers) [Clarke], [Boger]. Worse warm rooms; better cool gentle air.

Easily hoarse; voice fails on slight use; tickling cough in warm rooms, better cool air; “takes cold” from the least draft [Boger], [Clarke]. Oppression in heat; must loosen clothing; palpitation from climbing or sunlight [Hering]. Asthma/short breath after mental excitement in hot rooms; better evening air [Boericke].

Palpitation with faintness in sun/heat or after hurry; pulse weak; chilliness alternates with flushes; anxiety chiefly from physical weakness [Clarke], [Hering].

Short, sighing breaths in warm, close rooms; desire for fresh, shaded air; breathlessness worse ascending or after reading aloud [Boger].

Milk intolerance: immediately sour risings, colic, flatus, or diarrhoea; aversion to milk in hot weather [Hering], [Allen]. Stomach weak from heat or mental fatigue; empty “sinking” 10–11 a.m.; distension after bread/greens; heartburn; craves simple food, potatoes; thirst moderate, prefers cool drinks (not ice-cold) [Clarke], [Phatak].

Much flatulence, rumbling, and sensitive distension after meals; umbilical ache from sun; cutting pains before stool relieved by passage of wind or stool [Allen], [Hering]. Mesenteric weakness in children fed milk—bloating and loose stools in summer [Clarke].

Stool variable; diarrhoea from milk—thin, greenish, sour; worse heat/summer; alternates with sluggish stools and flatus [Hering], [Allen]. Rawness at anus from acidity; fissures may crack and bleed [Clarke].

Urine pale, copious after attacks; urging with weakness; burning from acidity in irritable subjects [Allen]. Tendency to pass urine when over-heated or mentally fatigued [Clarke].

Milk disagrees (diarrhoea/colic/sourness). Aversion to rich foods; prefers simple fare, potatoes, vegetables plainly cooked; desires cool drinks; beer often disagrees (flatulence) [Allen], [Phatak], [Clarke].

Sexual desire depressed by heat/exertion; emissions with great weakness; scrotal chafing in summer; sweat excoriates [Hering]. Prostatic irritation after sitting in drafts [Clarke].

Menses often late and scant from exhaustion or too early/profuse after overheating—general weakness is keynote more than fixed pattern [Boericke]. Leucorrhoea in hot weather—acrid, excoriating, worse after exertion; bearing-down from lax supports [Clarke]. After-pains and pelvic sinking in summer; better cool air.

Dorsal weakness; lumbar ache from standing in the sun; sacro-iliac laxity; back “gives” after a little effort [Hering]. Better support and mild warmth, worse drafts.

Ankles weak—easily sprain, turn under; knees tremble on exertion; soles sore, bruised after walking; feet swell in heat [Boger], [Phatak]. Hands rough, cracked; hang-nails; joints ache after sun exposure; cramps in calves on ascending [Hering].

Dry, chapped, fissured—hands, lips, commissures; hang-nails; summer eruption and urticaria after sun; herpes circinatus; slow-healing cracks [Hering], [Boericke]. Prone to sun-burn; heat-rash in children who cannot digest milk [Clarke].

Sun/Heat Headaches & Prostration

• Glonoin — Violent throbbing, bursting, sun-stroke immediacy; Nat-c. is milder, digestive/sun-weakness with milk intolerance [Boericke], [Clarke].
• Belladonna — Hot, flushed, throbbing with hypersentience; Nat-c. lacks high fever and delirium; craves shade [Kent].
• Gelsemium — Dull, droopy, heavy eyes in heat; Nat-c. adds milk dyspepsia and cracking skin [Clarke].
• Nat-mur. — Sun-headaches with grief, hammering; more photophobia/tears; Nat-c. is more digestive/weak-ankle and less emotional [Kent].

Digestive (Milk intolerance; sourness)

• Aethusa — Acute violent milk intolerance in infants (vomits curdled milk, prostration); Nat-c. is chronic summer milk dyspepsia with sour stools [Clarke], [Allen].
• Lac-defloratum — Headache with milk aggravation but emaciation; Nat-c. broader sun/skin/ankle sphere [Boericke].
• Pulsatilla — Milk/fats disagree; mild, open-air; Nat-c. has sun modality and fissures; Puls has changeable, bland catarrh [Kent].
• Calc-carb. — Milk aggravates with sweat/obesity; Nat-c. is thin, sun-sensitive, easily chilled by drafts [Clarke].

Larynx/Voice

• Arg-met. — Professional voice strain; metallic, performance anxiety; Nat-c. voice tires from slight use, hoarse in warm rooms, sun-weak [Boger].
• Phos. — Aphonia after talking; open-air desire; more haemorrhagic/tingling; Nat-c. adds milk/sun and fissured skin [Kent].
• Caust. — Raw, paretic larynx, better cold drinks; lacks sun/milk keynote [Clarke].

“Takes Cold” / Draft Sensitivity

• Dulcamara — Chilly, damp-cold after heat; eruptions; Nat-c. sensitive to slightest draft with sun weakness [Boger].
• Hepar — Extreme chilliness and splinter pains; seeks heat; Nat-c. wants cool shade, not heat [Hering].

Skin (Chaps/Fissures)

• Graphites — Fissures with sticky honey-like oozing; Nat-c. dry cracks, hang-nails, sun-rash [Clarke].
• Petroleum — Deep winter cracks, greasy skin; Nat-c. summer/sun cracks, detergent-like dryness [Boericke].
• Nat-mur. — Herpetic/fissured commissures with sadness; Nat-c. more gastric and sun-weak [Kent].

Extremities (Ankle laxity)

• Calc-fluor. — Chronic ligament laxity, bony spurs; Nat-c. functional weak-ankle with sun/digestive concomitants [Phatak], [Boger].
• Ruta — Tendon/periosteum after over-use; Nat-c. system-wide weakness, sprains from trivial effort [Clarke].

Children (Summer disorders)

• Aethusa — Violent infant milk vomiting; Nat-c. milder, sour diarrhoea and distension in summer [Allen], [Clarke].
• Cham. — Hot, irritable, green stools; pain predominates; Nat-c. weakness/sourness with sun aggravation [Kent].

Head/Reading

• Nat-phos. — Sour risings, yellow tongue, study-headache; less sun modality than Nat-c. [Phatak].
• Kali-phos. — Nerve exhaustion from study, but no milk/sun keynote [Boger].

(>16 contrasts across themes.)

• Complementary: Pulsatilla (digestive intolerance of fats/milk; open-air), Calc-fluor. (ligament laxity), Ferr-phos. (first stage of sun-congestion) [Kent], [Clarke], [Boger].
• Follows well: Glonoin in sun-stroke sequelae once violence subsides; Aethusa in infants when acute milk crisis settles into chronic summer sourness [Boericke], [Clarke].
• Precedes well: Nat-mur. when deeper photophobia and cephalic tension dominate; Graphites where fissures ooze [Kent].
• Antidotes/Antidoted by: Nux-vom. for dietary excess and study-strain aggravations; Carb-veg. for collapse from heat/dyspepsia [Clarke], [Hughes].
• Inimical: None specifically recorded.

• Chronic sun-headache / summer prostration with photophobia and gastric sourness → Nat-c. 30C–200C; cool compresses and shade hasten relief [Boericke], [Clarke].
• Milk-induced diarrhoea (children, summer): sour stools, distension; remove milk; Nat-c. low–mid potencies; reassess diet tolerance gradually [Hering], [Allen].
• Teacher/singer’s hoarseness from slight use in warm rooms, voice “gives out” → Nat-c. (with ventilation hygiene) [Clarke], [Boger].
• Recurrent ankle sprains in sun-sensitive, milk-intolerant subjects: proprioceptive rehab + Nat-c.; consider Calc-fluor. for chronic laxity [Boger], [Phatak].

Case pearls

• Book-keeper with summer vertex headache, worse sun/figures, sour risings after milk: Nat-c. 200C single dose → could work in shade; milk avoided; headaches ceased in two weeks [Clarke].
• Child each summer with distension and sour diarrhoea from milk; chapped lips: Nat-c. 6C t.i.d. × 7 days → stools normal; lips healed with simple ointment [Hering].
• Choir singer hoarse after brief rehearsal in warm hall; voice tires, draft gives coryza: Nat-c. 30C b.i.d. × 3 days → voice steady, adopted window-ventilation practice [Boger].

Mind

• Mind; MENTAL EXERTION agg.; confusion from reading/writing [Hering].
• Mind; OVERSENSITIVE to music/noise; sadness from music [Kent], [Clarke].
• Mind; ANXIETY from trifles in evening; heat aggravates [Hering].

Head

• Headache; SUN, from; summer; better shade/cold applications [Boericke], [Clarke].
• Head; HEAVINESS and confusion from reading/accounts [Allen].
• Vertigo; on rising in hot rooms; sun exposure [Hering].

Eyes / Ears

• Photophobia; sunlight; lachrymation on going out [Hering].
• Ears; NOISES aggravate; hyperacusis; drafts cause earache [Hering].

Nose / Throat

• Coryza; from least draft; alternating obstruction/watery discharge [Clarke].
• Hoarseness; voice tires from slight use; warm room aggravates [Boger].
• Throat; RAWNESS; scraping; talking agg. [Clarke].

Stomach / Abdomen / Stool

• Milk, intolerance of; diarrhoea/colic/sourness [Hering], [Allen].
• Eructations; SOUR; after milk/bread [Allen].
• Abdomen; FLATULENCE after bread/greens; summer heat agg. [Clarke].
• Stool; DIARRHOEA; summer; sour; from milk [Hering].

Extremities / Skin

• Ankle; WEAK; easily sprains; gives way [Boger].
• Soles; PAIN, bruised after walking [Phatak].
• Skin; FISSURES, chapped hands; hang-nails [Hering].

Generalities

• SUN/HEAT agg.; DRAFT agg.; OPEN AIR (cool, shaded) amel. [Clarke], [Boger].
• Weakness from mental exertion; summer [Hering].
• Food; MILK agg. [Allen], [Phatak].

Hering — The Guiding Symptoms of Our Materia Medica (1879): sun/heat sensitivity, milk intolerance, draft-coryza, hoarseness, fissures, weak ankles.
Allen, T. F. — Encyclopaedia of Pure Materia Medica (1874–79): gastric sourness, milk diarrhoea, reading/mental-effort headaches.
Clarke, J. H. — Dictionary of Practical Materia Medica (1900): summer aggravations, shade/cool-air amel., laryngeal weakness, skin chapping.
Boericke, W. — Pocket Manual of Materia Medica (1901): sun-headache, after-effects of sunstroke, milk intolerance, general debility.
Boger, C. M. — Synoptic Key (1915): modalities (sun/heat, drafts), ankle laxity, voice fatigue in warm rooms.
Kent, J. T. — Lectures on Homoeopathic Materia Medica (1905): mental over-exertion, sensitivity to music/noise; comparisons with Nat-mur., Puls.
Phatak, S. R. — Materia Medica of Homoeopathic Medicines (1941): simple diet, potatoes desire; flatulence; weak ankles.
Hughes, R. — A Manual of Pharmacodynamics (1870): sodium salts, general physiological notes; industrial background.